review and update of the uk source of dioxins, dioxin-like...

Review and Update of the UK Source of Dioxins, Dioxin-Like Polychlorinated Biphenyls and Hexachlorobenzene for Emissions to Air, Water and Land - Annex

Report to the Department for Environment, Food and Rural Affairs

ED43184

Issue 2

July 2009

Review and Update of the UK Source Inventories: Annex AEA/ ED43184/Issue 2

ii AEA

Title Review and Update of the UK Source Inventories of Dioxins, Dioxin-Like

Polychlorinated Biphenyls and Hexachlorobenzene for Emissions to Air, Water and Land - Annex

Customer The Department for Environment, Food and Rural Affairs

Customer reference CB0404

Confidentiality, copyright and reproduction

File reference AEAT/ENV/R/2767

Reference number ED43184 - Issue 2

AEA Group

329 Harwell Didcot Oxfordshire OX11 0QJ t: 0870 190 6437 f: 0870 190 6315 AEA is a business name of AEA Technology plc AEA is certificated to ISO9001 and ISO14001 Author Name Robert Whiting Mike Wenborn and Neil Passant

Approved by Name Peter Coleman

Signature

Date

AEA/ ED43184/Issue 2 Review and Update of the UK Source Inventories: Annex

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Table of contents

1 Inventory Sector Estimates 1

1.1 Power Generation (1A1a) 2

1.2 Refinery Sector (1A1b) 8

1.3 Other Industrial Combustion (1A2f) 13

1.4 Commercial & Institutional Combustion (1A4a) 31

1.5 Residential Combustion (1A4b) 37

1.6 Minerals: Cement Production (2A1) 44

1.7 Minerals: Lime Production (2A1) 51

1.8 Other Minerals Production (2A7) (Glass, Brick, Tiles, Ceramics and Asphalt) 53

1.9 Other Chemical Manufacture (2B5) 60

1.10 Metal Processes : Iron & Steel (2C) 66

1.11 Metal Processes: Non-Ferrous Metals (2C) 72

1.12 Paper & Pulp (2D1) 78

1.13 Leakage from Electrical Equipment (2G) 78

1.14 Fragmentisers & Shredders (2G) 84

1.15 Dry Cleaning 85

1.16 Textiles (3C) 87

1.17 Manufacture of Dyes and Inks (3C) 88

1.18 Composting (4D1) 89

1.19 Pesticides (4G) 93

1.20 Landfill Waste activities (6A) 100

1.21 Waste Water and Sewage Sludge (6B) 105

1.22 Incineration (6C) 110

1.23 Incineration: Healthcare Waste (6C) 116

1.24 Incineration: Sewage Sludge (6C) 118

1.25 Incineration: Crematoria (6C) 119

1.26 Other Waste Disposal: Agricultural Burning (6D) 124

1.27 Other Waste Disposal: Natural and Accidental Fires (6D) 129

1.28 Other Waste Disposal: Other Open Burning (6D) 132


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1 Inventory Sector Estimates

This Annex covers the sector specific approaches and assumptions used to estimate releases of POPs to the environment and the results calculated, where possible for the period 1990 to 2006.

The following sectors are discussed in detail:

NFR Code Sector

1A1a Power Generation 1A1b Refining

1A2f Industrial Combustion

1A3b Road Transport

1A3c Rail Transport

1A3d National Navigation

1A3eiii Air Craft Support Vehicles

1A4a Commercial & Institutional Combustion

1A4b Residential

1A4c Agricultural Machinery and Vehicles (see transport)

2A1 Cement & Lime

2A7 Glass, Ceramics and Bricks

2B5 Other Chemical Manufacture (including Chlorine and PVC)

2C Metals: Iron & Steel, Non Ferrous Metals

2D1 Paper & Pulp

2G Transformers & Capacitors, Fragmentisers

3B Dry Cleaning

3C Textiles and Dyes

4D1 Composting

4G Pesticides

6A Landfill

6B Water Treatment & Sludge Disposal

6C Waste Incineration

6D Other Waste Disposal

z_1A3di(i) International Shipping (see transport)


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1.1 Power Generation (1A1a)

1.1.1 Sector Description (NFR code 1A1a)

The NFR category 1A1a covers fuel consumption for the purpose of power generation. This sector can be further sub-divided by the size of the combustion plant (>300 MW or <300 MW). This sector will include all combustion of fuels for the purpose of electricity generation. Therefore this sector includes all current municipal solid waste (MSW) waste to energy plant also known as incinerators and Combined heat and power plant. Where MSW is used in the form of refuse derived fuel for heat production it is dealt with in Industrial Combustion. Older MSW incinerator plant which did not generate electricity are dealt with in Waste Incineration (NFR 6C) as do other incineration processes such as hazardous waste incineration and cremation.

The fuels used for power generation have traditionally been coal, oil and gas, coal making up the greater proportion until the mid 1990s. More recently there has been a shift alternative fuel sources such as biomass. There has also been a growth in alternative power generation from ‘green’ sources, which as of 2007 made up 5% of the UK demand (with a target of 20% for 2020. BERR). It is expected that in future years this downward trend of coal use in power generation will continue as the new generation of nuclear power stations come online and the existing coal fired stations reach the end of their lifespan. This will affect the trends seen in the generation of POPs emissions.

1.1.2 Inventory Development

The emissions to air quoted within the NAEI have been based on a combination of methods. Where possible activity data has been sourced directly from the power providers, or reference sources such as DUKES (Digest of UK Energy Statistics), which use operator data. These have then been used with literature emission factors, for dioxins this will chiefly be the HMIP (1995) report and the Environment Agency report (2006). For PCBs and HCB the chief emission factor sources have been Dyke (1997) and Van der Most (1992) respectively. The use of literature emission factors to represent the entire time series will raise the level of uncertainty in the emissions, with the Van der Most figures having the highest level of uncertainty. This is because monitoring data from a given year will provide a ‘snap shot’ of emissions at the current level of process practice and abatement, and may not reflect previous or future years accurately. However as reference data is scant, this approach will likely provide the best estimates, noting the high uncertainties and caution when using the data.

A second method used within air estimates has been to take data from the pollution inventories complied by the regulators. In these cases the data provided will be as absolute emissions. The NAEI then makes use of activity data to derive emission factors from the pollution inventory in order to provide a complete set of figures, activity, emission factor, and emission. The Pollution Inventory emissions are based on a combination of monitored data (not always carried out annually) scaled by activity data for the UK. In all cases the NAEI data have been used in the current estimates.

The emission to land calculations have been based on methodology and figures taken from the BIPRO waste report (2005), which gives detailed calculations to help generate quantities of ash produce based on tonnes of fuel burnt. This method has been used as UK specific data was not obtained. As a recommendation to improve this data set it is suggested that a better understanding of ash production and use can be gathered from talking directly to the power providers or vested stakeholder groups/committees. For the purpose of the current inventory the calculations presented in BIPRO have been used with the understanding that they will represent a degree of uncertainty in the results produced.

A full table of references for activity data and emission factors to air currently used within the NAEI are quoted in table 1.1 shown on the next page.


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Table 1.1 Detailed list of all reference sources for activity data and emission factors used for emissions in 1A1a – Power Generation to air.


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Continued

Emissions to Air: Dioxins

For coal and petroleum coke combustion an emission factor of 0.031 g I-TEQ/Mt fuel burned has been taken from the NAEI. for fuel oil and waste oil combustion an emission factor of 0.052 g I-TEQ/Mt fuel burned has been taken from the NAEI. An emission factor of 0.209 g-I-TEQ/Mt fuel burned has been used for orimulsion and 0.00149 g-I-TEQ/Mt fuel for burning oil, both from the NAEI. An emission factor of 18 g-I-TEQ/Mt of fuel has been used for scrap tyres, which represents the highest emission factor quoted for dioxins.

The emissions from scrap tyres will have the highest levels of uncertainty for this sector as there was only one plant designed to use this fuel and it did not operate for long. Hence the emission estimate was uncertain. This was not a large source and as it is no longer in operation is not important for the development of the inventory.

The overall results show a downward trend in the emission of dioxins to air from power generation, dropping from 104 g-I-TEQ in 1990 to 2.31 g-I-TEQ in 2006. While the use of coal has fallen over the same period (82 Mt burnt in 1990 and 55 Mt burnt in 2006) the chief source of dioxin emissions is actually from the combustion of MSW, and this would show that the reduction has been due to improvements in abatement from waste incinerators (generating power) as oppose to change in fuel use. This is likely due to the tightening restrictions placed on waste incinerator plants over the time series.

Emissions from energy from waste plant were much reduced during the period 1994 to 1998


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Emissions to Land: Dioxins

The combustion of solid fuels such as coal and MSW is expected to generate ash, both as fly ash caught within in pollution abatement devices and bottom or furnace ash along with a number of other possible solid residues. For example flue gas desulphurisation plant at power stations are used to make a commercial quality of gypsum solid into the building trade for plasterboard. The acid gas abatement residues from UK MSW fired energy from waste plant tend to contain significant amount of unreacted alkali mixed with the fly ash and in consequence are treated as hazardous waste. While this ash is expected to carry a certain level of contamination with dioxin the destination of the solid residues is important. question surrounds what happens to the ash once generated. Due to enforcement of housekeeping issues through the permitting process which encourages good design and operation it is expected that very little emission to land from current plant will be due to accidental release or direct emission through residues. Therefore the ash generated is expected to be either sent to controlled landfill or recycled into other industries such as cement manufacture or plasterboard.

The BIPRO report (2005) offers calculations to gauge the quantities of ash generated from combustion of fuels. BIPRO quotes that 80 kg of ash will be generated per tonne of coal burnt, and that a typical dioxin content is 0.0162 µg I-TEQ/Kg of ash generated. Note, that no reference is made to quantities sent to landfill and quantities recycled into other sectors. Coal furnace bottom ash has markets as aggregate and other building materials, coal pulverised fuel ash is also used as a pozzolan in concretes and the hollow cenospheres are used in light weight concretes. A proportion of the fly ash will pass through the electrostatic precipitators and be caught in the flue gas desulphurisation equipment from where it will enter the gypsum product in small quantities and be sold in other building materials.

The Environment Agency's paper 'Solid Residues from municipal waste incinerators in England Wales ‘ quotes that approximately 28% of the MSW input is converted to ash (3% fly ash and 25% bottom ash ). In the UK between 1996 and 2000 3.09 Mt of ash were produced from the 11 municipal solid waste incinerators then in operation. The emission factors quoted within this paper give ranges based on measurements from 0.64 – 23 ng I-TEQ/kg for bottom ash and 200 – 5800 ng I-TEQ/kg for fly ash. The UNEP toolkit (2005) states that for class 3 incinerators (controlled combustion with good Air Pollution Control Systems) fly ash will have an emission factor of 200 ng I-TEQ/kg and bottom ash 7 ng I-TEQ/kg. The current estimates have adopted UNEP Class 3 as emission factors, based on the EA reported fraction of waste to ash. The EA also state that 79% is consigned to landfill and 21% recycled into other industries. Only the 79% quantity consigned to landfill has been included in this inventory. This may set a disparity between coal and MSW as the values for coal will be total releases in ash.

The results show a decline of releases from 1990 to 1999 after which emissions increase up to the present as a result of the increasing quantities of MSW incinerated and the low concentration in coal ashes which have declined in quantity produced as a result of lower amounts of coal burnt. Ash generation quantities for MSW have risen from 137 Kt of ash generated in 1990 to 953 kt of ash generated in 2006. This trend in quantities of ash from waste to energy plant is set to increase. However the air pollution control residues containing the fly ash are disposed of to hazardous waste landfill and are not released directly to the environment.

Emissions to Air: PCBs

The emission factors for PCB emission to air as elsewhere were based on the NAEI. The references underlying these emission factors are quoted in Table 1.1. In all cases the figures quoted come from the work carried out by Dyke et al in 1997. No more recent references have been found to use for this sector. The results therefore follow the ongoing activity data. 1 kg/Mt of PCB from coal was used from 1990 to 1993, dropping to 0.84 Kg/Mt thereafter as a result of both the tightened standards on particle release which led to more effective dust removal and the increased use of flue gas desulphurisation which both captures more fly ash and cools the flue gas thus potentially encouraging PCB removal. The emission factor for fuel oil is also set as 1 kg/ Mt of fuel burnt for PCB. The emission factor for waste oil is set at 3.6 kg/Mt of fuel and scrap tyres as 0.93 kg/Mt of fuel burnt. The results show a steady decline of emission from 1990 (89 Kg) to 2006 (47 kg).

While there has been a decline in the emissions quoted they are largely static for the past 5 years. The results seen reflect directly the levels of coal use within power generation and any future trend in emissions would likely follow the levels of coal consumption which is likely to reduce given the prominence given to renewable sources of energy.


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Emissions to Land: PCB As with dioxin releases to land the combustion of solid fuel such as coal will have the potential to generate ash contaminated with PCBs formed in the combustion process. There are few measurements. The current estimates have been based on Dyke’s work from 1997 which were based on coal-fired boilers. However as was noted by Dyke the same boilers were also used to fire Refuse Derived Fuel (RDF) and it is unclear whether the emissions recorded were a reflection of the RDF portion of the fuel used. For purposes of consistency and completeness the Dyke emission factors have been retained, based on a worst case scenario of emissions to landfill from contaminated ash ranging from 23 kg down to 11 kg. The uncertainty in these emissions will be high. Emissions for residue to landfill from combustion of scrap tyres have also been calculated. These too have been based on Dyke and used with the available activity data.

Emissions to Air: HCB

The emission factor used within the NAEI estimates comes from a literature source from 1992, and relates to the formation of HCB from combustion of MSW, a process that is likely to be de novo, rather than from contamination of waste. In this case the type of process and level of abatement will be key to the emissions produced. The emission factor quoted within the NAEI is unlikely to reflect the levels of abatement currently used within the UK. It should however still reflect a suitable emission factor for the earlier part of the data series. As no other more suitable emission factor has been found, the NAEI emission factor (0.5 kg/Mt of MSW burnt) has been used to provide a complete data set noting that the uncertainty is likely to be high. The emissions in this case are small and are likely to have decreased with the implementation of better abatement equipment in the mid 1990s to new plant.

Releases to Water

No emission factors exist for the release of the POPs to water. Within this sector release of contaminated water are unlikely as the processes in contact with ash and the combustion flue gases tend to be recycled or treated before discharge. Most current MSW combustion plant have dry scrubbing systems for acid gas removal and so will not release significantly to water. Coal fired power stations may generate releases from the flue gas desulphurisation plant but no data has been found on this and the release is likely to be at very low concentrations. This means that any releases to water are likely to be small, and have not been estimated.

Products

As previously stated it is common practice within the power generation sector to use some solid residues from combustion processes such as fly ash from coal fired power plant and bottom ash from waste to energy plant for other uses such as aggregate or in cement manufacture. The MSW consumed has quoted 21% of the ash generated is recycled in this way, however no data exists for other fuels such as coal. It is therefore possible that the material supplied may contain low levels of dioxins and particularly if MSW fly ash is mixed into the bottom ash as happened for a period in the 1990s. However the end use of these products is not directly the environment and it is not possible to quantify the releases to the environment via the cement sector without further research.

Potential Future Changes

As stated in the opening paragraph of this section, the power industry within the UK continues to change and move towards low carbon fuels such as biomass, wind and tidal as well as nuclear energy. The stringent abatement in place would suggest that emissions to air from this sector will continue to fall. Increasing quantities of MSW are likely to burnt to generate electricity and avoid landfill disposal and this may lead to increased quantities of dioxins being formed.

1.1.3 Results

The graph below summarises the emission to air, land and water from the power sector, and a table of emissions is also given below.


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UK POPs Emissions: 1A1a Power Generation, 1990-2006

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

160.00

180.00

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Kg

PC

B &

HC

B &

g-I

TE

Q D

ioxin

DIOXIN AIR DIOXIN LAND DIOXIN WATER PCB AIR PCB LAND HCB AIR DL PCB AIR

Table: 1A1a Power Generation POPs Emissions in the UK, 1990-2006


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1.1.4 Data Quality, Uncertainties and Recommendations for Improving the Inventory

The current study looks to review the sources; emission factors and emissions of the POPs noted to all media (air, soil and water). While the emissions of these pollutants to air is well documented and known, the emissions to soil and water are less so, particularly in the case of water. This issue is further compounded by a definitional problem which is that solid residues are often released to controlled landfill or products which are not released to the environment on a short

The UK NAEI activity and emission factors for air are largely based on DUKES and the Pollution Inventory as well as discussion with power providers. These provide a robust dataset especially for these major sources. Data for the emission factors are more uncertain than the activity statistic which is closely monitored. Some of the emission factors used are from the UNEP Toolkit or the UNECE Guidebook, and are not necessarily reflecting the timing of changes in emission abatement nor problems which are occasionally experienced with its operation at plant.

The main sources of uncertainty in this sector are the emission factors for PCB and HCB which are both at least a decade old and reflect the paucity of measurements of these pollutants in the coal fired power station and MSW incinerators.

The highest uncertainty relates to the data for emissions of all three pollutants to land. The only reliable emission factors that can be sourced for emissions of solid material come from information from Germany (BIPRO 2005) and extrapolation of data from a single UK paper based on a 5 year time frame (1992-1997) there is no means to cross reference against other UK sources of information. Within this sector the emission of dioxins to soil (almost entirely landfill – not accidental release) from the combustion of MSW carries the greatest concern for the sector, and would warrant further review.

The recommendations to improve the emission estimates for the Power Generation sector will include a review and update of the PCB and HCB emission factors against current levels of abatement in the UK. Also the incorporation of the fate of the solid residues; landfill, products, releases to environment of solid material needs to be clarified by consulting with the industry and measurements.

1.1.5 References (1A1a)

• BERR – strategy for renewable energy - http://www.berr.gov.uk/whatwedo/energy/sources/renewables/

• Digest of UK Energy Statistics (DUKES) – Published by BERR

• Dyke (1997) – A review of dioxin releases to land and water in UK.

• Dyke (1997) – Releases of PCBs to the UK environment. Report to ETSU on behalf of DETR – AEAT – 2731

• NAEI (UK) database 1990 – 2006

• The Pollution Inventory (England and Wales) (PI), Scottish Pollution Release Inventory (SPRI) and Inventory of Sources and Releases (Northern Ireland) (ISR).

• Environment Agency (2002) Solid Residues from municipal waste incinerators in England Wales.

• BIPRO (2005) Study to facilitate the implementation of certain waste related provisions of the regulation on Persistent Organic Pollutants (POPs).

1.2 Refinery Sector (1A1b)

1.2.1 Sector Description (NFR Code 1A1b)

This sector covers the fuel use based emissions from Petroleum Refineries. Refineries convert crude oils from a range of sources into a variety of products which include fuels and road surfacing products such as bitumen but also export feedstocks for chemical production and in some cases carry out synthesis on site. Currently the UK has nine major petroleum refineries (UKPIA) all of which are based at coastal or estuarine locations, reflecting the fact that crude oil historically and in the future has been imported into the UK via sea transport. Annual crude oil throughput at these facilities varies year on year, but for the past 3 years has been at or around 80 Mt (UKPIA).


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The fuel use at UK facilities is reported within the BERR publication the Digest of UK Energy Statistics (DUKE) annually.

The trend within the activity data shows the key fuels to be fuel oil and petroleum coke. While fuel oil has been a staple fuel in this industry (2.1 Mt consumed in 1990) it’s use has continued to decrease over the time series of the current inventory (1990 – 2006) dropping to 0.997 Mt in 2006. Petroleum coke has fluctuated over the time series but has seen a gradual increase from 0.976 Mt in 1990 to 1.358 Mt in 2006. This change in quantity of fuel used would suggest an improvement in energy efficiency as well as a switch in the type of fuel used.

These changes in activity will thus have knock-on effects on emissions, as well as likely effects from improving abatement.

Emission factors for the current sector have largely been taken from one reference source, based on research carried out by the Energy Institute. While this source provides valuable data from measurements taken at source, it will also represent only one ‘snap-shot’ of the time series, and therefore the levels of uncertainty will be greater for the early part of the time series examined.

Table 1.2 shows details all reference sources for activity data and emission factors to air.

Table 1.2 Reference Sources used within the inventory for 1A1b Petroleum Refinery

NFR 1A1b Petroleum Refinery Activity Emission factor

Dioxins Name Name Name

Fuel Oil Petroleum Refinery DUKES Energy Institute, UK oil refinery and the atmosphere emission of dioxins (2005)

Gas Oil Petroleum Refinery DUKES Energy Institute, UK oil refinery and the atmosphere emission of dioxins (2005)

Napthalene Petroleum Refinery DUKES Energy Institute, UK oil refinery and the atmosphere emission of dioxins (2005)

Petroleum Spirit Petroleum Refinery DUKES Energy Institute, UK oil refinery and the atmosphere emission of dioxins (2005)

Petroleum Coke Petroleum Refinery DUKES HMIP, Review of dioxin emissions in the UK (1995)

Miscellaneous fuels Petroleum Refinery DUKES Energy Institute, UK oil refinery and the atmosphere emission of dioxins (2005)

DUKES - Digest of UK Energy Statistics. HMIP – Her Majesty's Inspectorate of Pollution


The emission factors for dioxin quoted within the NAEI have been used, noting that the inventory covers a time span between 1990 – 2006. The default emission factor set for fuel oil, gas oil, petroleum spirit and miscellaneous fuels is 1 g I-TEQ/Mt fuel used. The default emission factor quoted for petroleum coke is 2.4 g I-TEQ/Mt fuel used, and comes from an older reference source. No activity


10 AEA

data or emission factors for the use of natural gas has been obtained and so cannot be covered in the current inventories. Any emissions of dioxin from natural gas usage are likely to be very small.

The results show a fluctuating but largely steady emission of dioxin to air (4.5 g I-TEQ in 1990, 4.2 g I-TEQ in 2006), this is seen against a dropping use of fuel oil, the difference made by a steadily increasing use of petroleum coke over the same time frame.


No data are available for HCB emissions from a petroleum refinery.


No data are available for PCB emissions from combustion process at petroleum refineries.

Residues / Releases to Land

The majority of the UK plants use hydro-treatment for the desulphurisation of crude oil, using hydrogen as a catalyst and forming hydrogen sulphide as the product. While this process is likely to form waste sludge, this will be treated ‘in house’, formation of POPs will relate to the chlorine content of the crude, which is likely to be negligible. This would suggest any release to land from this sector is likely to be small and disposed of to controlled landfill.

Releases to Water

Significant releases to water would only be expected if wet scrubbers were used, currently within the UK the nine major refineries use gas recovery technology as oppose to wet scrubbers (UKPIA). This would suggest that emissions to water from this sector would be low, although very little data exists on historic practices and emissions.

Products

POPs emissions from petroleum products are calculated in other sectors and so are not included here.


Unless any large new refinery plants are opened, or particularly if the types of fuel use are changed, the emissions of POPs from this sector are likely to remain low.

1.2.3 Results

The graph below summarises the emission to air, from the refinery sector, and a table of emissions is also given.


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UK POPs Emissions: 1A1b Refinery, 1990-2006

0.000

1.000

2.000

3.000

4.000

5.000

6.000

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

g-I

TE

Q D

iox

in

DIOXIN AIR

Table: 1A1b Petroleum Refineries POPs Emissions in the UK, 1990-2006

Review and Update of the UK Source Inventories: Annex

12


The main uncertainties within this sector stem from the lack of availability of current or historic emission factors. The activity data is robust and has been presented for all years of the inventory showing changes in fuel use and type over that time frame.

However the emission factors used, can only provide a guide to the likely emissions, noting that single values have been used for all years, and often the same emission factor has been used for multiple fuel types in the absence of appropriate measurements. The current emissions quoted will also not take into account changes in process technology and abatement. The petroleum refining sector is dynamic and has grown significantly within the UK over the last thirty years. Even in recent times changes in technology such as the new CHP plant installed by Conoco-Philips at their plant on the Humber in 2004 (UKPIA) will have an impact on emissions.

The dioxin emissions from this sector make a small but not insignificant portion of the total dioxin emissions to air for the UK. The uncertainty seen within the emission factors used mean that the figures quoted for this sector are only indicative. Note however that based on the available data other sectors within the current inventory will hold a higher priority for review and improvement.

The recommendation to improve the release estimates would be to monitor releases from a representative proportion of combustion sources and process at the major UK sites, noting the diversity seen within the sector and including any releases to water treatment.

References (1A1b)

• Energy Institute, UK oil refinery and the atmosphere emission of dioxins (2005)

• Digest of UK Energy Statistics (DUKES) – Published by BERR

• HMIP, Review of dioxin emissions in the UK (1995)

• UK NAEI 1990 - 2006

• ‘UK Oil Statistics’, UKPIA (UK Petroleum Industries Association) www.UKPIA.com


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1.3 Other Industrial Combustion (1A2f)

1.3.1 Sector Description (NFR Code 1A2f)

This section covers emissions of POPs from combustion in the industrial sector principally for heat either process, space or water heating and includes the emissions from specific industrial sub-sectors such as chemicals (1A2c), pulp & paper (1A2d) and food & drink (1A2e). The combustion emissions in industrial sectors relating to metals (Iron & Steel – 1A2a, Non Ferrous Metals – 1A2b) are all included within the 2C sector in these inventories. However emissions for energy-intensive industry sectors such as cement manufacture and the metal processes other than combustion are included within other sectors. The 1A2f sector mainly includes the various types of small-scale furnaces / boilers at small-scale industrial sites, including: combustion of waste wood (bark, saw dust, etc) in furnaces at wood processing sites or furniture manufacturers, combustion of fuels for heating at workshops, small factories, etc. Fuels used are mainly gas and oil but also include coal and wood (sometimes including treated wood).

Combustion of treated wood (e.g. for construction, fencing, furniture) is particularly significant for POPs. For example where wood is pre-treated with chlorinated chemicals, its combustion can be a potentially significant source of dioxin emissions to air. However, the use of these chemicals has been regulated for many years and so these sectors will only see small quantities of waste wood which has been incorrectly assessed as suitable for fuel use outside waste incineration plant.

There is likely to be limited atmospheric emission abatement technology used in small-scale combustion appliances. The larger types of solid fuel fired industrial furnaces are likely to include either cyclones or Electro-Static Precipitators (ESPs), which will lead to some residue is collected as fly ash, but most of the ash collected in small scale combustion facilities is likely to be grate ash. In addition, some waste oils are burned in small combustion plant for heating, for example in car maintenance workshops.


As this sector covers a wide range of locations and industry types the activity data is of two types: Firstly there is commercially sold fuels such as coal, coke and fuel oil. This data is reported within DUKES. In some cases further calculations are used to estimate the fuel use within particular industry sectors. The second type is the non-traded fuels which tend to wood and other biomass such as straw which are generated on site and so there are no data beyond statistical surveys. In some cases the wood burnt may be recovered waste timber either from the sites own production rejects (Sawdust, offcuts etc) . In this case estimates have been made within the NAEI to gauge the level of wood burning within industry, as with other kinds of waste burning such as those seen in category NFR 6D, it is extremely difficult to accurately gauge the quantities burnt and this will likely vary from year to year depending on relative fuel prices and other factors.

The emission factors applied to this activity data come from a range of literature reviews dating from 1992 – 2001. The research carried out by Thistlethwaite (2001) on small scale wood burning boilers partially updates Dyke’s work, although as with over parts of the inventory these are single pieces of research then applied to a wide range of years, and different processes, so the confidence of these values should be treated with care given the way that they are used.

To help contrast the emission factors selected Table 1.3 below compares the values used in the NAEI for dioxin emissions (to air) from word burning against the default values quoted within the UNEP toolkit from 2005. The figures show that the values quoted within the NAEI fall around those quoted by UNEP. While the UNEP approach focuses on the nature of the process and abatement, the NAEI figures focus on the nature of the wood treatment and likely emission. In most cases the values are close to UNEP class 2, updated furnace continuous cycle furnace with some abatement. This is the class that is typically seen as the average or middle of the range furnace. The only exception is wood treated with PCP, which is considerably higher and reflects the level of contamination by chlorine based product more likely to assist in the formation of dioxins. A full table of all activity reference data and emission factors to air are given in Table 1.4 below


14

Table 1.3 Comparison of NAEI wood burning emission factors with the UNEP toolkit.

NAEI quoted emission factors for wood combustion

UNEP (2005) quoted figures for wood and biomass incineration

Wood (treated with Creosote)

12.6 µg I-TEQ/t Older, Batch type furnace, no Air

Pollution Control

100 µg I-TEQ/t

Wood (treated with Lindane)

14 µg I-TEQ/t Updated, continuous cycle furnace with some Air Pollution

Control

10 µg I-TEQ/t

Wood (treated with PCP)

96.5 µg I-TEQ/t State of the Art system, with fully

integrated Air Pollution Control system.

1 µg I-TEQ/t

Untreated wood 12.6 µg I-TEQ/t


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Table 1.4 Reference Sources used within the inventory for 1A2f Industrial Combustion


16

Continued.


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Continued.


18

Emission to air: Dioxins

The industrial combustion sector comprises a wide variety of sources. The emission factors can be divided into some that remain constant and those where data has been obtained to allow them to vary with time. A full set of tables (1.5 and 1.6) for both types of emission factor are given below.

The emissions of dioxin to air from the sector have seen a decrease from 37.45 g I-TEQ in 1990 to 13.70 g I-TEQ in 2006. This decline is caused by changes in the fuel used in industry and improved abatement. The major changes are the decline in coal and fuel oil combustion as energy intensive manufacturing industry has closed and been replaced by the service sector. In 1990 3.9 Mt of coal and 3.78 Mt of fuel oil were consumed by ‘other industry’, by 2006 this had dropped to 1.18 Mt of coal and 0.72 Mt of fuel oil.

In 1990 the dioxin emission associated with coal and fuel oil was 13.25 g I-TEQ (37.45g I-TEQ total), in 2006 this was 3.40 g I-TEQ (13.70g I-TEQ total), illustrating the significant proportion that these two fuels have on this sector. The change is driven by changes in fuel use.

The other major contributing source has been the combustion of wood. Unlike other fuels the quantities consumed tends to fluctuate, likely due to what wood is available and market forces on other fuel types. The quantities of wood treated with chemicals relevant for dioxin formation however will have declined over the time series as their use became banned and treated wood was removed. In 2006 4.18 g I-TEQ came from industrial wood combustion, largely untreated wood. However 2006 was a year for wood use, in 2004 where greater quantities were used wood combustion accounted for 11.15 g I-TEQ more than half of the then total emission from this sector.

This would suggest that the change in fuel types has made wood combustion within industrial boilers appear more significant than formerly . While estimates of the quantity of wood burnt fluctuate, it is likely given the current emphasis on the generation of energy from renewable sources that this will increase in future. However measurements on small industrial wood boilers show widely varying results and hence there is considerable uncertainty as to whether the current emission factor will remain appropriate in the future.

Table 1.5 A table of constant emission factors used for dioxin emissions to air

Source and Activity Emission Factor Units

Other Industrial Combustion – Coal / Coke 2.4 g ITEQ/Mt of fuel burnt

Other Industrial Combustion - Fuel Oil 1 g ITEQ/Mt of fuel burnt

Other Industrial Combustion - Gas Oil 1 g ITEQ/Mt of fuel burnt

Other Industrial Combustion - Burning Oil 1 g ITEQ/Mt of fuel burnt

Other Industrial Combustion – Lubricants 4 g ITEQ/Mt of fuel burnt

Other Industrial Combustion - Pet. Coke 2.4 g ITEQ/Mt of fuel burnt

Other Industrial Combustion - Solid Smokeless Fuel 2.4 g ITEQ/Mt of fuel burnt

Other Industrial Combustion - Wood (creosote) 12.6 g ITEQ/Mt of fuel burnt

Other Industrial Combustion - Wood (Lindane) 14 g ITEQ/Mt of fuel burnt

Other Industrial Combustion - Wood (PCP) 96.5 g ITEQ/Mt of fuel burnt

Other Industrial Combustion - Wood (untreated) 12.6 g ITEQ/Mt of fuel burnt

Solid Fuel Transformation plant (SSF) - Coke combust. 2.4 g ITEQ/Mt of fuel burnt

Coal mining - Collieries Combustion 2.4 g ITEQ/Mt of fuel burnt

Agriculture - stationary combustion – Coal / Coke 2.4 g ITEQ/Mt of fuel burnt

Agriculture - stationary combustion – Fuel Oil 1.0 g ITEQ/Mt of fuel burnt

Industrial off-road mobile machinery - All Fuel Types 1 g ITEQ/Mt of fuel burnt


AEA 19

Table 1.6 A table of varying emission factors used for dioxin emissions to air

Source and Activity Emission

Factor Units Year

Solid Smokeless Fuel Production 0.379 g ITEQ/Mt of fuel burnt 1990 - 1998

Solid Smokeless Fuel Production 0.359 g ITEQ/Mt of fuel burnt 1999








Coke Production (Coke Oven Door Leakage) 0.430 g ITEQ/Mt of fuel burnt 1990

















Coal Combustion – Autogenerators 0.513 g ITEQ/Mt of fuel burnt 1990 - 1999

Coal Combustion – Autogenerators 0.519 g ITEQ/Mt of fuel burnt 2000







Emission to air: HCB

There is no information on emissions of HCB from small combustion plant. It is thought in the absence of evidence that these emissions are negligible.

Emission to air: PCBs

The emission factors for PCBs are; for coal use in all applications 1 kg/Mt, and for all wood types 0.556 kg/Mt burnt. These make up the majority of the estimated PCB releases to air in this sector. As


20

with dioxin the emission of PCB to air declines over the time frame (from 18.5 kg in 1990 to 9.8 kg in 2006) and as with dioxins this is driven by the declining use of coal and fuel oil.

For the PCB emissions the key source is the use of coal in coke manufacture, and as with other parts of the sector the quantities used in coke production have declined (from 10 Mt in 1990 down to 5.9 Mt in 2006) as a result of the continuing closure of the integrated steel works in the UK and of the ending of production at a number of independent coke works.

Releases to land

The main pathway for releases to land will be through ash resulting from the combustion of coal and wood. BIPRO (2005) quote figures for ash generation through the combustion of coal; 16 kg/t for grate ash and 84 kg/t for fly ash. Dyke (1997) provides emission factors for dioxin content of ash as a range; 0.23 – 8.7 ng I-TEQ/kg ash for fly ash and 0.02 – 13.5 ng I-TEQ for bottom/grate ash. In both cases the median value has been used (fly ash 4.47 and grate ash 6.76 ng I-TEQ).

The second Dyke paper (1997) also quotes emissions of PCB from the combustion of coal, with emission factors of 1.8 – 3.6 µg /kg of ash. As has been stated in chapter 1A1a (Power Production). These emissions were based on monitoring of a coal fired boiler which also used RDF, and it is unclear whether the emissions recorded where due to coal or residues from RDF. Emissions from this source have been calculated based on Dyke for completeness, but will have a high level of uncertainty and may well be an over estimate for small coal fired plant.

LUA (1999) gives values to calculate ash generation from wood combustion in industry, this is 3.4 kg of grate ash / tonne of wood and 3.3 kg of fly ash / tonne of wood. LUA provide ranges for dioxin content in ash based on untreated and treated wood. For untreated wood this ranges from 0.23 – 1.12 ng I-TEQ / kg ash for grate ash and 117 – 372 ng I-TEQ/kg of ash for fly ash. For treated wood the values are higher, 22.3 – 1090 ng I-TEQ/kg of ash for grate ash and 722 – 7620 ng I-TEQ/kg of ash for fly ash. In all cases the median values have been used (0.675 ng I-TEQ/kg of ash for untreated grate ash, 244 ng I-TEQ/kg of ash for untreated fly ash, 556.1 ng I-TEQ/kg of ash for grate ash from treated wood, and 4171 ng I-TEQ/kg of ash for fly ash from treated wood).

Dyke (1997) also notes the emission to ash for PCB, based on monitoring of wood burning boilers (based on 10 congeners). It is unclear from the study conducted whether this was based on virgin wood or treated wood, noting that emissions would be more likely from treated wood. Dyke used the emission factor range of 2.36 – 5.27 µg /kg of ash to calculate PCB emissions for both domestic and industrial wood use. Within the current estimates it has been assumed that the lower end of this range will apply to virgin wood combustion, and the higher end of the range to treated wood. This will give total emissions of 14.80 kg in 1990 and 5.06 kg in 2006, largely from combustion of treated wood.

The results show that the emission of dioxin as ash is roughly a quarter that of the dioxin emission to air in 1990 and a round a third in 2006, based on the land emissions being from coal and wood only. As with other sectors the figures quoted represent the total quantity of dioxin within ash, no note is made of how this ash is treated and what quantities are consigned to landfill, used in other industries or lost as residue directly to land.

Unlike other sectors such as power generation the kind of apparatus covered within the current sector burn smaller quantities and controls in place may perhaps be weaker. This would suggest that the loss of ash as residue to the environment thorough accidental incidents during waste handling would be higher. Although chiefly it would be expected that the majority would still be sent to landfill.

Releases to Water

No data are available on releases to water from small-scale industrial combustion plant, but these are likely to be low as these processes are very unlikely to have wet scrubbers and so will not generate a waste water release.

1.3.3 Results

The graph below summarises the emission to air, land and water from the other industrial combustion sector, and a table of emissions is also given above.


AEA 21

UK POPs Emissions: 1A2f Other Industry, 1990-2006

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

50.00

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Kg

PC

B &

g-I

TE

Q D

iox

in

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

20.00

g W

HO

TE

Q D

iox

in L

ike

PC

B

DIOXIN AIR DIOXIN LAND PCB AIR PCB LAND DL PCB AIR

Table: 1A2f Industrial Combustion POPs Emissions in the UK, 1990-2006


22 AEA


The activity data for industrial combustion are of variable quality, data surrounding many of the commercial fuels is of reasonable quality although the attribution to specific sectors is often not as accurate as some other sectors. However data on the quantities of wood burnt are uncertain and very little data exists on the proportion of wood burnt contaminated with active ingredients relevant for dioxin formation. The emission factors are also of generally poor quality with many being based on a single measurement from a different sector.

The greatest uncertainty lies with the emissions to soil where calculations have been used to gauge likely ash generation and then in turn likely emission factors for dioxin, which are based on a range. In some cases these ranges are large, Dyke (1997) quotes the range of dioxin emission factor for coal (as fly ash) as between 2,383 ng I-TEQ/kg and 25,146 ng I-TEQ/kg ash, a range of over 20,000 ng I-TEQ. This increases the uncertainty of the results dramatically. As a guide, assuming the quantity of ash generated within the calculations remains the same, and then applying the low and high emission factor for the ranges quoted by Dyke and LUA, the total emission of dioxin as contaminated ash in 2006 ranges from 0.34 g I-TEQ to 9.52 g I-TEQ. This means that these results for this sector are dependent on the representative of the median factor used for UK releases.

1.3.5 References (1A2f)

• Digest of UK Energy Statistics (DUKES) – Published annually by BERR

• Dyke (1997) – A review of dioxin releases to land and water in UK.


• LUA 1999 – Releases of Dioxins to Land and Water in Europe

• BIPRO (2005) Study to facilitate the implementation of certain waste related provisions of the regulation on Persistent Organic Pollutants (POPs)

• Thistlethwaite, Determination of Atmospheric Pollutant Emission Factors of a Small Industrial Wood Burning Furnace. (2001) AEA

• UK NAEI 1990 -2006

• UNEP 2005 toolkit


AEA 23

Transport (1A3)

1.3.6 Sector Description

The transport sector encompasses all modes of transportation including sea and air.

Estimates have been derived for POPs emissions from road transport sources (1A3b), rail transport (1A3c), national navigation sources (1A3d), aircraft support vehicles (1A3eiii) and agricultural machinery and vehicles (1A4cii). Estimates have also been made for International Shipping (z_1A3di(i)), which are not regarded as part of UK emissions but are provided for completeness.

No emissions have been reported in the current inventory for aviation kerosene as no emission factors have been found and the application of factors from other transport fuels was judged inappropriate given that it is different fuel typically burnt in a different design of engine. Given the complexity of the calculations surrounding road transport, the emissions for dioxins to air and all other sectors will be discussed separately before discussing all other emissions to all other routes.

Road Transport (1A3b)


The UK NAEI includes fuel use and emissions data for road transport sources broken down by vehicle sub-group, including specific estimates for dioxin emissions for the following:

� Petrol cars � Petrol LGVs � Petrol Motorcycles � Diesel cars � Diesel LGVs � Diesel HGVs � Diesel coaches / buses Each of these vehicle types exhibits different dioxin emissions per unit fuel consumption, and within the UK NAEI these factors change across the time-series to take account of the changing age, composition and fuel use of the UK vehicle fleet.


The emissions of dioxins to air for road transport are derived from distance based emission factors (pg I-TEQ/km) for different sub-sets of transport type (car, LGV, HGV etc) and engine operating conditions (rural, urban and motorway driving). For cars this is further sub-divided first by fuel type (petrol : diesel ratio is based on fuel sales) and then by the presence of catalytic converter. The vehicle km data is based on surveys carried out amongst a model set of population and then multiplied to meet national population levels.

The emission factors in use are based on literature sources from the early 1990s. Measurements at this time indicated that the ethylene dichloride added to leaded petrol to scavenge the lead from the engine led to dioxin emissions. Over the 1990s the levels of lead and hence of lead scavengers decreased to zero by the end of the decade. Some fuel compositions used mixed both trichloroethylene and dibromoethylene which led to the formation of mixed bromo-chloro dioxins as well as chlorinated and brominated dioxins. However there is limited data on these compounds and the measures that controlled the chlorinated compounds also controlled them


24 AEA

The 1990 emissions for dioxin were calculated to be 29.7 g I-TEQ, however the elimination of leaded petrol and implementation of catalysts led to a significant decline. The 2006 emissions for dioxin were calculated to be 2.64 g I-TEQ.

Other forms of Transport (1A3c, 1A3d, 1A3eiii,

1A4cii and z_1A3di(i)) - Dioxins


The activity data quoted within the NAEI for the remaining parts of the transport sector is taken from both DUKES, principally for shipping, and estimates based on literature. Table 1.7 shown below gives details of the references used for activity and emissions to air.


Typically road transport makes up the largest source of dioxins within transport, coastal navigation making the next largest source (road transport for 2006 was 2.64 g-I-TEQ, coastal shipping was 2.17 g I-TEQ for the same year). While these emissions are smaller, except for International Shipping, which fluctuates with trade levels, the emissions increase over the time series. There is considerable uncertainty in the emission factors as few measurements have been made. It should be noted (bar coastal shipping), all other transport activities remain in small proportions within the transport sector and ‘other transport’ makes up a small proportion within the inventory generally.

Emission factors to air: HCBs

Emission factors for HCB were only found for shipping. The UNECE Guidebook quotes an emission factor of 0.2 kg/Mt fuel burned for sea-going vessels where the main fuel is fuel oil. It is noted that for sea bound vessels often use poor quality fuels and this may be reflected in the UNECE emission factor.

Emission factors to air: PCBs

No emission factors have been found for PCB within the transport sector and it is assumed that there are no significant emissions from these sources.


The main emissions for road, rail and sea are to air. In the case of road and rail the combustion of fuels will also generate particulate that may be contaminated with dioxins. While these materials will ultimately end up on land the initial emission is to air and as such they are counted as an airborne emission. Emissions of dioxin to land have not been calculated for this sector.


AEA 25

Table 1.7 Reference Sources used within the inventory for 1A2f Industrial Combustion

Other Transport Activity Emission factor

Dioxins Activity Code Source Name

Gas Oil 1A3c - Rail Regional

Fuel Consumption Estimates from ATOC

Assume the same as Petroleum Refinery Combustion

Gas Oil 1A3c - Rail Intercity

Fuel Consumption Estimates from ATOC


Gas Oil 1A3c - Rail Freight

NAEI Estimate based on tonne km data.


Fuel Oil 1A3d - Coastal Shipping

DUKES HMIP, A Review of Dioxin Emissions in the UK, Report No HMIP/CPR2/41/1/38, October 1995.

Gas Oil 1A3eiii - Aircraft Support Vehicles

Off-Road activity estimates made by NAEI


Gas Oil 1A4cii - Agricultural Machinery and Vehicles



Petrol 1A4cii - Agricultural Machinery and Vehicles



Fuel Oil z_1A3di(i) International Shipping

DUKES Assume the same as Petroleum Refinery Combustion

Gas Oil z_1A3di(i) International Shipping


Releases to Water

The main POPs emissions from the transport sector will be to air. While shipping may occasionally lead to accidental fuel spills the quantities lost are unknown as is the contamination in the fuel but the amount is likely to be small and so has not been calculated.


It should be anticipated that ongoing improvements in vehicle design and required fuel efficiency of the vehicle fleet will continue to lead to reductions in POPs emissions from the road transport sector in particular.

1.3.9 Results

The graphs below summarises the POPs emission to air from the road transport, rail and national navigation sectors, as well as a overall graph from all transport sectors.


26 AEA

UK POPs Emissions: Transport (1A3b Road Transport), (1A3c Rail), (1A3d Sea), 1990-2006

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Kg

HC

B &

g-I

TE

Q D

iox

in

DIOXIN AIR (1A3b) DIOXIN AIR (1A3c) DIOXIN AIR (1A3d) HCB AIR (1A3d)


AEA 27

UK POPs Emissions: Transport All Types (1A3b Road Transport), (1A3c Rail), (1A3d Sea),

(1A3eii Air Craft Support vehicles), (1A4cii Agriculutral Machinery), (z_1A3di(i) International

Shipping) 1990-2006

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

g-I

TE

Q D

iox

in

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

Kg

HC

B

DIOXIN AIR (1A3b) DIOXIN AIR (1A3c) DIOXIN AIR (1A3d) DIOXIN AIR (1A3eii)

DIOXIN AIR (1A4cii) DIOXIN AIR (z_1A3di(i) HCB AIR (1A3d)


28


As a result of the number of variables involved, and that the approach has been developed for supporting the assessment of transport emissions for all pollutants, the calculations used to quantify dioxin emissions to air from road transport are complex. Few authors outside of the Emission Inventory community have published similar calculations, particularly with regard to dioxin emission factors for different vehicle types, technologies, fuels and driving conditions. The current system employed by the NAEI to estimate these emissions is probably accurate for many of the elements but the underlying emission measurements are few in number and very dated so that despite the sophistication of the treatment of the emissions the uncertainties remain high. It may be possible to update the current emission factors with data from COPERT IV, a traffic emissions software programme and database of emission factors produced by the European Environment Agency, although this may not be sensible as for example COPERT does not provide details of emission factors for the split between leaded and unleaded petrol which is disappointing.

The uncertainty within other areas of transport have uncertainties with respect to both activity levels and emission factors. Although DUKES publishes statistics on shipping fuel consumption, there is considerable concern about the split between coastal and international shipping. This issue is currently being reviewed by the NAEI and DECC in light of a recent study on shipping emissions by Entec based on a bottom-up calculation method using detailed shipping movement data.

Activity data for rail, and off-road machinery also depend on methods of estimations because of lack of reliable national statistics on fuel consumption by these sectors. The emission factors for fuel oil and gas oil (which affects both rail and sea transport) are assumed to be the same as emission factors for the petroleum refinery sector. These are based on the Energy Institute’s report ‘UK oil refinery and the atmosphere emission of dioxins (2005)’. The application to sectors other than that they were derived for increases the uncertainty of the estimates. However emissions from ‘other transport’ sectors are small within the inventory and other sectors will retain a higher priority.

No releases have been calculated for release to land and water in the absence of data.

1.3.11 References

• European Environment Agency (2006) COPERT IV – (Computer programme to calculate road emissions from transport).

• Digest of UK Energy Statistics (DUKES) – Published by BERR annually

• Energy Institute (2005), UK oil refinery and the atmosphere emission of dioxins

• UNECE Guidebook (2006)


AEA 29

Table: 1A3b Road Transport POPs Emissions in the UK, 1990-2006

Table: 1A3c Rail Transport POPs Emissions in the UK, 1990-2006

Table: 1A3d National Navigation POPs Emissions in the UK, 1990-2006

Table: 1A3eii Aircraft Support Vehicles, 1A4cii Agricultural Machinery and Vehicles, and z_1A3di(i) International Shipping POPs Emissions in the UK, 1990-2006

Table: Dioxin emissions from transport as g WHO TEQ in the UK, 1990-2006


AEA 31

1.4 Commercial & Institutional Combustion (1A4a)

1.4.1 Sector Description (NFR Code 1A4a)

This section covers emissions of POPs from small-scale combustion in the Commercial and Institutional sector, including the use of fuels for space and water heating of offices, commercial properties, and institutions such as hospitals, universities, leisure centres and public buildings.


As with the Industrial Combustion sector (1A2f) much of the activity data for this sector comes from DUKES and represents the use of small scale appliances for heating and hot water in public buildings, offices and retail.

It should be noted that the municipal solid waste combustion activity data from DUKES has remained unchanged at 0.149 Mt per annum between 2002 – 2006. Which suggests a lack of revision of the activity statistic. It is a little surprising there is any MSW combustion in this sector given the regulatory needs on abatement. As the releases form MSW combustion dominate this sector this suggests the totals are extremely uncertain

The emission factors used within the NAEI and quoted also within the current inventory are based on literature values from 1995 (published by the HMIP) for dioxins, and Dyke’s work (1997) for PCBs.

Emission to air: Dioxins The principal emissions of dioxins to air from this sector come from the combustion of MSW. The emission factor derived for MSW in the early part of the time series is quoted as 207.50 g I-TEQ/Mt of MSW. Table 1.9 shown below states emission factors for MSW and are derived from pollution inventory data. This shows a significant drop in the emission factor from 1998 onwards while the activity data has also declined from 0.217 Mt in 1990 to 0.149 Mt in 2006. This reflects improvements made in abatement technology.

Emission factors to air: HCBs

Emission factors for HCB are only available for MSW combustion within this sector. In the absence of measurements the same emission factor (0.5 kg/Mt) has been applied to all years, resulting in HCB emissions ranging from 0.1 kg in 1990 to 0.07 kg in 2006. HCB emissions from this sector are a small proportion of the total inventory.

Emission factors to air: PCBs

PCB emissions for this sector are mainly from coal and MSW. In 1990 the PCB emission was calculated to be 2.1 kg of which 870g comes from MSW and the remainder from coal. In both cases the quantities of fuels used decline which leads to a decline in PCB emissions. In 2006 the PCB emission was calculated to be 265g, of which 116g comes from MSW and the remainder from coal.


The main release for this sector is the disposal of ash. This will include both grate ash and fly ash. No calculations are made for the final destination of this ash although it is likely that the majority will be consigned to landfill with very little lost directly to the environment through accidental release.

BIPRO (2005) quotes values for the generation of ash from coal combustion of 16 kg of grate ash and 84 kg of fly ash per tonne of coal . Dyke (1997) provides emission factors for the dioxin and PCB content of such ash (dioxin content of 4.47 ng I-TEQ/kg of fly ash and 6.76 ng I-TEQ/kg of grate ash, and PCB content of 1.8 – 3.6 µg /kg for all ash types. Releases to land decrease as a result of the reduced quantities of coal and MSW burnt : For dioxins from 0.577 in 1990 to 0.072 g I-TEQ in 2006 for PCB from 0.4 kg to 0.05 kg over the time period. It would be expect that this trend would continue as the use of coal continues to decline.


32 AEA

Table 1.8 Reference Sources used within the inventory for 1A4a Commercial and Institutional Combustion

Commercial and Institutional

Combustion 1A4a Activity Emission factor


Coal Public Sector fuel use

Extrapolation based on DUKES

HMIP, A Review of Dioxin Emissions in the UK, Report No HMIP/CPR2/41/1/38, October 1995

Coke Public Sector fuel use

DUKES HMIP, A Review of Dioxin Emissions in the UK, Report No HMIP/CPR2/41/1/38, October 1995

Fuel Oil Railways - stationary combustion


Coal Miscellaneous Fuel use



MSW Miscellaneous Fuel use

DUKES Derived from data in the PI and SPRI

HCB Name Name Name


DUKES van der Most, P. F. J. & Veldt, C., Emission Factors Manual PARCOM-ATMOS, Emission Factors for Air Pollutants, TNO report No 92-235, December 1992

PCBs Name Name Name

Coal Public Sector fuel use


AEA Estimates based on Dyke 1997.

Fuel Oil Railways - stationary combustion

DUKES AEA Estimates based on Dyke 1997.

Coal Miscellaneous Fuel use





DUKES - Digest of UK Energy Statistics. HMIP - Her Majesty's Inspectorate of Pollution PI - Pollution Inventory. SPRI - Scottish Pollution Release Inventory.

Releases to Water

Releases of dioxin to water would only be expected where wet scrubbers were used. It is expected that this is not the case for this sector and therefore no emissions are expected to water from Commercial and Institutional combustion.


It should be anticipated that the decline in coal use within this sector would continue to see a decline in both dioxins and PCBs. Greater uncertainty exists surrounding the use of MSW, but it would be expected that this practice would continue to consume small quantities of MSW.


AEA 33

Table 1.9 Full details of dioxin emission factors used for MSW in Commercial and Institutional Combustion.

Year Emission Factor (g ITEQ/Mt of fuel burnt)

1990 - 1992 207.50

1993 151.52

1994 84.71

1995 105.55

1996 18.73

1997 13.75

1998 0.96

1999 0.43

2000 0.45

2001 0.29

2002 0.28

2003 0.14

2004 0.11

2005 0.40

2006 0.15

1.4.3 Results

The graphs below summarises the POPs emission from the Commercial and Institutional Combustion sector.


The scale of fuel use in the Commercial and Institutional Combustion sector is smaller than both Industrial combustion 1A2f (17 Mt of coal consumed in 1990) and Residential Combustion 1A4b (3 Mt of coal consumed in 1990) with 1.2 Mt of coal consumed in 1990. However the dioxin emissions for this sector remain significant in the early part of the time series, and are dominated by the combustion of MSW. In 1990 the dioxin emissions to air for the Commercial and Institutional Combustion sector were 48.4 g I-TEQ (Industrial was 37.45 g I-TEQ and Residential was 17.85 g I-TEQ) and which 45.08 g I-TEQ came from the combustion of MSW.

It is recommended that the MSW activity data be investigated and the combustion facilities level of abatement be identified.

1.4.5 References

• DUKES (Digest of UK Energy Statistics 1990 – 2006)


• HMIP, A Review of Dioxin Emissions in the UK, Report No HMIP/CPR2/41/1/38, October 1995


• UK NAEI 1990 – 2006


AEA 35

UK POPs Emissions: 1A4a Commercial, 1990-2006

0.000

10.000

20.000

30.000

40.000

50.000

60.000

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Kg

HC

B &

g-I

TE

Q D

ioxin

0.000

0.500

1.000

1.500

2.000

2.500

Kg

PC

B a

nd

g W

HO

TE

Q

Dio

xin

Lik

e P

CB

DIOXIN AIR DIOXIN LAND HCB AIR PCB AIR DL PCB AIR PCB LAND

Table: 1A4a Commercial & Institutional Combustion POPs Emissions in the UK, 1990-2006


AEA 37

1.5 Residential Combustion (1A4b)

1.5.1 Sector Description (NFR Code 1A4b)

This sector includes residential combustion from household open fireplaces, stoves and boilers. Domestic bonfires are reported within sector 6D. This sector also includes garden machinery where diesel and petrol are consumed as fuels.

While the principal fuel in the UK for domestic heating is gas, with oil and liquefied gas used away from the natural gas grid, a range of solid fuels are also burnt in domestic fireplaces, stoves and boilers including bituminous coal, smokeless fuels, coke and wood. Releases of POPs will increase if certain types of domestic waste are burned on domestic fires.

In addition to the potential for emissions of POPs to air, grate ash will be generated, as well as soot from periodic chimney sweeping.


Activity data on fuels burned in residential appliances quoted within the NAEI come almost entirely from DUKES, which is updated on an annual basis. The quantities of solid fuels burned have decreased since 1990, with the exception of wood, which has increased slightly from 1990 levels (0.729 Mt of wood burnt within the UK in 1990, up to 0.854 Mt in 2006). No disaggregation is quoted for untreated and treated wood, however it is expected that waste/treated wood is more likely to be burned on bonfires, which are accounted for in sector 6D.

A full table of references for activity data and emission factors for releases to air within the NAEI are quoted in Table 1.10.


There are numerous sources of data available on emission factors for dioxins from domestic combustion. In some literature sources, factors are presented for different designs of stoves and fireplaces, and these sources demonstrate a significant range of potential factors for different types of combustion appliance. There are also considerations to be taken into account regarding the quality of the fuel noting that the chlorine content of coal can vary, and the possibility of both untreated and treated wood being used in the home. There are no statistics on the proportion of waste wood burnt domestically nor of the quantity of waste burnt.

The activity data reported by DUKES and quoted within the NAEI provides data as total fuel used; no information is available on the type of appliance the coal or wood is burnt in.

Enviros (2006) quote a wide range of emission factors for dioxin emissions from domestic coal and wood combustion as shown in Tables 1.11 and 1.12. The dioxin emission factor for coal combustion used within the current inventory and quoted within the NAEI is 2.9 µg I-TEQ/t of coal burnt. This emission factor is based on measurements of emissions from a domestic open fire burning wood and bituminous coal (Perry, 2002). While this factor is considered low compared to the UNEP toolkit and appears on the lower part of the Enviros range, it is still considered to be the most suitable given that it is based on laboratory testing rather than estimation. Recent work has suggested that dioxin formation occurs principally in the chimney and that a laboratory test such as Perry’s work will not reproduce typical chimney conditions.


38 AEA

Table 1.10 Reference Sources used within the inventory for 1A4b Residential Combustion

Residential Combustion 1A4b Activity Emission factor


Anthracite Residential Combustion



Coal Residential Combustion


Perry, R.E., Report on a project to measure emissions and calculate emission factors for a range of pollutants released to air during the combustion of solid fuels on an open fire, CPL Ltd, Report Reference 02/AEAT/1, January 2002

Coke Residential Combustion


Petroleum Coke Residential Combustion

AEA estimates based on DUKES


Solid Smokeless Fuel

Residential Combustion


Wood Residential Combustion

DUKES Enviros, Emissions of dioxins and dioxin-like polychlorinated biphenyls from domestic sources, DE0110099A, May 2006; Perry, R.E., Report on a project to measure emissions and calculate emission factors for a range of pollutants released to air during the combustion of wood.

Petrol Garden Machinery

AEA Estimate Based on Road Transport Calculations


Diesel Garden Machinery

AEA Estimate Based on Road Transport Calculations


PCBs Name Name Name

Anthracite Residential Combustion



Coal Residential Combustion



Coke Residential Combustion


Solid Smokeless Fuel

Residential Combustion


Wood Residential Combustion


DUKES - Digest of UK Energy Statistics. HMIP - Her Majesty's Inspectorate of Pollution


AEA 39

Table 1.11 Example of dioxin emission factors for coal combustion in domestic settings

Emission Factor Reference Source type

Low value High Value

Eduljee and Dyke 1996

Residential combustion

6 µg I-TEQ/t of coal 9 µg I-TEQ/t of coal

Lee at al 2005 Fireplace 3 µg I-TEQ/t coal

CRE measurements 1995

Residential combustion

5.7 µg I-TEQ/t coal

US EPA 1992 Domestic Furnaces

100 µg I-TEQ/t of coal

Enviros 2006 Residential combustion

1.5 µg I-TEQ/t of coal 100 µg I-TEQ/t coal

UNEP toolkit 2005 Domestic heating 3.59 µg I-TEQ/t*

(coal) 538 µg I-TEQ/t* (high chlorine coal)

NAEI values (based on Perry 2002)

Fireplace 2.9 µg I-TEQ/t of coal

*Conversion factor assumes coal has a value of 27842 MJ per tonne of coal.


40 AEA

Table 1.12 Example of dioxin emission factors for wood combustion in domestic settings

Emission Factor ( µg I-TEQ/t ) Reference Source type

Low value High Value

Bremmer 1994 Stoves 0.8 (wood) 1.3 (wood)

Broker 1992 Stoves 0.5 (wood) 0.9 (wood)

Bremmer 1994 Fireplace 13 (wood) 29 (wood)

Broker 1992 Fireplace 0.2 (wood) 1.1(wood)

Tame 2003 Fireplace 0.05 (wood -

untreated) 78 (wood -

contaminated)

Enviros 2006 Domestic wood

combustion (untreated)

0.043 (wood) 11(wood)

Enviros 2006 Domestic wood

combustion (contaminated)

11 µg (wood) 400 (wood)

UNEP toolkit 2005 Cooking and

Heating 20 (untreated wood)

300 (waste/contaminated

wood)

NAEI values (based on Perry 2002)

Fireplace 2.4 µg I-TEQ/t of wood

*Conversion factor assumes wood has a value of 5000 MJ per tonne of wood

As with coal the emission factor for dioxin emissions from wood in the NAEI is based on the same piece of work carried out by Perry in 2002. This states the emission factor for untreated wood to be 2.4 µg I-TEQ/ t of wood burnt. The emission factor values for wood combustion in domestic settings vary more greatly than those seen for coal. This is due to get variability in the fuel source. The UNEP toolkit update for 2007 now quotes emission factors for both ‘pellets’ as well as wood reflecting that the nature of the combustion affects the emissions.

The dioxin emissions to air for this sector have seen a steady decline since 1990, with emissions falling from 37.45 g I-TEQ in 1990 to 13.70 g I-TEQ in 2006. This decline mirrors the decline in the use of solid fuels domestically. The design and level of abatement used on fireplaces and stoves has not changed during the time series under review, particularly in the case of coal burning stoves and fireplaces. However in future wood burning appliances coming onto the market are significantly more efficient combustors and may require reduced emission factors in future.

Emission factors to air: HCB

There is no information available on emissions of HCB from domestic combustion.

Emission factors to air: PCBs The emission factors quoted for this sector are based on Dyke’s work from 1997. Very little recent work has addressed emission factors for PCBs. However these emissions are likely to be subject to similar problems as those seen with the dioxins, with highly aggregated activity data matched against appliance specific emission factors. The emission factors for bituminous coal, anthracite, coke and solid smokeless fuel are all 3.6 kg/Mt of fuel burnt. The emission factor for all wood types is 1.99 kg/Mt burnt. The results show a declining trend, from the decreasing quantities of coal burnt within this sector. Wood use within the sector is likely to be become an increasingly important source.


AEA 41

Releases to land

The main pathway for releases to land from domestic combustion would be through POP concentrations in both grate ash and soot from combustion of solid fuels (i.e. coal, and wood). It is likely that most grate ash will be consigned to landfill, although perhaps less so than other sectors given the use of wood ash in gardening. Soot will be collected during periodic chimney cleaning and normally the sweep will disposed of it. The majority of the soot would be expected to be consigned to landfill, although the risk of accidental release is greater here than other sectors.

While emission factors exist for soot (Lavric et al) activity data for soot generation is far less available, and likely to be variable depending on the combustion efficiency of the stove. The current inventory has presented emissions for grate ash only. Dyke (1997) quotes emission factors for ash generation based on tonnes of coal burnt, the figure quoted being 20.5 ng I-TEQ/t of coal (assume this is soot and grate). The UNEP toolkit quotes dioxin concentrate of ash from coal in stoves as 5000 ng I-TEQ/t of coal, which was reviewed in 2007 and updated to significantly reduce this figure to 5 – 15 ng I-TEQ/kg of ash. The Dyke figured has been adopted for the current work.

The BIPRO report (2005) quotes figures for ash generation (17 kg ash per tonne of wood) and dioxin content of wood (0.11 ng I-TEQ/kg ash). The equivalent figure quoted within the UNEP toolkit for dioxin contamination of wood ash is 0.10 ng I-TEQ/kg ash. As the UNEP toolkit is based on default values the BIPRO figure has been accepted in this case. As with the activity data and emissions to air associated with wood these emissions also remain largely static across the time frame varying little (1990 emission 1.46 g I-TEQ, and 2006 emission 1.61 g I-TEQ). No estimate is made for the split between landfill and accidental release as residue.

Dyke (1997) quotes emissions for PCB in ash generated from coal (1.8 – 3.6 µg /kg ash) and wood (2.36 - 5.27 µg /kg ash (based on 10 congeners)), as with other coal combustion sectors the emission of PCB in coal ash is based on one set of monitoring data where uncertainty existed due to possible contamination with RDF. Ash generation has been based on the figures used by BIPRO (2005) for commercial and industrial combustion of coal where 80 kg of ash are generated per tonne of coal burnt. The current estimates have assumed that the emission factors and ash generation quoted will be the same for other solid fuel types (anthracite, pet coke and coke). This stated total emissions for solid fuels (including wood) are low ranging from 1.5 kg (1990) – 0.2 kg (2006). Emissions for ash generated from wood, also based on Dyke have assumed all wood burnt will be untreated and an emission factor of 2.36 µg /kg of ash has been used.

Releases to Water

Releases of POPs to water from residential plant are likely to be negligible.

1.5.3 Results

The graph below summarises the emission to air, land and water from the domestic combustion sector, and a table of emissions is also given.


42 AEA

UK POPs Emissions: 1A4b Residential, 1990-2006

0.00

5.00

10.00

15.00

20.00

25.00

30.00

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Kg

PC

B, g

-IT

EQ

Dio

xin

, a

nd

g W

HO

TE

Q D

iox

in L

ike

PC

B

DIOXIN AIR DIOXIN LAND PCB AIR DL PCB AIR PCB LAND

Table: 1A4b Residential Combustion POPs Emissions in the UK, 1990-2006


AEA 43


There are a relatively large number of measurements of emission factors for dioxins and PCBs for the domestic sector which are highly variable. The activity data is readily available at a highly aggregated level. This means that currently within the NAEI emission factors taken from research conducted on open fireplaces has been scaled across the entire sector and all applications.

The emissions to land have a large uncertainty as to the fate of the solid residues. Disposal of ash from treated timber to gardens should be advised against given the possible dioxin and heavy metal content depending on the wood treatment chemicals used. The PCB content of ash has not been studied in the same detail as dioxins and so the estimate is uncertain. The majority of ash generated will still likely be consigned to landfill.

The emissions of dioxins and PCBs within this sector have declined over the time series (Dioxin emissions in 1990 – 17.85 g I-TEQ, and in 2006 4.41 g I-TEQ, PCB emissions in 1990 – 22.21 Kg and 2006 4.71 kg) as the use of coal has been replaced by other fuels. The use of wood however has increased over the time series and will increase in future years.

It is recommended that the appliance population be categorised and appropriate emission factors and activity statistics obtained especially for wood combustion where modern appliances will operate very differently to traditional open fires and cast iron stoves.

1.5.5 References

• Bremmer, HJ et al. (1994) “Emissions of dioxins in The Netherlands. National Institute of Public Health and Environmental Protection (RIVM) and Netherlands Organization for Applied Scientific Research (TNO). Report No. 770501018

• Bröker et al., 1992 (quoted in the Enviros 2006 Report)

• Broomfield M. (2006) “Emissions of dioxins and dioxin-like PCBs from domestic sources”, published by Enviros for DEFRA

• CRE measurements (1995) “measurements taken for domestic combustion appliances by the Coal Research Establishment (CRE), quoted in the Enviros 2006 report.


• Eduljee, GH; Dyke, P. (1996) An updated inventory of potential PCDD and PCDF emission sources in the UK. The Science of the Total Environment 177:303-321

• Lavric, ED, Konnov, AA, De Ruyck, J (2004) “Dioxin Levels in Wood Combustion-A Review,”

• Biomass & Bioenergy vol 26, no 2, p115(31)

• Lee R et al (2005) “Emission factors and importance of PCDD/F, PCB, PCNs, PAH and PM10 from domestic burning of coal and wood in the UK”, Environmental Scientific Technology Vol 39, pp 1436 – 1447

• Perry, R.E., Report on a project to measure emissions and calculate emission factors for a range of pollutants released to air during the combustion of solid fuels on an open fire, CPL Ltd, Report Reference 02/AEAT/1, January 2002

• Study to facilitate the implementation of certain waste related provisions of the regulation on Persistent Organic Pollutants (POPs) (2005) BIPRO.

• Tame, NW et al (2003), “Assessing influence of experimental parameters on formation of PCDD/F from ash derived from fires of CCA treated wood,” Environmental Science and Technology, 37 4148-4156

• UK NAEI 1990 –2006

• UNEP Toolkit (2005) Standardized Toolkit for Identification and Quantification of Dioxin and Furan Releases.

• US EPA (1992) “Compilation of emissions data: volume 1 Stationary Sources, reference AP42


44 AEA

1.6 Minerals: Cement Production (2A1)

1.6.1 Sector Description (NFR Code 2A1)

The cement production process involves the high-temperature calcination of limestone and clay in a kiln to produce clinker. Gypsum is then blended to produce cement. The high temperatures (up to 1500

oC) and long residence times required to produce the finished product means the kilns in use

work above the specifications required for hazardous waste incinerators, and mean that there is a potential for cement kilns to use a variety of fuels, in particular waste chemicals and solvents (as a means of keeping costs down), which have raised the profile of the cement sector.

The UK has fourteen large scale cement plants manufacturing around 12 Mt of cement per annum (BCA), utilising scrap tyres and waste oils as well as more traditional petroleum coke and coal However the high temperatures used and stringent abatement in place means the emissions from these sources will in general be low.

One further aspect of the cement industry is the use of fillers in the manufacture of concrete; this practice uses solid material such as ash to help bulk out the material used and in some cases help maintain stability of the product, this also helps reduce overhead costs. It is likely that ash generated within the power industry amongst others will supply such ash, and there may be an issue surrounding dioxin concentrations of such goods. The current inventory focuses on the manufacture of cement only; no calculations have been made for pre-cast concrete or quantities of ash used.


The emissions of POPs from the cement manufacture sector will reflect the fuels used and the raw materials used, both of which fluctuate from year to year.

The dioxin emissions to air have been based on data from the pollution inventories which give operator provided estimates of the annual emissions. This has been used in combination with clinker manufacture figures from the BCA (British Cement Association) to derive emission factors and provide values for activity, emission factor and emission. The Pollution Inventory data is sourced annually from the operators and should provide a relatively robust source of values, noting that uncertainty for dioxin emissions will likely be high.

The PCB emissions to air have been based on waste fuel activity data again supplied by the BCA in combination with the emission factors quoted by Dyke in 1997. As the activity data comes directly from the operators and is updated annually it will have a high level of certainty in the absence of monitoring at production sites. The emission factors quoted by Dyke relate specifically to the waste fuel used, and should help track trends in different fuel types. More recent emission factors exist such as those quoted by the UNECE guidebook, but often the activity data used is tonnes of clinker manufactured, meaning that Dyke’s values may be more relevant.

A full table of all the reference sources used for activity data and emission factors to air are given in Table 1.13.


AEA 45

Table 1.13 Reference Sources used within the inventory for 2A1 Cement and Lime Manufacture

Cement and Lime 2A1

Activity Emission factor


Process Emissions Clinker Manufacture Data supplied from the British Cement Association

Derived from emissions data reported in the Pollution Inventory, SPRI and NI ISR (Environment Agency, SEPA, NI DoE 2006)

Coal Lime Manufacture - Fuel Use

AEA estimates Derived from emissions reported in the Pollution Inventory (Environment Agency, 2004)

Coke Lime Manufacture - Fuel Use

AEA estimates HMIP, A Review of Dioxin Emissions in the UK, Report No HMIP/CPR2/41/1/38, October 1995

PCBs Name Name Name

Coal Cement Manufacture - Fuel Use

Data supplied from the British Cement Association

AEA Estimates based on Dyke 1997

Scrap Tyres Cement Manufacture - Fuel Use



Waste Oils Cement Manufacture - Fuel Use



Coal Lime Manufacture - Fuel Use

AEA estimates AEA Estimates based on Dyke 1997

PI - Pollution Inventory. SPRI - Scottish Pollution Release Inventory. ISR - Inventory of Sources and Releases (Northern Ireland). HMIP - Her Majesty's Inspectorate of Pollution

Emissions to Air: Dioxins The emissions of dioxins to air currently quoted within the NAEI are based on the Pollution Inventory data, which will give absolute emissions to air. To try and ratify these figures production figures for clinker are taken from the BCA and used to derive an emission factor as the intermediary step between activity and emission. Table 1.14 shown below gives comparison of the emission factors derived within the NAEI against other core literature emission factors based on µg I-TEQ/t of clinker produced. The figures quoted suggest that the emission factor ranges between 0.2 and 0.6 µg I-TEQ/t.

The emission factors used within the NAEI largely fall within this range, although for the last four years of the time series the emission factors are greater than 0.6 µg I-TEQ/t with values peaking in 2003 and 2004 at 1.59 and 2.24 µg I-TEQ/t respectively. This also reflects the unusually high emission of dioxin in 2004 quoted as 24.2 g I-TEQ, noting that the other years range from 8.5 to 0.9 g I-TEQ. As stated the values quoted are based on pollution inventory data with values for 2004 possibly being erroneous.

The emissions of dioxins quoted show a decreasing trend (8.5 g I-TEQ in 1990 to 0.9 g I-TEQ in 2006) even against the increasing quantities of scrap tyres used as fuel within the industry. This is likely due to the stringent abatement technology and improvements in process practice. The BIPRO waste report states that much of the dioxin emissions from cement manufacture can be significantly reducing by the quick cooling of exhaust gases and recycling of CKD (cement kiln dust) back into the process wherever possible.


46 AEA

Table 1.14 Quoted emission factors for dioxin emissions to air from cement manufacture.

Reference Source Emission Factor as g I TEQ/t of clinker

UNEP toolkit – class 3 0.6 µg TEQ/t

UNEP toolkit – class 4 0.05 µg TEQ/t

UNECE guide book 0.2 µg TEQ/t

IPPC BREF <0.2 – 1 µg TEQ/t

US EPA – Worst Case Scenario – Heavily contaminated wastes

20.9 µg TEQ/t

US EPA - default 0.27 µg TEQ/t

NAEI 1990 - 2006 0.15 – 2.2 µg TEQ/t

NAEI - average 0.81 µg TEQ/t


The NAEI does not currently quote emissions of HCB from the cement sector. However the UNECE guidebook quotes an emission factor of 11 µg /t of cement produced. It is important to note that cement clinker and cement are different things. Gypsum is added to cement clinker at 5% w/w as a set retarder before blending to give the finished product. The activity data supplied by the BCA is for clinker, and therefore it is possible to extrapolate activity data as finished cement from this dataset. As with PCBs there may be some concern here using the same emission factor for all production and all years noting that the content of waste and quantities of finished goods will vary vastly from site to site and year to year. The emissions quoted have been done so to act as a guide and it should be understood that the level of uncertainty will be high.

The quoted emissions to air will be small and decrease across the time series ranging from 0.15 kg in 1990 to 0.12 kg in 2006. Pesticide use remains the key source for HCB emissions within the inventory.


The emissions of PCB from cement manufacture conversely to the calculations done for dioxin are fuel focused, noting that key fuel for the sector will be coal and that waste fuels only make a small proportion of the total fuel use. This stated the use of scrap tyres within the sector has steadily increased across the time frame from 0.6 kt in 1990 to 76.7 kt in 2006. This is in comparison to coal use (875.2 kt in 2006). As with dioxin the emissions of PCB to air decline across the time series from 2.24 Kg in 1990 to 0.95 kg in 2006 while production levels have only decreased slightly and use of wastes such as scrap tyres have increased. This would reflect an improvement both in abatement technology as well as process practice to reduce such emissions. As cement manufacture requires high temperatures within the furnace, which would likely destroy the formation of POPs, the key aspects of POPs generation will be during the start up, and shut down of furnaces, and the slow cooling of exhaust gases.


The main potential waste from cement production (that is relevant to POPs) is cement kiln dust (CKD), which is collected in the electrostatic precipitators and filters that are used to control particulate emissions. The proportion of CKD that is recycled into the system is the key aspect to take into account in quantifying releases to land or residues that are recycled or disposed to a controlled landfill. In the past, some cement plants were unable to recycle all CKD because of limits to the concentrations of some elements into the process to ensure product quality. Some CKD would have been disposed at controlled landfill, and some used in agriculture because of its lime content.

Within more modern production it is expected that a high proportion of CKD is recycled to maximise output. It has been assumed as a worst case that prior to licensing that a proportion of CKD was disposed to land. The report on the European dioxin inventory (LUA 1999) indicates that the amount of CKD not recycled could, in general, be up to 35 kg of CKD per tonne of cement produced. A wide range of emission factors have been summarised in Dyke (1997) as 0.001 to 30 ng I-TEQ/kg CKD, and a concentration of 10 ng I-TEQ/kg CKD have been adopted to estimate the potential releases to land before 1998. This quotes the pre-1998 dioxin emissions as between 4.62 g I-TEQ and 3.50 g I-


AEA 47

TEQ. No calculation has been made on the split between quantities consigned to landfill and quantities recycled into other industries.

Releases to Water

Releases to water will only occur where wet abatement is used in the process. It is believed that the majority of cement plants within the UK use a dry process and as such no estimate has been made for emissions to water. Any emissions would be expected to be negligible.


There are unlikely to be significant changes to POPs emission factors from the production of cement, except potential further improvements in environmental protection, which would reduce emission factors further. This sector will come under closer attention in the UK if there are any significant changes to the nature of waste used as fuel within the sector.

1.6.3 Results

The graph below summarises the emission to air, land and water from the cement and lime sectors combined, and a table of total 2A1 emissions is also given above.


AEA 49

UK POPs Emissions: 2A1 Cement & Lime, 1990-2006

0.00

5.00

10.00

15.00

20.00

25.00

30.00

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

g-I

TE

Q D

ioxin

Kg

B(a

)P,

I(123-c

d)P

0.000

0.500

1.000

1.500

2.000

2.500

kg

PC

B a

nd

HC

B

DIOXIN AIR DIOXIN LAND DL PCB AIR PCB AIR HCB AIR

Table: 2A1 Cement and Lime Manufacture POPs Emissions in the UK, 1990-2006


50 AEA


Currently within the NAEI a disparity exists between the calculations used to gauge the emissions of dioxins and PCBs. While the activity data in each case has come directly from the operators and so is likely to be highly accurate, the emission factors for PCBs are quantified based on the fuels burnt while the emission factors for dioxins are derived from the pollution inventories.

The use of fuel focused emissions allows trends within waste fuels to be used to estimate emissions however there is not the monitoring date to show that changing fuel has a significant effect on emissions given the variability in the emission measurements.

There are no UK emission measurements at cement kilns for HCB. The UNECE guidebook provides an emission factor for HCB emissions based on the quantity of cement produced rather than the fuels used. As this emission factor is a single value used for all years the level of uncertainty will be very high.

The emissions of all U-POPs from this sector are low and decrease across the time series between 1990 and 2006. This is the result of the closure of some more polluting kilns and improved abatement at others.

1.6.5 References

• British Cement Association, www.cementindustry.co.uk/


• Pollution Inventories (England and Wales, Scotland, and Northern Ireland)


• UK NAEI 1990 – 2006

• UNECE guide book (2007)


• US EPA – ‘An inventory of sources and releases of dioxin like compounds in the US 1987, 1995 and 2000’


AEA 51

1.7 Minerals: Lime Production (2A1)


The lime production process involves the grinding and ‘heating of quarried limestone, which is principally calcium carbonate (CaCO3) to produce Quick Lime, calcium oxide (CaO). The rock used may also contain impurities such as sand and organic matter. It can then be further treated by the addition of water, a process called slaking to give rise Slaked Lime calcium hydroxide (CaOH). The finished products can then be packaged and distributed for use.

Emissions of POPs to air, land and water depend on the type of fuel used and the potential abatement equipment in place, noting that any use of wet scrubbers can generate contaminated water that would undergo waste water treatment.

The UK lime industry is concentrated on a small number of sites that produce around 1.6 Mt of lime per annum (British Lime Association). This sites will include quarrying processes as well as use of kilns and speciality processes for bespoke products.


The fuels used for baking lime include natural gas, coal and coke (BREF note). It is assumed that emissions of POPs from natural gas firing are unlikely. The BREF note quoted states that it is also possible to burn waste fuels, typically oils and plastics, with furnace operating temperatures between 900 - 1500 Celsius. Energy costs are a very significant part of the costs of production and hence operators, will, within the constraints of producing the product seek flexibility between fuels. Currently the NAEI does not include an estimate for the use of waste fuels in lime production, a practice more commonly associated with cement manufacture, and it is unknown whether this practice is significant in the UK industry.

The emission estimates within this sector have similar sources to those seen in the cement sector. Dioxin emissions for lime are based on the pollution inventory as assumed output, and estimates made to derive activity data and then emission factor in kind. The dioxin emissions from the use of coke are based on literature emission factors (HMIP) against estimated activity data, likely made against Lime output and fuel use for similar sectors such as cement manufacture. The uncertainty within the activity data will therefore be high as a result.

The emission of PCBs is based on Dyke’s (1997) emission factor against the same estimates for activity data in coal use. These figures will also have a high uncertainty although the emissions from the lime sector are likely to be small within the overall inventory.

A full table of reference sources for activity and emission factors to air used within the NAEI is quoted within table 1.13 shown in the cement manufacture chapter.


The emissions of dioxin from coal are based on the pollution inventories as output against estimated activity, which is then used to derive emission factors. As the dioxin emissions quoted in the PI data vary year on year, while the activity data remains relatively stable, the emission factors generated also vary significantly with a wide range from 0.16 ng I-TEQ/ Mt of coal burnt to 20.66 g I –TEQ/Mt. This possibly reflects the variability in the fuels used, the process feedstocks and the uncertainty in the emission measurement.

As a further means of comparison, the UNEP toolkit (2005) provides emission factors of dioxin to air from lime manufacture based on activity as tonnes of finished product. While not a direct comparison it provides a useful insight to the values quoted within the NAEI. The UNEP values are quoted as 0.07 g I-TEQ/Mt for lime production with good dust abatement and 10 g I-TEQ/Mt for lime production with no abatement. The emissions of dioxin for this sector however remain small ranging from 0.028 g I-TEQ to 0.868 g I-TEQ over the period studied.


52 AEA


No information has been obtained on HCB emissions.


Emissions of PCBs to air are sourced to coal combustion and are based on the same set of estimated activity data for dioxins combined with the emission factor quoted by Dyke, 1 kg/Mt of coal burnt. The emissions of PCB are small by comparison to other inventory sectors, however as has already been stated a large amount of uncertainty exists in the results.


Lime production has the potential to generate kiln dust, which can then be contaminated with POPs. The activity data used and reported thus far has been based on fuel use and as such no calculation can be made for releases to land for this sector. Emissions in this case are expected to be small especially as process change tends to lead to reduce quantities of kiln dust.

Releases to Water

The emission of POPs to water would only be likely where wet abatement has been used, noting that the slaking process may also generate some effluent but typically the water added is adsorbed into the product. UK plant currently are not thought to have wet abatement.


Within the current estimates there are unlikely to be significant changes to POPs emission factors from the lime plants noted other than from significant changes in fuel use, and potential further improvements in environmental protection which would reduce emission factors further.

1.7.3 Results

The graph and table of results provided in the section above on cement manufacture (also in Sector 2A1) includes the emissions data for lime production.


While the emissions from this process are combustion related fuel statistics are not sufficient to understand the formation and emissions of U-POPs from this source. Hence the data from the regulator’s Pollution Inventories is very important.

There is a lack of activity data surrounding the generation of kin dusts are their fate. While these materials are likely to be recycled or consigned to landfill, no estimates can be made of environmental releases or transfers.

The emissions of POPs from the lime manufacture sector are likely to be small in comparison to other sectors and while the uncertainties in this sector are likely to be high other sectors make take priority for review.

1.7.5 References

• European Commission (2007) .BREF note for Cement and Lime Manufacturing Industries

• British Lime Association - http://www.britishlime.org/



• UK NAEI 1990 - 2006

• UNEP Toolkit (2005) Standardized Toolkit for Identification and Quantification of Dioxin and Furan Releases


AEA 53

1.8 Other Minerals Production (2A7) (Glass, Brick, Tiles, Ceramics and Asphalt)


The following chapter will incorporate the rest of the mineral production sector, which comes under the NFR code ‘2A7’. This will include the production of asphalt, brick, ceramics, glass and tiles within the UK.


The activity data used across this entire sector is based on estimates against either UK national statistics or sector specific data from other sources. As some of the data are estimates then the level of uncertainty will be high. Relevant activity data for these sectors is difficult to identify, particularly in the case of both glass and ceramics, which cover a variety of different products manufactured by different processes and techniques.

The quantities of asphalt manufactured and used will likely reflect demand in road maintenance and new road building. The figures currently quoted within the NAEI show a decline from 26.4 Mt in 1990 to 20.1 Mt in 2006. A full table of the reference sources used for activity and emission factors of dioxin to air are quoted in Table 1.15.


The emission factors used for dioxin emissions to air come from the HMIP report (1995) and as such may not reflect improvements to process technology or abatement Emissions to Air: Dioxins

The emission factors used for dioxin emissions to air come from the HMIP report (1995) and as such may reflect out of date figures for the more recent years of the time series. The emission factors used for glass have been modified since 1998 to take into account greater control over the process. Typically the potential for dioxin emissions from glass production is low because of the long residence times in high temperature conditions, although chlorine can be introduced via fuels and raw materials, and therefore there is some potential. However most modern glass production processes utilise gas and electric as the chief fuel source so dioxin emissions would be very low.

The emission factors quoted for glass range from 3.5 µg I-TEQ/kt in 1990 to 2.1 µg I-TEQ/kt in 2006, while production has been estimated to have increased from 3.1 Mt in 1990 to 4.1 Mt in 2006. The increase in production suggests a growth in the speciality glass market (0.226 Mt up to 0.386 Mt) while container glass (2.29 Mt in 2006) and flat glass (1.3 Mt in 2006) remain the key production products. The emissions of dioxins from glass remain low decreasing slightly from 0.011 (1990) to 0.009 (2006) g I-TEQ. Within the realms of uncertainty this would make the trend for glass questionable and the emissions themselves potentially lower than quoted.

The dominant feature of the sector is the production and use of asphalt. It is key at this juncture to define the terms used given variation between European and American products. Within Europe the term ‘Asphalt’ is used to describe a bituminous product that contains varying amounts of aggregate (depending on its purpose) and is chiefly used to build and maintain roads. The term ‘Bitumen’ describes a heavy oil tar product, which is used at elevated temperatures particularly in roofing materials for some buildings. In the USA the term ‘Asphalt’ is used to describe the bituminous product and ‘Asphalt Cement’ is used to describe the product containing aggregate. For the purpose of the inventory all terminology will reflect the European standards.


The emission factors used for dioxin emissions to air come from the HMIP report (1995) and as such may reflect out of date figures for the more recent years of the time series. The emission factors used for glass have been modified since 1998 to take into account greater control over the process. Typically the potential for dioxin emissions from glass production is low because of the long residence times in high temperature conditions, although chlorine can be introduced via fuels and raw materials,


54 AEA

and therefore there is some potential. However most modern glass production processes utilise gas and electric as the chief fuel source so dioxin emissions would be very low.









The emission factors quoted for glass range from 3.5 µg I-TEQ/kt in 1990 to 2.1 µg I-TEQ/kt in 2006, while production has been estimated to have increased from 3.1 Mt in 1990 to 4.1 Mt in 2006. The increase in production suggests a growth in the speciality glass market (0.226 Mt up to 0.386 Mt) while container glass (2.29 Mt in 2006) and flat glass (1.3 Mt in 2006) remain the key production products. The emissions of dioxins from glass remain low decreasing slightly from 0.011 (1990) to 0.009 (2006)


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g I-TEQ. Within the realms of uncertainty this would make the trend for glass questionable and the emissions themselves potentially lower than quoted.



The emission factors used for dioxin emissions come from the HMIP report (1995) and reflect the absence of more recent emission measurements in the public domain. The emission factors used for glass have been modified since 1998 to take into account greater abatement installed on processes to reduce particle emissions which are thought to be control over the process. Typically the potential for dioxin emissions from glass production is low because of the long residence times in high temperature conditions, although chlorine can be introduced via fuels and raw materials, and therefore there is some potential. However most modern glass production processes utilise gas and electricity as fuel source so dioxin emissions would be very low.

The emission factors used for glass have been modified since 1998 to take into account greater control over the process The emission factors quoted for glass range from 3.5 µg I-TEQ/kt in 1990 to 2.1 µg I-TEQ/kt in 2006, while production has been estimated to have increased from 3.1 Mt in 1990 to 4.1 Mt in 2006. The increase in production suggests a growth in the speciality glass market (0.226 Mt up to 0.386 Mt) while container glass (2.29 Mt in 2006) and flat glass (1.3 Mt in 2006) remain the key production products. The emissions of dioxins from glass remain low decreasing slightly from 0.011 (1990) to 0.009 (2006) g I-TEQ.

Typically the potential for dioxin emissions from glass production is low because of the long residence times in high temperature conditions, although chlorine can be introduced via fuels and raw materials, and therefore there is some potential. However most modern glass production processes utilise gas and electric as the chief fuel source so dioxin emissions would be very low

The dominant source in this sector is the production and use of asphalt. Within Europe the term ‘Asphalt’ is used to describe a bituminous product that contains varying amounts of aggregate (depending on its purpose) and is chiefly used to build and maintain roads. The term ‘Bitumen’ describes a heavy oil tar product, which is used at elevated temperatures particularly in roofing materials for some buildings.

Asphalt, unlike other mineral products within this sector will be mixed and used while still hot. Controlling and maintaining optimum working temperatures while on site can prove difficult dependant on the environmental conditions. Further more the possibility for contamination with materials on old road surfaces or contaminated fuels mean the potential for dioxin emissions from asphalt use are higher than the other mineral products in this sector.

The emission factor quoted by the HMIP report (1995) and used within the NAEI is 0.047 µg I-TEQ/tonne produced. This compares to the UNEP toolkit (2005), which quotes emission factors ranging from 0.007 to 0.07 µg I-TEQ/tonne produced, depending on levels of abatement and contamination of raw materials.

The emissions to dioxins quoted within the current inventory show a decline from 1.24 to 0.95 g I-TEQ between 1990 and 2006, this reflects the decline in asphalt production.

Asphalt remains the dominant feature within the sector, total dioxin emissions to air from NFR 2A7 in 1990 were 1.29 g I-TEQ (1.24g I-TEQ from asphalt) and in 2006 0.98 g I-TEQ (0.95 g I-TEQ from asphalt).


No data are available for HCB emissions from glass production, although the emissions would be expected to be low.


56 AEA

Table 1.15 Reference Sources used within the inventory for 2A7 Other Mineral Manufacture


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No data are available for PCB emissions from glass production, although the emissions would also be expected to be low.


Several of the production processes used within the sector have the potential to generate dusts (brick dust, glass dust etc). However, the quantities of dust generated are likely to be small and whether possible recycled back into the process. The application of asphalt to roads may potentially contain some contamination of land. No calculations have been made for releases to land from this sector.

Releases to Water

Significant releases to water would only be expected if wet scrubbers are used and while this may be true of some operations the majority are likely to use dry process abatement such as ESP (Electro Static Precipitators). No concentration data are available on releases to water.


Emissions are unlikely to increase from this sector unless there is a significant change in the quantity and quality of fuels used. More likely, the associated dioxin emissions are likely to decline, although this will strongly be linked to asphalt manufacturing demands.

1.8.3 Results

The graph below summarises the emission to air, land and water from the sum of all sub-sectors within NFR 2A7, which includes glass manufacture, ceramic, brick and tile manufacture, and asphalt manufacture. The second graph shows the emissions from the individual industries and a table to summarise the emission trends across the 2A7 Sector is also shown below.

Data Quality, Uncertainties and Recommendations for Improving the Inventory

The activity data used within the current sector has been based on estimates for all industries and processes. Emission factors are based on a source which is 15 years old and didn’t reflect a wide selection of measurements at the time (HMIP 1995) with the only modification being a reduction in emission factor for glass manufacture. Without more recent measurements being available this is the only approach that is feasible. The UNEP toolkit (2005) provides default emission factors for dioxin to air from the key source area (asphalt production) these are in agreement with those from the HMIP report.

However as the emissions associated with this sector remain low in comparison to other sectors where combustion activities are more likely to generate POPs emissions funding for measurements is unlikely.

The uncertainties for emissions to land are also high, noting that several processes within brick, glass, tiles and ceramics will generate dusts. However the levels of contamination while likely to be very small, have not been measured, and in many cases the dust is either recycled into the production process or disposed of to controlled landfill and so does not lead to an environmental release.

The chief recommendation for this sector is to improve the activity data surrounding the production of asphalt and this can be achieved by communication with industry stakeholder groups.

References


• UK NAEI 1990 – 2006



58 AEA

UK POPs Emissions: 2A7 Glass, Brick, Tile, Ceramics and Asphalt, 1990-2006

0.000

0.200

0.400

0.600

0.800

1.000

1.200

1.400

1.600

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

g-I

TE

Q D

ioxin

DIOXIN AIR


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UK Dioxin Emissions (minus asphalt): 2A7 Glass, Brick, Tile, Ceramics, 1990-2006

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

g-I

TE

Q D

ioxin

Glass Manufacture Brick and Tile Manufacture Ceramic Manufacture

Table: 2A7 Other Mineral Manufacture POPs Emissions in the UK, 1990-2006


60 AEA

1.9 Other Chemical Manufacture (2B5)

1.9.1 Sector Description (NFR Code 2B5)

NFR 2B5 covers all other sectors of chemical manufacture not covered under the earlier ‘2B’ sectors. This includes the manufacture of chlorine, trichloroethylene, tetrachloroethylene and Poly Vinyl Chloride (PVC) processes which may lead to the formation of dioxins and HCB. Please note that this section will focus on the emissions linked to manufacture, and emissions from solvent using processes such as dry cleaning and textile production are covered in sections 3B and 3C.


Table 1.21 shown below shows the references used for activity statistics and emission factors. Chlorine Manufacture The manufacture of chlorine is carried out by the electrolysis of brine and produces chlorine and caustic solution (BREF). The fate of the dioxins is principally to the sludges produced in the cells. The emission of dioxins to air is expected to be less likely given that the electrolysis process is carried out at ambient temperatures (BREF). In the UK the majority of chlorine production is currently carried out at Runcorn which is transitioning from mercury based cells to mercury free technologies. Dyke (1997) quotes emission of dioxin to land in the same year as 6 g I-TEQ, from the disposal of sludges to land, either onsite or to landfill. The generation of dioxin within sludges is believed to be related to the use of graphite anodes in the mercury process, with the use of graphite being steadily phased out since the 1980s in favour of alternatives such as titanium (BREF). Strandell (1994) states an emission factor of 39.9 ng I-TEQ/kg of sludge from use of titanium anodes. The UNEP toolkit default values based on graphite anodes are 20 µg/kg of sludge or 1 g I-TEQ/Mt of chloralkali produced. As of 2005 the plant at Runcorn has undergone a significant development plan to switch production from the mercury process to the membrane process (Ineos Chlor). This switch in production type will significantly decrease emissions of dioxin to sludge. The NAEI currently holds activity data for Chlorine production based on production capacity not annual production. UK capacity stated for 2006 was 1.02 Mt, data from EuroChlor states Chlorine production for 2007 as 0.774 Mt, with 0.767 Mt coming from Runcorn. The current estimates have been based on capacity as a worse case scenario, given that while capacity data is complete for all years production data is not. This is used with the emission factor from Dyke. PVC Manufacture The production of PVC is based on a series of intermediate steps to produce the final product. This includes the production of Ethylene Dichloride (EDC), which then undergoes a thermal cracking process to produce Vinyl Chloride Monomer (VCM), before polymerisation to PVC. There is potential for the generation of dioxins with the manufacture of both EDC and VCM, with the most likely source being the oxychlorination step in the manufacture of EDC. The major release of dioxins is through the generation of contaminated sludges (BIPRO), although the thermal nature of the process means that there may also be releases to air, which are not currently estimated as the process takes place in a closed reactor. It is possible that there are occasional releases for safety reasons however emissions have not been estimated. Given the reactive nature of


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chlorine it is not frequently transported and so the manufacture of chlorine and related products are usually done on the same or neighbouring sites. The leading UK producer is based also at Runcorn . The generation of contaminated sludges will likely be handled on site, either through a process of waste water treatment including dewatering and then incineration of waste on site or disposal to landfill. The current estimates will focus only on the generation of sludges only with no estimate made for quantities incinerated/land filled. The BIPRO waste report (2005) quotes emission factors for dioxin of;

• 0.95 µg I-TEQ/t of EDC as emission to air (based on the UNEP toolkit),

• 0.5 ng I-TEQ/g for contamination of sludge (assuming sludge generation as 200 g/t of EDC), and

• 0.5 µg I-TEQ/t of EDC to water. LUA (1999) quotes an emission factor for water as 1 µg I-TEQ/t., but this is believed to be the working limit and actual emissions will be lower. Activity data for UK production of EDC and VCM has been difficult to source, The BIPRO report (2005) quotes UK production for 2004 as 1.07 Mt for EDC. LUA (1999) quotes UK production for 1998 as 0.96 Mt. In lieu of other data these figures have been used for UK activity.

Table 1.21 Reference Sources used within the inventory for 3D- Solvent manufacture

Trichloroethylene and Tetrachloroethylene As both trichloroethylene and tetrachloroethylene involve chlorinating processes at elevated temperatures, the resulting process emissions (to air) are likely to contain dioxins and other POPs. The activity data used to make the calculations within the NAEI has been based on estimates from industry production data. Production data are difficult to obtain from independent sources. Production rates of both chemicals have declined since the start of the time series as a result of usage controls of the solvents particularly in the case of trichloroethylene, which is now known to be a carcinogen (HSDB). Future trends would suggest that their production will continue to decline and as such the estimates currently used may represent the upper bound of future emissions.


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Emissions to Air Dioxins Emissions from the manufacture of PVC and its intermediaries have focused on the oxychlorination process in manufacture of EDC. While it is possible that emissions of dioxin from EDC cracking in the manufacture of VCM are likely, no emission factors were found. It is believed that the manufacture of EDC is the chief source (BIPRO). Even though, the emission to air from this process are small varying between 0.78 g I-TEQ (1990) – 1.05 g I-TEQ (2006). The uncertainty in these figures is likely to be high, with emissions decreasing as levels of abatement improve.

HCB The emissions to air have been based on estimates for activity, noting a steep decline in production, and emission factors from Duiser’s 1989 report. The emissions factors in this case are unlikely to represent current practices for 2006. However, as production is declining these are likely to be conservative (upper bound estimates) for the more recent years of the inventory. The estimates quote a decline from 204 kg of HCB in 1990 down to 23.4 kg in 2006, which are largely from decreasing production but also likely from improvements in process practice and abatement. Residues / Releases to Land

The production of chlorine and EDC will generate sludges contaminated with dioxins. No estimate has been made in this case to the treatment of such waste. The Runcorn site now has a hazardous waste incinerator to dispose of on-site generated wastes. Previously sludges were disposed of in controlled landfill sites in former salt mines. Dyke (1997) quotes the emission in this case for the UK as 6 g I-TEQ per annum. In contrast based on the UNEP emission factors the emission is calculated as 0.86 g I-TEQ per annum, and this reflects the large uncertainty in this case. The Dyke figures have been retained as UK specific. The figures for emissions to land from EDC manufacture low at less than 0.1 g I-TEQ for the majority of years. Releases to Water There is expected to be a small release of dioxin contaminated water from the manufacture of EDC, which in the current estimates ranges from 0.40 - 0.55 g I-TEQ per annum. As with other estimates the uncertainty will be high, and emissions to water from this sector are likely to remain low. Potential Future Changes It is expected that emissions from this sector will continue to decrease as process practice and abatement improves.

1.9.3 Results

A graph of results for emissions from the sector 2B5 is shown on the next page, together with a full table of emissions.


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UK POPs Emissions: 2B5 Other Chemical Manufacture (including Chlorine and PVC), 1990 - 2006

0.00

50.00

100.00

150.00

200.00

250.00

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Year

Kg

HC

B

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

g I

-TE

Q D

ioxin

HCB AIR DIOXIN AIR DIOXIN WATER DIOXIN LAND

Table: 2B5 Other Chemical Manufacture POPs Emissions in the UK, 1990-2006


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The data used to calculate emissions for the current sector has largely been based on estimates. The current activity data quoted for chlorine production has been based on capacity figures for the industry rather than actual productivity, and this can be improved through communication with the operators or industry groups. There is also a high degree of uncertainty with regard to emissions to land. The manufacture of both chlorine and EDC for PVC will generate waste sludges. Within the current estimates no detail has been made to how these sludges are handled and this is another area which needs to be refined further. In the case of trichloroethylene and tetrachloroethylene, the manufacture and use of these goods has declined over the time series as health fears have driven the need to find alternative products. The data surrounding the quoted emissions for these processes have been built on estimates of activity data against emission factors which are likely out of date for modern production processes. This means that the uncertainty in the emissions quoted will be high. However, as stated the industry sector has noted a decline in production across the time series which is likely to continue and therefore the emissions will also continue to decline. However the emissions from this sector are still small compared against other POPs sources and other parts of the inventory are likely to take priority.

1.9.5 References

� BREF Note (IPPC) for chlor-alkali production, and Polymer production: http://eippcb.jrc.es/reference/

� Duiser, J.A., Veldt C. 1989, Emissions to the Atmosphere of PAH, PCN, PCB, Lindane and HCB in Europe, TNO Report 89-036 Apeldoorn The Netherlands.

� HSDB – Hazardous Substances DataBase. http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?HSDB

� LUA 1999 – Releases of Dioxins to Land and Water in Europe � BIPRO (2005) Study to facilitate the implementation of certain waste related provisions of the

regulation on Persistent Organic Pollutants (POPs). � UK NAEI 1990 – 2006


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1.10 Metal Processes : Iron & Steel (2C)

1.10.1 Sector Description (NFR Code 2C)

This sector covers the manufacture of iron and steel, an energy intensive process which is the largest source of dioxins to air from the sintering process as well as from electric arc furnaces. While it does include all the elements of steel and iron production such as foundries and steel rolling mills.

The UK iron and steel market is made up of three integrated iron and steel plant owned by Corus; Port Talbot, Redcar and Scunthorpe which turn raw materials such as iron ore and coal into steel and a handful of large scale plants. And a larger number of merchant electric arc plant which take recycled steel and iron, melt it and adjust the composition to those required by the market. Then there are a number of other works associated with casting plant which melt steel and iron to cast into products.


The activity data in the current inventory relate to both fuel use, quantities of raw material used (e.g. iron ore ) and quantity of finished product (steel produced from basic oxygen furnaces). The integrated steel works contain a number of process plant with individual emission characteristics and release routes. The coke works referred to earlier make coke. Sinter plant combine coke and iron ore with flux into pellets for use in the blast furnace, the blast furnace converts the iron ore into liquid iron, the basic oxygen furnaces then convert the liquid iron into steel.

Activity data for Production processes have been sourced largely from the Iron and Steel Statistics Bureau (ISSB) and communication with the Corus Group. Activity data for fuel use has been largely sourced from DUKES. While data for the integrated works is of high quality been derived from the one operator in the UK activity data for grey/cast iron is more uncertain being difficult to source, as production is spread across a number of smaller operators.

A full table of references for activity data and emission factors to air is shown on the next page.


The emission of dioxins to air from iron and steel production are dominated by process emissions as oppose to fuel related emissions. The emission factors for sintering and pelletising of iron ore, and electric arc furnaces for secondary steel production are derived from the pollution inventories and change year on year to reflect the improvements in emission control resulting from the IPPC permitting programme. The emission factor quoted for sintering and pelletising in 1990 is 3.13 g I-TEQ/Mt of iron ore consumed, dropping to 2.83 g I-TEQ/Mt in 2006. The emission factor for electric arc furnaces is higher; in 1990 this is quoted as 5.99 g I-TEQ/Mt of steel produced, dropping to 2.34 g I-TEQ/Mt in 2006.

While the emission factor for electric arc furnaces is higher, the quantity of primary steel produced is significantly higher than secondary steel making. The ISSB estimates for 2007 quote 11.3 Mt of primarily steel produced from 14.5 Mt of iron ore and 1.9 Mt of scrap steel, and 3 Mt of secondary steel produced from 3.3 Mt of scrap steel. hence the emissions from sintering are the dominant source in the sector.

The emission of dioxins to air from Iron and Steel is significant within the inventory. The emissions to air from Iron and Steel in 2006 are the second largest source (behind open waste burning 6D) with 38.4 g I-TEQ quoted, of which 30.3 g I-TEQ from sintering and 6.4 g I-TEQ from electric arc furnace being the key elements.

One issue that is noted within the NAEI is that the NAEI quotes emissions for PCB from both the sintering process and the basic oxygen furnace, both part of a modern integrated steel works. However emissions for dioxin to air are quoted for sintering only. As these POPs are formed as a result of the process rather than any contamination it would seem probable that both processes should emit both dioxins and PCBs. No literature emission factors for BOS plant were obtained.


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Table 1.16 Reference Sources used within the inventory for 2C Iron and Steel manufacture

There is also continued uncertainty within the emissions from grey iron production.; in this case the emission factor comes from an old estimate and is used against estimates of production, making the level of uncertainty extremely high. The emission factors used (as with sintering and electric arc furnace) decline year on year from 2.35 g I-TEQ in 1990 to 1.75 g I-TEQ in 2006. This seems reasonable given the improvement in abatement required by the industry during the early to mid 1990s. As a comparison source the UNEP toolkit (2005) quotes emission factors between 0.03 and 10 g I-TEQ dependant on process. This puts the emission factors used on the middle to lower end of this scale, while no process information has been readily found and abatement will vary between sites.


No emission factors for HCB from iron and steel production have been found.


Emissions of PCB to air are dominated by process emissions as oppose to fuel related emissions. The emission factors used for process emissions have been sourced from Dyke (1997). As scrap steel is used as the raw material in secondary steel production it is possible that PCBs may enter the process as well as being formed within it. However precautions are taken to prevent this happening. However


68 AEA

secondary steel production dominates the PCB emissions to air as a result of the high emission factor. The emission factor quoted within the NAEI for PCBs from secondary steel manufacture range from 98.5 kg/Mt of liquid steel in 1990 down to 47.28 kg/Mt in 2006.

The emissions of PCBs from Iron and Steel make up a significant proportion of the overall inventory, and are estimated to be the second largest source. In 1990 PCB emissions to air were calculated to be 525 kg (of which 447 kg comes from secondary steel production), in 2006 this was done to 175 kg (of which 128 kg comes from secondary steel production). This decline is caused by both improved abatement and a decline in activity across the time series. Current uncertainty in the economy may lead to a significant reduction in production and hence emissions.


The UNEP toolkit (2005) quotes default emission factors for the generation of ‘residue’ from the production of iron and steel. This emission will be dust from the production process. It should be noted that these emissions are for total production quantities; no estimates are made regarding quantities lost to landfill, recycled into other industries (such as cement or aggregate) or accidental loss to environment. It should be noted however that the integrated steel works will have a high level of abatement and fugitive release management and the quantities of dust lost to environment from accidental release will be small. The more likely disposal route will be to landfill.

The following emission factors have been used in the current inventory, 0.5 g I-TEQ/Mt of iron for Gray Foundries, 0.003 g I-TEQ/Mt of blast furnace iron for sinter plant production and 1.5 g I-TEQ/Mt of liquid steel for electric arc furnace. The BIPRO (2005) waste report quotes dust generation for the combustion of fuels in power stations; 16 kg/t for grate ash and 84 kg/t for fly ash, which can be used in combination with concentration estimates provided by Dyke (1997) for dioxin (8.7 ng I-TEQ/kg fly ash and 13.5 ng I-TEQ/kg grate ash).

The total release of dioxin to land is 8.54 g I-TEQ in 1990, of which process emissions account for 7.74 g I-TEQ, compared to emissions to air for the same year of 70.46 g I-TEQ. Emissions for dioxin as dust in 2006 are 5.62 g I-TEQ (of which process emissions account for 4.56g I-TEQ ) compared to emissions to air which are 38.39 g I-TEQ.

Dyke (1997) quotes emissions for PCB for both the fuel use in the sector and formation in processes The emission factors quoted are 103 – 776 µg /g of dust, and reflect a wide range of measurement data. In the current estimates a worst case scenario approach has been taken using the maximum value. Even then emissions are low ranging from 56 kg in 1990 to 33 kg in 2006. All transfers are likely to be to a controlled landfill, with little or no loss accidental loss to environment.

Releases to Water

Emissions to water will likely only be generated where ‘wet’ abatement is used in the industry (such as wet scrubbers). Dry dust abatement processes are dominant in the sector but it is possible that some wet abatement may be used at smaller sites for the melting of grey/cast iron, although emissions would be expected to be small. Emissions to water for this sector have not been reported.

Products

There is potential for use of dust generated within iron and steel sector to be used as a raw material in other sectors, such as cement. The quantities re-used are unknown and not calculated here.


The significant changes to POPs emissions from this sector are through further improvements in emission abatement standards and through declining activity in the sector.

1.10.3 Results

The graph below summarises the emission to air, land and water from the iron and steel sector of 2C. A table to summarise the iron & steel emission trends is also shown.

AEA/ ED43184/Issue 1 Review and Update of the UK Source Inventories: Annex 1

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UK POPs Emissions: 2C Iron & Steel, 1990-2006

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

g IT

EQ

dio

xin

s

0.0

100.0

200.0

300.0

400.0

500.0

600.0

kg

PC

Bs

DIOXIN AIR DIOXIN LAND PCB AIR DL PCB AIR PCB LAND

Table: 2C Iron and Steel Manufacture POPs Emissions in the UK, 1990-2006


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The releases from the iron and steel sector are a significant proportion of the inventory total. While activity data for the larger processes are reliable and emission factors based on regular UK measurement programmes, there is far less confidence in the estimates of releases from the manufacture of grey iron.

It is recommended that both the activity data and emission factors for this sub-sector be reviewed.

There is also a high level of uncertainty within the results for emissions to land. It is recommended that the quantity of solid residues exported out side of the plant are reviewed and their destination and contamination levels established.

1.10.5 References

• BREF note for Iron and Steel manufacture, published by the European Commission


• ISSB (Iron and Steel Statistics Bureau) data

• LUA (1999) Releases of Dioxins to Land and Water in Europe


• UK NAEI 1990 – 2006

• UNEP toolkit (2005)


72 AEA

1.11 Metal Processes: Non-Ferrous Metals (2C)


The non-ferrous metal sector covers all metal production except iron and steel.

Within the UK currently primary aluminium is the largest activity with copper lead nickel and tin refining being on a smaller scale. The sector also increases re-melting operations to turn ingots into liquid metal for alloying and casting. In many cases these will be small scale foundries and smelting plants.

The UK also has a healthy market for the production of metals from recycled material; primarily aluminium and lead, where the formation of POPs will depend on the quality of scrap metal used and the process technology and abatement in place.


The activity data is based on the UK Minerals Handbook published by the British Geological Survey which is updated annually across the time series. This data is expected to be robust and present a high level of reliability for compilation of emissions.

The emission factors used as with ferrous metals are a mixture of data from the pollution inventories data, where reports of releases are made, which covers the processes with IPPC permits and measured or estimated releases above the relevant threshold, and literature emission factors and AEA estimates. In particular this has been the case for secondary copper manufacture where emissions of dioxin emissions are thought to be very likely. The use of such estimates while allowing calculations to be made will raise the level of uncertainty within the results, and caution should be taken in how these results are used.

A full table of activity source references and emission factor references are for emissions to air within the NAEI are given in the table on the next page.


Aluminium, copper and lead make up the key parts of the sector with 98% of all quoted dioxin emissions to air in 1990 and 92% of all dioxin emissions to air in 2006.

The activity data used within the NAEI and taken from industry figures produced in the Mineral Handbook and also by the British Geological Survey are shown in Table 1.18 below. These show that historically lead production is smaller than aluminium and copper, with a decline in both the production of primary lead and secondary copper over the time series resulting in 2006 production levels.

Table 1.17 Production quantities for aluminium lead and copper for the UK

Quantities in Mt 1990 1995 2000 2006

Total UK aluminium production 0.73 1.01 1.11 1.13

Total UK lead production 0.46 0.47 0.46 0.34

Total UK copper production 0.56 0.53 0.45 0.29

Each industry in turn will be discussed separately below.

Aluminium

The Aluminium industry is split into primary production and secondary refining where scrap metal is refined for re-use. For primary aluminium manufacture (which will cover both forms of electrolysis – Söderberg and Pre-baked anodes) the data used to make calculations for the NAEI was based on


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Table 1.18 Reference Sources used within the inventory for 2C Non Ferrous Metals manufacture

activity data from industry against emission factors quoted within the HMIP (1995) report. These quote emission factors of 20 g I-TEQ/Mt scaled down to 16 g I-TEQ/Mt in 2006.

Significant improvements have been made in the processes since the emission factor the HMIP report refers to were estimated. The UNEP toolkit and UNECE guidebook both state that the emissions of


74 AEA

dioxins from primary aluminium process will likely be negligible in current processes. The Söderberg process plant at Kinlochleven closed in 1999. The IPPC BREF note also states that the emissions of dioxins from ‘baking’ processes will be unlikely unless chlorine is used, or chlorine contamination is found in the raw material. The anodes are baking from petroleum coke and coal tar pitch neither of which have high chlorine concentrations. The BREF note does state that chlorine can be used as a degassing agent in the casting of aluminium, but measurements taken from exhaust fumes predict that the dioxin emissions would equate to less than 1 g I-TEQ per annum for Europe. To these ends the emissions currently quoted within the NAEI have been scaled to reflect this improvement using the HMIP emission factor for early years and assuming that emissions for 2006 will likely be negligible.

The emissions from secondary aluminium have been found to be more significant although after the first measurements were made in the mid -1990s significant efforts were made to improve the cleanliness of scrap entering the furnace and the effectiveness of the combustion and abatement

processes. The activity data used within the NAEI comes from industry data, while emission factors have been derived based on data from the pollution inventories.

The emission factors quoted by the NAEI range from 12.5 g I-TEQ/Mt of refined aluminium in 1990 to 1.5 g I-TEQ/Mt in 2005 (2006 emission factor is 1.9 g I-TEQ/Mt). The emission factors quoted show a gradual downward trend over the time series with the last 4 years reaching a plateau of around 2 g I-TEQ/Mt. This is in contrast to increasing production with secondary aluminium (0.765 Mt produced in 2006). To act as comparison the UNEP toolkit (2005) gives emission factors for secondary aluminium based on a rating system against abatement with class 1 being poor or no abatement, and the highest class (class 4) being a state of the art plant with high abatement. The UNEP emission factors vary from 0.5 g I-TEQ/Mt for class 4 to 100 g I-TEQ/Mt for class 1. The emission factors used within the NAEI fall between class 2 (Scrap pre-treatment, good system controls, filters with lime injectors) and class 3 (scrap pre-treatment, good control systems, fabric filters with lime injection).

Copper

The copper industry in the UK is dominated by the manufacture of copper alloys. While the UNEP toolkit (2005) states that dioxin emissions are more likely to be produced from the secondary smelting of copper the IPPC BREF notes that dioxins can be formed from alloying during the cooling phase of the process and all exhaust gases should be abated.

The emissions quoted within the NAEI are based on data from the Pollution Inventory to derive emission factors. In the case of copper alloying this produces high emission factors (43.3 g I-TEQ/Mt of copper produced in 1990) for the early part of the time series dropping significantly (0.8 g I-TEQ/Mt of copper in 2006) towards the end of time series. This reflects the improvements made within process practice and control of exhaust emissions as outlined in the BREF note. Emissions for the copper industry fall from 25.28 to 0.25 g I-TEQ between 1990 and 2006.

Lead

As with copper manufacture the emission of dioxins from primary lead production is thought likely to occur during the cooling phase of metal production, and control of exhaust gases will limit the release of dioxins to air (IPPC BREF). In the case of secondary lead manufacture the key precaution to limit dioxin emissions will be to control the plastic content within the raw materials, and any further contamination with chlorine either as fluxes or surface treatments.

The closure of the Avon mouth Lead – zinc smelter during this period led to a significant change in the industrial make up. The decline in primary lead production increases the relative significance of secondary lead production (0.30 Mt of the 0.34 Mt quoted for 2006 comes from secondary production). This in turn may raise the level of uncertainty in the emission estimates, as the quantity of dioxin generated will relate to quality of raw material and the levels of plastic and chlorine contamination in the scrap used for production.

The emission factors for primary lead production come from the HMIP (1995) report and are based on the same reference source used for primary aluminium, and may better represent the early years of the time series, with greater uncertainty placed on more recent years. The emission factors for secondary lead production are based on Pollution Inventory data. The emission factors used within the NAEI vary from 14.4 g I-TEQ/Mt of refined lead produced, to 0.5 g I-TEQ/Mt. In comparison the UNEP toolkit (2005) gives values from 80 g I-TEQ/Mt for class 1 – High content of PVC to 0.5 g I-TEQ/Mt for class 3 – PVC/chlorine free production with high levels of abatement. The emission factors and so the emissions of dioxin for secondary lead production vary year on year but remain low from 2001


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onwards, suggesting that production processes and abatement are more capable of dealing with variable quality in raw materials.


Hexachloroethane (HCE) has formerly been used within the aluminium using sector as a degassing agent being safe for the workforce and easy to handle. However it was known to lead to the emission of HCB as well as HCE to the environment. The use of HCE was banned across Europe in 2003, but environmental concerns and tightening legislation meant that it was little used in the UK after 1998. Van der Most paper (1992) quotes an emission factor of 5000 kg/Mt of secondary aluminium. This figure is also repeated in the UNECE guidebook. The NAEI quotes emissions for HCB from secondary aluminium up to 1998 after which chlorine and sulphur hexafluoride began to be used as alternatives.


No information has been obtained on potential PCB emissions from non-ferrous metals production.


The BIPRO waste report for 2005 quotes the average quantities of dust generated from the manufacture of secondary aluminium as 20.9 kg/t of aluminium. This reference also quotes an emission factor for the contamination of such dust with dioxin of 10 ng I-TEQ/g dust. This means it is possible to use activity data to estimate the dust produced, and in turn the amount of dioxin within such dust. Dyke (1997) also quotes emissions of contaminated dust for copper, magnesium and secondary lead production. It has been assumed that the figure quoted by BIPRO (20.9 kg/t) is constant for other non-ferrous metals, and has been used with Dyke’s emission factors.

There is potential for many of the dust generated in the non-ferrous metal sector to contain significant quantities of valuable metals leading to them being used in other processes as feed material depending on both market prices, metal contents of dusts and the availability of appropriate technology. Little data exists on the impact such transfers may have on the movement of dioxins around the industry.

Releases to Water

The BIPRO waste report 2005 quotes values to calculate the quantity of sludge generated where wet scrubbers are used, and in turn the contamination by dioxin in such sludge. To date no information has been found to indicate whether UK sites use such apparatus.


There are unlikely to be significant changes to POPs emission factors from the non-ferrous production other than potential further improvements in environmental protection, which would reduce emission factors further.

1.11.3 Results

The graph below summarises the emission to air, land and water from the non ferrous metal sector of 2C.


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Table: 2C Non Ferrous Metals Manufacture POPs Emissions in the UK, 1990-2006

UK POPs Emissions: 2C Non Ferrous Metals, 1990-2006

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

160.00

180.00

200.00

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

g-I

TE

Q D

ioxin

0.0

500.0

1000.0

1500.0

2000.0

2500.0

3000.0

3500.0

4000.0

4500.0

5000.0

Kg

HC

B

DIOXIN AIR DIOXIN LAND HCB AIR


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The quality of the activity data within this sector is good. However the detail of the individual processes and how the raw materials are used matters crucially to the formation of dioxins. As this may vary form melt to melt as different products and made and measurements have only rarely been carried out the release estimates for the sector are extremely uncertain. There flow of solid residues between operators is also not understood. The UNEP (2005) toolkit and IPPC BREF note for non-ferrous metals have been used as a guide to gauge the likely emissions and emission factors based on a lack of available emission factors from other sources. While this is useful to help gauge the uncertainty of the emissions quoted it will always be secondary to measured data from UK sites. The Non-ferrous metal sector is significant within the inventory both for the emissions of dioxins, which historically were higher and have declined with reduction in emissions from copper alloying and secondary aluminium production. It is also significant for HCB emissions where the use of Hexachloroethane (HCE) within secondary aluminium production caused this to be the main emission for HCB. Since the use of HCE has ceased this is no longer the case.

1.11.5 References

• British Geological Survey.

• Dyke (1997) – Releases of Dioxins to Land and Water in UK.


• IPPC BREF note for Non Ferrous Metals, (2008), published by the European Commission.


• UK Minerals Handbook

• UK NAEI 1990 – 2006




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1.12 Paper & Pulp (2D1)

1.12.1 Sector Description (NFR Code 2D1)

Although paper production is unlikely to lead to any significant releases of POPs to the atmosphere, dioxins have been detected in sludges and waste water from pulp and paper mills. In which chlorine was used for bleaching the pulp. No UK paper plant have used chlorine for bleaching since before the time period of this study so no estimates are made for this sector.

1.13 Leakage from Electrical Equipment (2G)

1.13.1 Sector Description (NFR Code 2G)

PCB leaks from electrical equipment have been estimated to be the major source of PCB emissions to the environment. The main use of PCBs since the 1970s when open uses were banned, has been as dielectric fluids in electrical equipment such as transformers and capacitors until new closed uses were banned in 1986. In consequence releases to the environment have decreased since 1990 as older equipment is taken out of service, all should have been identified and disposed of by 2000 hence the population of equipment available to leak into the environment has decreased.

It should be noted that there are also some traces of dioxins in PCB dielectric fluid. These arise from both from the original PCB synthesis process and from oxidation during dielectric breakdown events.

PCBs have been regulated for many years. They were found to occur in wildlife initially in 1966 in Sweden and over later years globally. In 1976, the EU introduced controls on disposal of PCBs through Directive 76/403/EEC. The EU later banned the use of PCBs in new facilities in 1985 under Directive 85/467/EEC on restrictions on the marketing and use of certain dangerous substances and preparations. Then in 1996 the EU required Member States to develop plans for existing electrical equipment above a specified size to be removed to a hazardous waste facility, under Directive 96/59/EC on the disposal of PCBs. This was implemented as the Waste Management (Hazardous Waste) Regulations 1998, SI No 163 of 1998. The Marketing and Use Directive requirements are currently implemented by the European Communities (Dangerous Substances and Preparations) (Marketing and Use) Regulations 2000, SI No 107 of 2000, which repeal earlier regulations on the same subject.

PCBs have ceased to be manufactured in the UK since 1977. Manufacturers of electrical equipment were then supplied with alternative dielectric media as replacement products entered the market. However, some countries outside the EU and North America continued to produce these substances until recently and hence products from those countries may have continued to contain PCBs until the mid 1990s although they should not have been imported. Current releases to the environment arise principally from the closed electrical appliances that still exist, as their useful life could be 10-40 years.

Emissions from fragmentising / shredding operations to break down used electrical equipment are covered within a separate section.


The releases of PCBs to the environment from electrical equipment are very difficult to estimate with any accuracy. Since 2000 the only remaining PCB containing products should be those which have not yet been identified. However the lifetime and replacement rates for PCB components and the difficulties and lack of incentive for users in identify and responsibly destroy such components means this may be a significant quantity of material.

Activity data is very difficult to obtain on quantities of PCBs in existing transformers and leakage rates. To these ends the emissions quoted within the NAEI based on Dyke’s (1997) work have been accepted for the current emissions estimates as well. The activity data that Dyke used came from a composition of figures quoted by Harrad et al (1994) and an older APARG inventory, reflecting the age and uncertainty of the figures. As a method of comparison and double check the UNECE Guidebook


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includes emission factors based on a per capita basis, and this method has also been calculated using population data for the UK from the Office of National Statistics.


The data on dioxin concentrations in dielectric PCB fluid from Dyke (1997) gives a concentration in PCB dielectric fluid of 83.5 µg I-TEQ / kg of PCBs. It is assumed that the evaporation rate is the same for PCBs and dioxins so that for every kg of PCBs that are emitted to air, 83.5 µg I-TEQ of dioxins are emitted. Evaporation rates are likely to differ and the emissions quoted should be treated with caution as uncertainty will be high.


The figures used by the NAEI based on Dyke, quote activity data as tonnes of PCB contained within capacitors and transformers, these quantities will decrease over the time series as stock is taken out of commission, noting that 90% were identified and removed by 2000. Emission factors have been assigned to capacitors (1.60 kg/t) and transformers (0.06 kg/t) based on assumed leak rates per year, scaling the same emission factors to all years.

The comparison method is based around the UNECE Guidebook approach. This provides an emission factor to air of total PCBs of 0.13 g/capita/year. This has been assumed to be applicable from 1990 (in the time series) in the UK. This approach should be treated as a very rough guide and will be used as a means of comparison only.

It is assumed that electrical equipment was being taken out of use at 5% per year, reflecting a 20 year average lifetime but allowing for the retention of some equipment well beyond the average, and this emission factor drops by 5% each year. It is assumed that by year 2000 90% of the remaining electrical equipment containing PCBs was identified and removed from situations in which it may have led to environmental contamination as a result of regulatory action. Following the year 2000, a continuing 5% reduction per year of the existing stock is assumed as the remaining equipment containing, but not identified as containing, PCBs is replaced with new equipment. This approach leads to an exponential decline in release but never an elimination of releases.

The table below shows emissions of PCBs to air based on both methods as a means of comparison. This table reflects the uncertainty in trying to calculate estimates for PCBs in electrical equipment. In both cases the results show a decline in quantities with an assumed drop off around 2000 when the majority of larger units should have been identified and removed from service. Using this dual approach it is possibly to quote emissions as a range quoting likely emissions falling somewhere between the two.

Table 1.19 Comparison of PCB emissions to air Dyke’s approach vs UNECE guidebook

Quantities as Kg 1990 1995 2000 2006

NAEI/Dyke approach 5255 3996 797 578

UNECE guidebook approach 7467 5827 460 367


The emission factors quoted for dioxin emissions to air and used by Dyke are referenced from a TNO report from 1995. This work quotes splits for emissions based on total emission of PCBs from leaks and emission of PCB to air from leaks. This makes it possible to assign ratios and proportions of the quantity lost to air and the quantity lost to land and water, assuming that quantities lost to ‘land and water will all be to land. In this case for transformers 12% of emission is to air and 88% of emission is to land. For capacitors the emission to air is 31% and emission to land is 69%.

Within the NAEI only the emission factors for air have been retained and thus the emissions quoted within the NAEI neglect the emission to land and water. Based on the NAEI emissions to air, emissions to land and water (assumed to be land only) can be calculated. This is assuming the quantity released to land is retained in the soil given the insignificant water solubility and high portioning to soil organic matter of PCBs.

As a comparison measure, the UNECE Guidebook indicates that between 20-40% of a leakage evaporates to air. It is assumed the remaining other amount is a direct release to land. The estimated


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emission factor for PCBs to land is therefore 0.43 g/capita/year. It is probable that this fraction is exaggerated to be conservative in terms of atmospheric emissions and so underestimates the likely releases to soil.

The same concentration data for dioxins of 83.5 µg I-TEQ per kg of PCBs is used to estimate the release of dioxins to land.

The table below gives comparison of the emissions witnessed using both the Dyke/TNO method and the UNECE guidebook method. As with air emissions a wide range of emissions are quoted reflecting the difficulty in accurately gauging PCB emissions. As has been suggested it may be useful to use the quoted figures as an upper and lower bound of a range. However within the current estimates the Dyke/TNO values will be accepted on the basis that emission factors have been used with activity data based on tonnes, noting that values based on population may have higher uncertainty.

Table 1.20 Comparison of PCB emissions to air Dyke’s approach vs UNECE guidebook

Releases to Water

The leakage is assumed to pass to land or evaporate to air, and the leakage to water is assumed to be negligible. In practice, some leakage from transformers could directly or indirectly to water-courses but the extent of this could not be estimated.


The leakages of PCBs to the environment will continue to decrease as elderly electrical equipment is replaced with new equipment that does not contain PCBs.

1.13.3 Results

The graph below summarises the emission to air, land and water from all sources within sector 2G, including leakages from electrical equipment and from white goods Fragmentisers. A table to summarise the 2G POPs emission trends is also shown.

Emissions to land as Kg 1990 1995 2000 2006

Dyke/TNO approach 12141 9240 1843 1337

UNECE guidebook approach 24889 19424 1602 1224


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UK POPs Emissions: 2G Transformers & Fragmentisers, 1990-2006

0.000

0.500

1.000

1.500

2.000

2.500

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

g-I

TE

Q D

iox

in (

air

an

d la

nd

)

0

10000

20000

30000

40000

50000

60000

kg

PC

B (

air

an

d la

nd

) a

nd

g W

HO

TE

Q

Dio

xin

Lik

e P

CB

DIOXIN AIR DIOXIN LAND PCB AIR PCB LAND DL PCB AIR


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The leakage from electrical equipment is the major source of PCBs to the environment since the reduction in the mid 1970s of open uses. The estimated releases are very uncertain, because of the lack of information on the quantity of PCB containing electrical equipment remaining in use.

The current study has tried to build upon Dyke’s (1997) original work for the NAEI by re-incorporating the emissions to land and water and using a new method as means of comparison against the existing data. This was based on a method taken from the UNECE guidebook. The UNECE emission factor to air for 1990 is 0.13 g/capita/year, which is a best estimate taken within the range 0.006 to 5 g/capita/year (UNECE Guidebook). Even here the wide range in the emission factors demonstrates the uncertainty.

There is also some uncertainty related to the amount of evaporation, and therefore the release to land and air. The UNECE guidebook quotes a range from 20 – 40% (30% being used for the current estimates) while the TNO study gives values of 12% for transformers and 31% for capacitors.

The best estimate for the release of PCBs to land in 2006 is 1337 kg, based on the Dyke/TNO method (1224 kg by the UNECE guidebook).

1.13.5 References

• APARG (1995), Report on the Abatement of Toxic Organic Micropollutants (TOMPs) from Stationary Sources 1995, AEA Technology, Culham Oxon, UK


• Harrad S J, Sewart A P, Alcock R, Boumphrey R, Burnett V, Duarte-Davidson R, Hallsall C, Sanders G, Waterhouse K, Wild S and Jones K C, (1994), Polychlorinated Biphenyls (PCBs) in the British Environment: Sinks, Sources and Temporal Trends, Environmental Pollution, 85, 131-146

• ONS Population data

• TNO (1995), Technical Paper to the OSPARCOM-HELCOM-UNECE Emission Inventory of Heavy Metals and Persistent Organic Pollutants, TNO-MEP-R 95/247, TNO, The Netherlands

• UK NAEI 1990 – 2006



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Table: 2G Leakages from Electrical Equipment and from Fragmentisers leading to POPs Emissions in the UK, 1990-2006

Table: 3B Dry Cleaning POPs Emissions in the UK, 1990-2006

Table: 3C Textiles & Dyes POPs Emissions in the UK, 1990-2006

Table: 3D Solvent manufacture (Trichloroethylene and Tetrachloroethylene) POPs Emissions in the UK, 1990 - 2006


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1.14 Fragmentisers & Shredders (2G)


Metal containing wastes such as electrical equipment, white goods and cars , are recycled by breaking down in fragmentisers and shredders. The fragmented material is separated into ferrous scrap, non-ferrous scrap and a waste fraction of the other components principally plastic fluff. PCBs may be present in the capacitors and transformers contained within old electrical equipment. There is potential for PCBs to be released to air during the fragmentiser operations and released to land from the landfilling of the waste fractions and process dusts. Increasingly efforts are made to de-pollute the material entering the shredders which should lead to an elimination or at least a reduction in the PCB entering the shredder.


Activity Data

The use of PCBs within electrical equipment has been steadily declining since the Europe wide ban of new PCB containing equipment in 1985, and the further removal of existing stock between 1996 – 2000. This means the quantities of PCBs within white goods sent for fragmentising/shredding should also continued to decline. Also the successful depolluting of equipment will lead to PCB containing material being diverted from the fragmentisers.

Emissions to Air

Accurately quantifying the emissions of PCB from fragmentising operations are difficult. Dyke (1997) quotes the figures published by Harrad et al (1994) as 240 kg (assumed to be 1993) but also states that these emissions are likely to be dropping as existing stock goes out of commission and is replaced by non-PCB units. The NAEI uses the Harrad figure scaling what would be the best assumed decline in emission across the time series following the same approach used for capacitor and transformer leaks. This reduces the emissions from 414 kg in 1990 to 16 kg in 2006.


The most likely release of PCB from fragmentiser operations is to landfill with accidental release to land expected to be limited to the sites themselves. Dyke (1997) states that the Department of Environment (1994) quoted concentrations in fragmentiser waste at 20 ppm. This was used in combination with data from the Environment Agency, which stated 800 kt of waste being committed to landfill in 1997 (350 kt from fragmentised white goods and 450 kt from fragmentised vehicles). This gave rise to approximately 16,000 kg of PCB in landfill waste. These figure have been used in the current estimates using the same downward scale used for air emissions in the NAEI. This quotes emissions as 44281 kg in 1990 and 2684 kg in 2006, noting that all quantities will be landfilled.

Releases to Water

No data are available on releases to water from fragmentising operations. If the plant use water for cleaning the scrap then this would have presented a potential release.


The use of PCBs has been banned in new electrical equipment since 1985. Therefore, the amount of PCBs in waste electrical equipment is decreasing as the old equipment is replaced. It should also be noted that figures quoted for emissions to land would be as landfill while accidental emissions to land

AEA/ED43184/Issue 2 Review and Update of the UK Source Inventories: Annex

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are expected to be limited. Both quantities are expected to continue to decrease as old units are taken out of commission.

1.14.3 Results

The graph and table of results provided in the section above on leakages from electrical equipment (also in sector 2G) includes the emission estimates from fragmentisers and shredders.


There is much uncertainty in the estimated emissions of PCBs from fragmentising operations. The Europe wide ban of new equipment in 1985 followed by further measures in 1996, means that there must be few scrap cars now older than 1986. But there has also been difficulty in identifying PCB containing equipment for smaller units, this in combination with varying waste streams make it difficult to accurately estimate PCB emissions to air from one waste batch to the next, with emissions likely to vary.

The same issues exist for emissions to land, noting that accidental releases to land will likely be extremely limited due to strict controls in place, and therefore the main transfer will be of waste materials to landfill. Very little monitoring data exists, and quantities of PCB within goods consigned to fragmentisers are likely to be estimates. As such uncertainty will be high in all figures reported here, and should only be used as a guide to emission trends and comparison to other emission sectors.

1.14.5 References

• Department of Environment (1994), Polychlorinated Biphenyls – Waste Management Paper No 6, HMSO, UK


• Environment Agency. http://www.environment-agency.gov.uk/static/documents/Business/lfill_briefing_1795441.pdf

• Harrad S J, Sewart A P, Alcock R, Boumphrey R, Burnett V, Duarte-Davidson R, Hallsall C, Sanders G, Waterhouse K, Wild S and Jones K C, (1994), Polychlorinated Biphenyls (PCBs) in the British Environment: Sinks, Sources and Temporal Trends, Environmental Pollution, 85, 131-146

• UK NAEI 1990 - 2006

1.15 Dry Cleaning

1.15.1 Sector Description (NFR Code 3B)

Some dry cleaning processes use chlorinated organic solvents (e.g. perchloroethylene) to clean clothes in a solvent bath, followed by drying in hot air. However, potential dioxin releases from the dry cleaning process are unlikely to be formed in the cleaning process itself, but are more likely to be a result of original dioxin contamination or dirt on the textiles that are being cleaned.

In the dry cleaning process the solvents tend to be regenerated leaving behind a sludge which is removed as a waste product. In addition, some waste water is generated, originating, for example, from the humidity of the clothes, and the steam from drying the sludges.


This is a sector not currently reported under the NAEI as emissions to air are unlikely. There is however potential for emission to land and water from waste sludges and water used within the process. No viable set of data for the UK over the time series has been for quantities of dry cleaning that is carried out.


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The UK inventory of dioxins to land and water (Dyke 1997) for this sector quoted an estimated activity that produced a total of 4000 tonnes of solid residues per year and 5 million litres per year of waste water in the UK. The estimated activity figures for the UK have been based on these values and scaled across the time series based on population. This is a simple method that will provide raw numbers for the sector, although uncertainty will be high and it is intended that this data act as a guide to compare against other sectors.

Emissions to Air

Emissions of POPs to air from dry cleaning are unlikely to be significant.


The UK inventory of dioxins to land and water (Dyke 1997) quotes measurements from other European countries with concentrations of dioxins in the sludge from dry cleaning of 0.17 to 2.46 mg I-TEQ/tonne. A best estimate for this inventory is assumed as the mid-point of the range as 1.32 mg I-TEQ/tonne. Note that these concentration data are very uncertain.

Releases to Water

For releases to water, only one data point is available from Sweden, which was used in the UK inventory of dioxins to land and water (Dyke 1997). The single data point is 0.018 mg I-TEQ/million litres of waste water.


The releases of dioxins to land and water from dry cleaning is likely to decrease in the longer-term because of improved environmental performance of dry cleaning machines and the reductions in dioxin contamination in textile treatment.

1.15.3 Results

The table shown at the end of chapter 2G (leakage from electrical equipment) summarises the POPs emission trends from dry cleaning operations in the UK. The trend is directly linked to population and hence is a slightly increasing trend since 1990, with emissions of dioxin to land quoted as 5.1 g I-TEQ in 1990 and 5.5 g I-TEQ in 2006. Emissions of dioxin to water remain small thorough out.


There is very limited data on dry cleaning activities in the UK which can be used to estimate waste flows. There are only limited data on dioxin concentrations in releases to land and water from such waste flows. However, the development of very approximate estimates is useful to show that releases to water are unlikely to be significant but that there is likely to be a small release to land, estimated at 5.1 g I-TEQ in 1990 and rising to 5.5 g I-TEQ in 2006. The estimated release to water is calculated as 0.00009 g I-TEQ (i.e. negligible). Although the estimated releases are very uncertain, this sector is not a priority for improvement of the inventory.

No data are available on releases of other POPs, although these are likely to be negligible or zero.

1.15.5 References


• ONS population data for UK 1990-2006


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1.16 Textiles (3C)


The textile industry uses a number of chemicals for processes such as washing, dying and treatment of textiles. Some chemicals and dyes, which have been used for coating and preservation of textiles, have the potential to be contaminated with dioxins. For example, pentachlorophenol (PCP) has been used in the past in many countries to preserve wool and the treated wool has been imported into the UK. The use of PCP in the EU has been banned.

There is potential for releases of dioxins to land and water from textile treatment processes, but minimal potential for significant releases to air. Releases to land could occur via the sludges from the treatment of waste water and other waste sludges generated in the process.


This is a sector not currently reported under the NAEI. No activity data are available for textile production in the UK. However, just as for dry cleaning it is useful to make an approximate estimate of activity so that the approximate releases of dioxins to the environment can be estimated in order to identify whether this sector is likely to be a significant source. Dyke (1997) indicated that about 1 million tonnes of textiles are produced per year in UK. A similar approach as with dry cleaning has been adopted here using population to scale activity data across the time series.

Emissions to Air

No data are available on the potential releases of POPs to air from textile treatment, although the quantities released are likely to be negligible.


The main residues are likely to occur from treatment of waste water. For most plants the waste water is likely to be treated in the municipal waste water treatment works. The releases in the sludge from these treatment works have not been estimated in this section because of a lack of data and the potential for double counting with the estimates of release in waste water below. Small amounts of some other sludges and residues are likely to be generated from the textile production process itself, and these are likely to be sent to a controlled landfill site.

Releases to Water

Estimated emission factors have been derived from the UK inventory of dioxins to water (Dyke 1997) as 0.48 µg I-TEQ per tonne of textile produced (best estimate) within a range of 0.032 to 0.93 µg I-TEQ/tonne produced.

Emissions of HCB and PCB are likely to be negligible.

Products

There is potential for dioxins to be present in small quantities in textile products that have been treated with certain specific chemicals. However, no data are available on potential concentrations.


It is likely that the chemicals that can lead to the formation of dioxins in the textile treatment process are being phased out, and the releases would be expected to be decreasing from this sector.


88 AEA

1.16.3 Results

The table shown at the end of chapter 2G (leaks from electrical equipment) summarises the POPs emission trends from the NFR 3C which includes the textile sector in the UK. The trend is linked to population and hence is a slightly increasing trend since 1990, although emissions are small for all years at around 0.50 µg I-TEQ per year.


The estimated releases of dioxins to water are very uncertain, but are useful to indicate that this sector is unlikely to have a major contribution to total releases of dioxins. The estimated release is 0.50 µg I-TEQ, within a range that demonstrates the uncertainty of 0.97 to 0.30 µg I-TEQ.

More information is needed on the activity data, the types of chemicals used at the plant, and whether waste water is discharged directly to the municipal sewer or treated before discharge leading to a sludge for disposal.

1.16.5 References


• ONS population data

1.17 Manufacture of Dyes and Inks (3C)


A wide variety of dyes, inks and coating materials are produced in various countries, some of which can be contaminated with dioxins as a result of the chemical synthesis route used. Their manufacture and use can lead to releases of dioxins into the environment, for example through waste water or residues from the production process.

It is likely that the chemicals that can lead to formation of dioxins in inks and dyes, such as dioxazine dyes that can be manufactured using chlorinated phenols and chloroanil, have been phased out in many processes.

No information has been obtained on the manufacture of these materials in the UK, although the use of such practices is likely to be small scale and will phase out towards the more recent years of the inventory. No estimates have been made.


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1.18 Composting (4D1)

1.18.1 Sector Description (NFR Code 4D1)

Improved waste management policies have resulted in the steady increase in the quantity of biodegradable waste being composted both at home and in commercial composting sites.

Due to the possible contamination of biodegradable waste with POPs there is a potential for the emission of POPs from the production and use of compost. Due to the steady increase in composting the emissions from this practice are anticipated to increase in the coming years.


The quantity of biodegradable waste composted annually has increased in recent years. No estimates were identified of the quantity of UK material composted either industrially or domestically. It has been assumed that the waste and composting activities in Ireland would be similar to the UK and data from the Irish National Waste Database have been used scaled by population.

Emissions to Air

Emissions of POPs to air from composting are not currently reported in the NAEI and are likely to be negligible.


Releases to land have been calculated based on use of the compost product. The UNEP Toolkit (2005) provides a factor of 15 µg I-TEQ/tonne dry matter. Dyke (1997) quotes a value of 11.5 µg I-TEQ/tonne (figure quoted 11.5 ng I-TEQ/kg) wet matter, based on MSW compost used for agriculture. In this case the UNEP toolkit figure has been used to best represent the activity data available. It has been accepted that as a worst case scenario all compost produced is used on land and that the weight of compost produced is equal to the weight of biodegradable waste composted. The emissions quoted show an increasing trend from 3 g I-TEQ in 1990 to 18 g I-TEQ in 2006. The 1993 emission to land quoted by Dyke (1997) of 1.7 g I-TEQ is for commercial compost to agriculture only, the current estimate of 3.44 g I-TEQ will include domestic composting as well.

Releases to Water

Releases of POPs to water via leachate from the composting process are possible, although the quantities of leachate are small and the total release of POPs via this pathway is likely to be low compared to other sources. No data are available on concentrations in leachate.

Products

The compost product is likely to contain traces of some POPs, and this is covered under releases to land through use of compost, above. Potential Future Changes

The production and use of compost is likely to increase in future and, although the overall POPs concentrations in the fraction of waste are likely to decrease, the anticipated expansion of this practice will result in a slight increase in the release of POPs to the environment.

1.18.3 Results

The graph below summarises the emission estimates to air, land and water from composting in the UK, and a table of the time series of emissions is also shown below.


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UK POPs Emissions: 4D1 Composting, 1990-2006

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

20.00

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

g IT

EQ

dio

xin

s

DIOXIN LAND

Table: 4D1 Composting Activities for POPs Emissions in the UK, 1990-2006


92 AEA


There are several uncertainties with the estimated release of dioxins to land from composting. In particular, the concentrations of dioxins in compost are uncertain and how they will change with time as atmospheric levels of dioxins have fallen significantly since the early 1990s it is likely the concentrations in UK herbage have also fallen.

The estimated concentration in the current estimates is taken from the UNEP toolkit (2005) and was 15 µg I-TEQ/tonne dry matter, based on a default emission factor. The potential for actual emissions to vary from the default quoted are high. The uncertainty in these estimates is further heightened as activity data is based on using Irish activity data scaled to UK by population reflecting the lack of UK activity data. The figures quoted by Dyke (1997) for a 1993 baseline suggest UK activity should be around 147 tonnes of wet weight compost; the current estimate for UK activity for 1993 is 229 kt (Irish activity for 1993 14.2 kt). However Dyke’s estimate was based solely on compost commercially produced for use in the agricultural sector, current estimates include domestic compost.

The difficulty in gathering such activity data reflects the diffuse nature of domestic composting. It is recommended that UK activity data be sourced and dioxin measurements to be taken from sampling of finished products.

However this inventory sector is likely to take a low priority given the small quantities released.

1.18.5 References


• EPA (2006) Waste Database Report

• http://www.epa.ie/downloads/pubs/waste/stats/epa_national_waste_report_20063.pdf


• http://www.epa.ie/downloads/pubs/waste/stats/national%20waste%20report%202005.pdf


• http://www.epa.ie/downloads/pubs/waste/stats/epa_national_waste_report_2004.pdf

• EPA (2003) Waste Database Interim Report

• http://www.epa.ie/downloads/pubs/waste/stats/epa_national_waste_interim_report_2003.pdf

• EPA (2002) Waste Database Interim Report

• http://www.epa.ie/downloads/pubs/waste/stats/epa_national_waste_interim_report_2002.pdf


• http://www.epa.ie/downloads/pubs/waste/stats/epa_national_waste_database_2001.pdf


• http://www.epa.ie/downloads/pubs/waste/stats/name,11734,en.html

• EPA (2005) - National waste report – compost facilities

• http://www.epa.ie/downloads/pubs/waste/stats/epa_composting_2005.pdf

• UK NIR (2007) - UK National Inventory Report http://www.airquality.co.uk/archive/reports/cat07/0810291043_NAEI_2006_Report_Final_Version(3).pdf



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1.19 Pesticides (4G)


This sector will cover all emissions of POPs released during the manufacture of pesticides as well as their use such as during crop spraying. While the use of HCB as a pesticide has been banned in the UK since 1975 (Environment Agency), it continues to released through the contamination of current plant protection products.


Activity Data

The emissions from the pesticide sector will occur either during production of pesticides, typically associated with dioxins and HCB, and those emissions generated during use, which will be solely HCB.

Emissions generated during production

The activity data and emission factors for dioxins in pesticide production used within the NAEI have come from one source, the HMIP report from 1995. The data in this case has been used in general fashion with emissions quoted for ‘pesticide production’, or emissions associated with production of ‘halogenated chemicals in pesticides’. These emissions have used the same figures scaled across the entire time series, assuming that production is static year on year. It is worth noting that the pesticide industry is dynamic with new products frequently coming onto the market and existing products falling out of favour.

The same report has also been used to quote emissions associated with PCP pre-treated timber, noting that this practice ceased in 1998 as a result of regulation. The NAEI reports these emissions for the earlier part of the time series again using the same method of using single values scaled across all years.

The NAEI quotes emissions for HCB from the production of Carbon Tetrachloride, Sodium Pentachlorophenoxide, and Picloram. Neither Picloram nor Pentachlorophenol have been produced in this time period.

Carbon tetrachloride was traditionally used as an intermediate primarily in fire extinguishers (HSDB and Environment Agency) but also in the metal, petrochemical and pesticide sectors. In this case it has been reported under for NFR 4G for its use as a pesticide. Carbon tetrachloride is a known Ozone depleting substance and it’s wide scale use has been banned for some years including as a pesticide. The emissions within the NAEI quote production up to 1994 based on historic emission factors from a similar era, as well as activity data from an AEA estimate. The emissions in this case are likely to have high uncertainty attached to them but only occur in the early part of the time series.

Sodium Pentachlorophenoxide is a fungicide used in the pre-treatment of timber in a similar fashion to PCP (HSDB). As with PCP it has ceased to be used in wood treatment for some years and emissions within the NAEI ceased to be reported after 1996. The emission estimate comes from an AEA estimate matched against Duiser and Veldt’s (1989) emission factors. Uncertainty is likely to be high but emissions occur only in the first half of the time series.

Emissions generated during use

The emissions of HCB from use of contaminated pesticides are based on activity data from the Pesticide Usage Survey (PUS) and against historic emission factors from Duiser and Veldt (1989). The PSU will be based on data taken from operators and is periodically updated on a three to six year cycle, which will build confidence in the data provided. The emission factors used in this case are based on values quoted by Duiser and Veldt (1989) and will unlikely reflect the contamination levels seen in more recent years of the time series. This will be because the source of HCB in this case is


94 AEA

contamination and the improvement in process control over the time series should see these contaminations drop significantly.

Even then the emission factors quoted by Duiser and Veldt seem high by other standards of the time.

Duiser and Veldt quote HCB contamination of Chlorthalonil (also known as TPN) as 0.5 kg/t of product used. Other papers quote lower values; Benazon (1999) quotes contamination levels in Canada for the 1980s and early 1990s as 0.026 kg/t or 26 ppm far below the figures quoted in Duiser and Veldt. Bailey (2001) quotes the working limits set by the US EPA as 40 ppm or 0.04 kg/t of product used. This would suggest that the emissions currently quoted by the NAEI are an over estimate. The current estimates have based the emission factors on Bailey’s value as a conservative estimate. Similarly Duiser and Veldt quote emission factors for Quintozine (also known as PCNB) as 5 kg/t of product used. Sweetman et al (2005) quote a range of figures for HCB contamination of Quintozine, but the accepted values for the early 1990s are 1 kg/t dropping to 0.5 kg/t by 2006. This range has also been accepted in the current estimates.

Duiser and Veldt quote an emission factor of 3 kg/t for Chlorthal-dimethyl (also known as TCTP), Sweetman et al (2005) again quotes a range of contamination values, which vary between 0.7 kg/t to 3 kg/t. In this case the emission factor used will remain unchanged. The sheer variation in emission factors quoted illustrates that uncertainty in the known concentrations of HCB in working pesticides, other than to state that likely contamination is decreasing.

These emissions will also assume that all of the HCB contamination within the pesticide used is volatised and will be counted as emissions to air only, this is unlikely to be the case. Further work carried out by AEA has looked to add greater understanding to crop spraying and emissions, where previously all emissions were calculated as being to air. The paper ‘Review and update of HCB inventory emission to air, land and Water, Yongfu Xu, 2008, calculates the split of emission to air, soil and water to be 70.2% (air), 28.8% (soil) and 1% (water). The data currently presented within the NAEI has been redistributed using this method.

A full table of references for activity data and emission factors for air is shown in Table 1.22 on the next page.


AEA 95

Table 1.21 Reference Sources used within the inventory for 4G Pesticide Production and Use

NFR 4G Pesticide Production and

Use Activity Emission factor Dioxins Activity Code Source Name

Process emissions Production of Halogenated chemicals for pesticides



Process emissions Production of Pesticides HMIP, A Review of Dioxin Emissions in the UK, Report No HMIP/CPR2/41/1/38, October 1995


PCP treatment of wood

Preservation of wood by impregnation

HMIP, A Review of Dioxin Emissions in the UK, Report No HMIP/CPR2/41/1/38, October 1995 - used up to 1998 assumed to be '0' thereafter


HCB

Process emissions Production of Carbon tetrachloride

AEA estimate prior to 1993, assumed '0' from 1994 and thereafter

Figures to 1996 from Duiser et al, 1989 but the source of subsequent factors is unknown.

Process emissions Production of sodium pentachlorophenoxide

AEA Estimate Duiser, J.A., Veldt C. 1989, Emissions to the Atmosphere of PAH, PCN, PCB, Lindane and HCB in Europe, TNO Report 89-036 Apeldoorn The Netherlands.

Process emissions Production of Picloram Pesticide Survey data. 1994 Duiser, J.A., Veldt C. 1989, Emissions to the Atmosphere of PAH, PCH, PCB, Lindane and HCB in Europe, TNO Report 89-036 Apeldoorn The Netherlands.

Solvent emissions while in use

Chlorothalonil use Pesticide Usage Survey data. See reference : http://www.csl.gov.uk/aboutCsl/scienceGroupsAndTeams/fsg/pesticides/pusTeam.cfm

Duiser, J.A., Veldt C. 1989, Emissions to the Atmosphere of PAH, PCH, PCB, Lindane and HCB in Europe, TNO Report 89-036 Apeldoorn The Netherlands.


chlorthal-dimethyl use Pesticide Usage Survey data. See reference : http://www.csl.gov.uk/aboutCsl/scienceGroupsAndTeams/fsg/pesticides/pusTeam.cfm



Quintozene Pesticide Usage Survey data. See reference : http://www.csl.gov.uk/aboutCsl/scienceGroupsAndTeams/fsg/pesticides/pusTeam.cfm



96 AEA

Emissions to Air The dioxin emissions to air are low at 0.4 g I-TEQ in 1990 and fall significantly after the banning of the use of PCP for pre-treatment of timber. 2006 emissions are quoted as 0.02 g I-TEQ. These emissions are based on using the same activity and emission factor values scaled across all years for the manufacture of chlorine based pesticides. The uncertainty in these values is high, but the emissions are likely to be low within the context of the inventory.

Aside from the production of carbon tetrachloride, which ceased production in 1993, the emission of HCB is dominated by the use of contaminated pesticides. The figures currently quoted within the NAEI however are likely to be an over estimate and have been recalculated based on a range of values quoted by Bailey, and Sweetman, who reviewed available HCB concentrations in pesticides in 2005. The NAEI HCB emission to air quoted for 2005 is 810 kg. Based on the new emission factors selected the total emission of HCB is 88 Kg, which will be split between air, land and water, using Yongfu Xu’s method.

The most significant issue is the steady rise in the release of HCB since 2002 which reflects the increased use of chlorthalonil from 500 tonnes per annum in 2002 to around 1500 tonnes per annum in 2006. This was supported by the trend (Becker at al, 2009) in measured HCB concentrations in the Canadian Arctic. The current estimates quote a HCB emission to air in 2002 of 29 kg and in 2006 of 60 kg. After the use of Hexachloroethane (HCE) ceased in the UK around 1998 the emission of HCB from pesticide production and use has remained the single largest source of HCB in the UK.


The original estimates within the NAEI assume all HCB from crop spraying is volatised and released to the environment as air emissions, this is unlikely to be the case. Yongfu Xu (2008) developed an approach to estimate the split between air, land and water. This assumes that 70.2% of the HCB emitted is volatised to air with the bulk of the remainder (1% goes to water) going to soil. This method provides emissions to soil in 1990 as 54 kg, which declines up to 2000 reaching a low of 12 kg in 2001 before increasing again, as with air, to 25 kg in 2006.

Releases to Water

The emission to water from crop spraying is likely to be minimal as the direct ingress of pesticide to water is likely to be minimal. Both as matter of crop spraying practices and occurrence of waterways near treated land. The emissions of HCB quoted in the current estimates vary from 1.9 kg in 1990 to 0.9 kg in 2006.


The pesticide industry is dynamic with new products frequently reaching the market as others fall out of favour. Further more the usage trends of existing pesticide can change quickly, which reflects how the pesticide industry deals with the dynamic nature of the agricultural environment. In recent years the use of chlorthalonil has become increasingly popular, and while the levels of contamination are likely to be decreasing, this increase in use has suggested that an emission in HCB has increased.

1.19.3 Results

The graph below summarises the emission estimates to air, land and water from pesticide use in the UK, and a table of the time series of emissions is also shown.


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UK POPs Emissions: 4G Pesticides, 1990-2006

0.00

100.00

200.00

300.00

400.00

500.00

600.00

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

g IT

EQ

dio

xin

s a

nd

Kg

HC

B

HCB AIR HCB LAND HCB WATER DIOXIN AIR

Table: 4G Pesticide Production and Usage for POPs Emissions in the UK, 1990-2006


AEA 99


While activity data for pesticide usage is surveyed regularly, the level of contamination within pesticides is reported rarely. The estimates currently reported within the NAEI are based on values taken from Duiser and Veldt (1989) and quote contamination levels for Chlorthalonil as 0.5 kg/t used, Quintozene as 5 kg/t used and Chlorthal Dimethyl as 3 kg/t. The review by Sweetman (2005) suggests that the emission factors currently quoted in the NAEI may be an over estimate and the uncertainty in the levels of contamination are high. The figures quoted by Bailey and Benazon relate to North American estimates, and a lack of UK measurements exists for contamination of HCB in pesticides. Although all sources are in agreement that contamination levels are likely to decrease across the time series as process production improves.

Estimates have also been made within the current projections for HCB emission to land and water based on the paper by Yongfu Xu (2008). While this redistribution of the emissions currently quoted by the NAEI shows an improvement, the figures quoted still have the potential to have a high level of uncertainty, and are secondary to measured values.

One area for concern is the suggested increasing emissions of HCB to air and land as a result of increasing quantities of chlorthalonil being used within the UK.

The pesticide sector remains the key source of HCB emissions for the UK inventory. Hence it is recommended that measurements be undertaken of the current contamination levels within pesticides currently in use as a priority.

1.19.5 References

• Bailey RE (2001) Global HCB emission, published in Chemosphere 43, pp 167 – 182

• Becker at al (2009) ‘Changing sources and environmental factors reduce the rates of decline of organochlorine pesticides in the artic atmosphere’. Journal submission to Atmospheric Chemistry and Physics by Becker et al Lancaster Environment Centre.

• Benazon N (1999) ‘HCB emissions for Ontario 1988, 1998 and 2000’, Draft report for Environment Canada

• Duiser, J.A., Veldt C. 1989, Emissions to the Atmosphere of PAH, PCH, PCB, Lindane and HCB in Europe, TNO Report 89-036 Apeldoorn The Netherlands.

• Environment Agency, Carbon Tetrachloride, http://www.environment-agency.gov.uk/business/topics/pollution/34.aspx

• Environment Agency. HCB, http://www.environment-agency.gov.uk/business/topics/pollution/162.aspx


• HSDB (Hazardous Substances DataBase)

• Pesticide Usage Survey data. See reference : http://www.csl.gov.uk/science/organ/pvm/puskm/pusg.cfm or http://pusstats.csl.gov.uk/myindex.cfm

• Sweetman et al (2005) ‘HCB, sources, Environmental Fate and Risk Characterisation’ Science dossier published in co-ordination with EuroChlor.

• Thistlethwaite et al (2008) ‘Inventories of Persistent Organic Pollution in Ireland 1990, 1995 and 2006’, published by AEA for the Ireland EPA.

• UK NAEI 1990 – 2006

• Yongfu Xu (2008) ‘Review and update of the HCB inventory emissions to air, land and water, paper published by AEA.


100 AEA

1.20 Landfill Waste activities (6A)

1.20.1 Sector Description (NFR Code 6A)

POPs are present in municipal solid waste (MSW) in low quantities, however due to the significantly large quantities of MSW disposed of in landfills this waste has the potential to be a significant transfer of POPs. POPs may be released from inadvertent release of landfill gas or leachate to the wider environment however these release are difficult to quantify.

In terms of inventory compilation this can be a difficult sector to ratify as the landfill gases emitted do not reflect the composition of the waste disposed of in the current year. This sector of the inventory will cover emissions from landfill activities include landfill gas management such as flaring. This sector does not include the following, incineration of MSW and ash from incinerators are covered in section (6C), composting is covered in section 4D1, and sewage sludge spreading will be covered in section 6B.


The emission of POPs from landfill activities in the current estimates come from two sources, namely emission of waste gas (methane) which is reported in the NAEI, and contaminated MSW waste load consigned to landfill, which is not reported in the NAEI. The activity data used within the NAEI is based largely on the HMIP (1995) report and updated by the Land Quality Management (2003) data (see reference in Table 1.23 shown below).

In this case there is a high level of uncertainty in both the emission factors and the activity for flared methane. The generation of waste gases in landfill are the result of waste matter decaying, with the nature and level of contamination varying from site to site. There is also an issue that the dioxin and PCB content of MSW is expected to decrease as quantities within the environment also decrease. However there may be a time –lag as to when this effect is witnessed in gas emissions.

The only credible means of gauging true emissions levels for year on year data will come from regular monitoring of gas emissions from waste. This being noted, the emission factors from the HMIP (1995) report have been used in lieu of better data, further noting that the estimates should be treated with caution and as a guide to true emissions.

A full table of references for activity data and emission factors to air for the NAEI is quoted in the table shown below.

Emissions to Air

The most likely source of emissions to air will come from escaping gas (methane) both as quantities flared and quantities not flared. The emission factors used by the NAEI (and taken from the HMIP report) are 0.95 ng I-TEQ/t for non-flared gas, and 0.0139 ng I-TEQ/t for flared gas. Using the activity data and emission factors quoted within the NAEI, emissions to air from this sector are small with 1990 emissions quoted as 2.58 g I-TEQ (dominated by non-flared gas) down to 2006 1.01 g I-TEQ.

Equally PCB emissions from this sector are also small with an emission factor of 798.5 mg/t of escaping gas, and emissions of 1.89 kg in 1990 down to 0.74 kg in 2006.


Dyke (1997) quotes dioxin concentrations as 6.3 µg I-TEQ/tonne of MSW and PCB concentrations as 24 – 52 µg /kg of MSW (52 µg kg adopted in the current estimates) as dry weight. The concentrations in current MSW are possibly lower. There have also been changes in the quantities and types of waste sent to landfill with both recycling, composting and incineration becoming much more prevalent. However 18 – 20 Mt of MSW is sent to landfill each year (Defra). The activity data used to calculate emissions to landfill have come from Defra based on MSW generation per head of population and percentages of total waste consigned to landfill. The emissions range from a high of 147 g I-TEQ in 2000 to a low of 113 g I-TEQ in 2006 for dioxin, and a high of 1194 kg in 2002 and to a low of 940 kg in 2006 for PCB.


AEA 101

Table 1.22 Reference Sources used within the inventory for 6A Landfill Activities

Releases to Water

There is a potential within the landfill environment for the generation of POPs contaminated leachate. However the quantities and nature will vary from site to site, noting that older landfill sites based on clay liners will have been replaced with more modern sites utilising better leachate control and reduction. The releases to groundwater of POPs in leachate are unknown likely to be small and have not been calculated within the current estimates.


In principle the emissions of POPs from the landfilling of MSW should decrease each year in the longer term due to the following reasons:

• Reduction in overall loading of POPs to the environment and hence the quantity of POPs disposed to landfill within the MSW

• Application of improved waste management should reduce the quantity of waste landfilled

• The application of the EU Landfill Directive (1991/31/EC) and the National Biodegradable Waste Strategy should reduce the quantity of biodegradable waste landfilled (landfill gas and leachate generating) therefore reducing the emission mechanisms for the release of POPs

• Phasing out of old landfill sites for new landfills with lining and leachate collection and treatment systems

1.20.3 Results

The graph below summarises the emission estimates to air, land and water from landfills in the UK, and a table of the time series of emissions is also shown below. These data include emissions from MSW disposals to landfill as well as emissions derived from landfill gas flaring and venting.


102 AEA

UK POPs Emissions: 6A Landfill, 1990-2006

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

160.00

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

g IT

EQ

dio

xin

s, g

WH

O

TE

Q D

iox

in L

ike

PC

B

0.000

200.000

400.000

600.000

800.000

1000.000

1200.000

1400.000

kg

PC

Bs

DIOXIN AIR DIOXIN LAND DL PCB AIR PCB AIR PCB LAND

Table: 6A Landfill Activities for POPs Emissions in the UK, 1990-2006


AEA


There is a high level of uncertainty with all data used within this sector, with the activity data for escaping gas having the highest certainty. The emission factors used for escaping gas have been based on the HMIP (1995) report, noting that POPs emissions from modern landfills may not be correctly represented by the emission factors used in this report and recent measurements have not be identified.

As the generation of gas from site to site will vary, as will the level of contamination in waste gas (methane) it is extremely difficult to assign one emission factor to all sites with any level of confidence. It is likely that the aggregated activity values for total gas generation in the UK will have a range of POPs concentrations.

The estimates made for dioxin concentrations in MSW consigned to landfill are based on the emission factor quoted by Dyke in 1997 (6.3 µg I-TEQ/tonne of MSW for dioxin and 24 – 52 µg /kg of MSW for PCB) noting that concentrations are expected to decrease as the quantities of dioxin and PCB in the environment decrease. The activity data in this case has been based on calculations made by Defra for quantities of waste generated per person and percentage of waste landfilled.

Recommendations for improvements in this sector will include POPs sampling of MSW and MSW leachate, as well as monitoring concentrations in landfill gas streams. It should be noted that emissions from this sector are likely to be small by comparison to other sectors and improvement of this sector may take a lower priority.

1.20.5 References

• Defra Waste stats: http://www.defra.gov.uk/environment/statistics/waste/wrindustry.htm




• Land Quality Management Ltd, Methane Emissions from Landfill Sites in the UK, Reference No LQM Report 443/1, January 2003

• UK NAEI 1990 - 2006


105 AEA

1.21 Waste Water and Sewage Sludge (6B)

1.21.1 Sector Description (NFR Code 6B)

Dioxin concentrations have been measured in low concentrations in municipal waste water. During treatment at municipal waste water treatment works (WWTW) these pollutants are concentrated in the sewage sludge generated. Various disposal routes exist for sewage sludge including land spreading on agricultural land, composting, disposal at landfill, and in the past, disposal at sea.

In terms of releases to water, the effluent from WWTW are likely to contain trace concentrations of some POPs which discharge directly to water bodies.


The chief emissions of POPs will be to land and water through the disposal of sewage sludge generated during dewatering processes, and the emission of treated water, which still contains levels of POPs. The current estimates will relate solely to waste water from water treatment works. The emission of dioxin to water from storm drains as a result of surface runoff on roads has not been calculated, although it is suspected that this may be a source of dioxin. However the overloading this can cause at WWTW make lead to discharge of untreated sewage removing the abatement effect of the works.

The NAEI reports emissions of PCB to air from the spreading of sewage sludge to agricultural land. Waste water has the potential to contain low levels of POPs, which are then concentrated during the dewatering process. These then have the capability of being released to air during spreading. The disposal of sewage sludge by dumping at sea and consignment to landfill are discussed later in the chapter, but the spraying element of use of agricultural land is believed to help increase surface area and the ability of PCB to released to air.

The NAEI activity data is based on Defra survey data for quantities used within agriculture; this is combined with emission factors from Dyke and Harrad (1993). The concentration of POPs in biological materials and food chains is expected to decline across the time series as quantities in the environment decrease and tighter legislation controls contamination in foodstuffs. The factors quoted by Dyke and Harrad have been adjusted to decline across the time series to capture this effect. A table of references used by the NAEI is shown below.

Table 1.23 Reference Sources used within the inventory for 6B Waste Water and Sewage Sludge

Emissions to Air

The NAEI currently quotes the emission of PCBs to air from sewage sludge spreading on agricultural land, given the similar if less volatile nature of dioxins it is possible to suggest that dioxin emissions may also be likely from this source, but emission factors have not been found to substantiate this.

The emissions quoted in the current estimates and also the NAEI are 71 kg of PCB in 1990, which then decline to 11.50 kg in 2006. This decline occurs while activity data remains at a roughly constant level, and is due to a reduction in the emission factor, which was made on the assumption that PCB concentrations should be declining over the time series.


Review and Update of the UK Source Inventories: Annex AEA/ED43184/Issue 2

106 AEA

The UNEP toolkit quotes emission factors for sewage sludge as emission to land, these equate to 100 µg -ITEQ/t of sewage (as dry weight) for urban areas where industrial waste flows are not included. This can be used against the activity data provided by Defra for quantities of sludge used in agriculture.

At the same time it has been possible to use data from the Ireland POPs inventory to scale up quantities consigned to landfill based on the Defra data. This assumes that similar proportions and practices exist in the UK and Ireland, which may not be correct.

Sweetman (2005) quotes emission factors for PCB content of sewage sludge noting that the concentrations vary significantly; a range is quoted of 110 – 440 µg /kg of sewage (dry weight)). Another issue is regarding the sampling of sewage for PCB concentrations, this is because sampling work is based on looking for individual PCB congeners and the congeners measured vary between references. The values provided by Sweetman are based on a set of 37 congeners (noting that 209 PCB congeners exist), with the worst-case scenario (440 µg /kg of sewage) used for the current estimates. The same emission factor has also been used to gauge emissions of PCB to landfill in sewage.

Dioxin emissions for sewage sludge spreading remain fairly constant at around 50 g I-TEQ per annum, emissions to land for landfill are lower with emissions of 10.9 g I-TEQ in 1990 falling to 5.1 g I-TEQ in 2006. Similar is true of the PCBs, with sewage sludge spreading emissions around the 220 kg mark for all years, and landfill quantities are lower at 48 kg in 1990 dropping to 23 kg in 2006.

Releases to Water

POPs releases to water from waste handling are seen as potentially the key water emission source. As such each POP will be discussed individually here. Dioxins

The current estimates have used two methods as means of comparison to gauge uncertainty within the data. The first approach uses data provided by the Pollution Inventory, who sample for different POPs periodically, in the case of dioxin in 2006. The method used involved a small monitoring set of data which was then scaled to the rest of the UK based on waste waters received, and quotes the 2006 emission to water as 25.62 g I-WHO TEQ. Using population to derive an emission factor of 24.12 ng WHO TEQ/per person, it has been possible to scale data for all years of the time series.

A second approach involves using data taken from WRc report (2008). This approach takes the UNEP default for sewage sludge 100 µg I-TEQ/t of dry matter, and then based on the physical properties of dioxins (water/solid portioning based on Log Octanol equilibrium) to calculate the likely concentration in effluent waters (2 ng I-TEQ/m

3) and then uses this against the volume of waste waters received for

2006/07 (based on OFWAT data) to gauge a total emission of 7.5 g I-TEQ. Again using population for 2006 it is possible to derive an emission factor of 123 ng I-TEQ/ per person and scale emissions across all years. This approach was taken, as a full set of waste water activity data for the time series was not found, with only incomplete data available.

The range in the values produced shows the level of uncertainty in gauging dioxin concentrations, noting also the discrepancy between units, where WHO TEQ is likely to be marginally higher than I-TEQ, although in this case with the level of uncertainty seen this difference is likely to be negligible.

Given that the Pollution Inventory approach is more closely tied to UK specific emissions it has been accepted for the current estimates, assuming that I-TEQ emissions will equal WHO –TEQ.

If population has been used as an activity driver there is a slight increase in emissions. It is expected that concentrations in the food chain would decrease over time as concentrations in the environment decrease, this effect however may be off-set by the increase in population causing emissions to stay at roughly the same level. Based on the PI approach emissions in 1990 are quoted as 24.1 g –WHO-TEQ and in 2006 25.62 G-WHO-TEQ.

HCB

As with dioxins the Pollution Inventory also records data for HCB emissions in waste waters, this was based on a sampling set for 2002. Emissions for HCB in 2002 were quoted as 1.30 kg. Using population data it has been possible to derive an emission factor of 21.95 µg /per person and then scale this across all years of the time series. This gives a slowly increasing HCB emission of 1.26 kg in 1990 and 1.34 kg in 2006.


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PCB

The emission of PCB to air and land are likely to make up the key routes of emission, however formerly the practice of dumping sewage sludge at sea was used until 1999 as an alternative to agricultural spreading, landfill or incineration particularly for urban sludges which would tend to have higher POPs concentrations. While this practice was banned in 1999 it has been worthwhile to calculate emissions prior to this data.

Data from the Ireland POPs inventory was used to scale up UK agricultural sewage spreading data to estimate quantities dumped at sea from the UK assuming that similar practices occurred in the UK for the early part of the time series. This activity data was then used against the emission factors quoted by Sweetman (2005) for sewage sludge in agricultural spreading. This resulted in emissions of 83.1 kg of PCB in 1990 and 82.6 kg of PCB in 1999, when the practice was banned. As with other emissions estimates in this sector these emissions will have a high level of uncertainty attached to them.


The uncertainties within the current sector are particularly high making predictions of potential future trends difficult. However as POPs concentrations in the environment decrease it is logical to assume that concentrations in foodstuff and in kind waste waters will also decline over time. No indication can be given on rate of decline.

1.21.3 Results

The graph on the next page summarises the emission estimates to air, land and water from waste water treatment and sewage sludge disposal in the UK, a table of the time-series of emissions is also shown.


This is due to the difficulty in quantifying POPs mass inputs into WWTW will vary depending on the types of industrial sources impacting on the concentrations and the balance between industrial and domestic sources.

As a means of comparison two methods have been used to calculate the emission of dioxins to water from effluent streams, which in turn have help gauge the overall uncertainty in the sector. These quotes based on 2006 are 7.5 g I-TEQ and 25.62 g WHO-TEQ. Noting the discrepancy in units, and putting this to one side, the range of values quoted is not surprising.

The waste water sector is the key sector for emissions to water for all POPs included in the current inventory and is of high priority for review and improvement. The recommendations for improvement include further analysis of sewage sludge, as a means of updating the current emission factor estimates.

1.21.5 Dredging (6B)

The current estimates quoted above for NFR 6B have excluded one possible source of POPs to the aquatic environment. Dredging of rivers, estuaries, harbours, etc. is carried out to provide channels for navigation and for flood control. The dredged materials that are removed are disposed at sea or deposited on land, or in the case of aggregate dredging potentially recycled into other industries such as the manufacture of pre-cast concrete and construction. Sediments of watercourses can contain high quantities of POPs, for example down stream of industrial sources.

This activity can lead to the enhanced availability of POPs especially in the water column. This is a transfer of POPs within the environment and so has not been included in the current inventory.

However given the large quantity of material moved and the enhanced concentrations in sediment compared to soils or other natural background materials the quantities re-mobilised may be significant. Dyke in 1997 made an estimate of dredging to land as 1 Mt per year, leading to a dioxin movement of 29 g I-TEQ per year.


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1.21.6 References

• Defra Waste Stats for sewage sludge : http://www.defra.gov.uk/environment/statistics/waste/wrsewage.htm



• Gardner et al (WRc Report) (2008) ‘Sources and emission of persistent chlorinated pollutants to the water environment’, report commissioned by AEA.

• Pollution Inventory data taken from Pollution Inventory of England and Wales, Scottish Pollution Release Inventory and Inventory of Sources and Releases (Northern Ireland).

• Sweetman (2005) PCBs, fate and behaviour during wastewater treatment process, published by Lancaster University

• Thistlethwaite et al (2008) ‘Inventories of Persistent Organic Pollution in Ireland 1990, 1995 and 2006’, published by AEA for the Ireland EPA.

• UK NAEI 1990 – 2006



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Table: 6B Waste Water and Sewage Sludge POPs Emissions in the UK, 1990-2006

UK POPs Emissions: 6B Waste Water & Sewage Sludge, 1990-2006

0.00

50.00

100.00

150.00

200.00

250.00

300.00

350.00

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

g IT

EQ

dio

xin

s

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

Kg

s o

f P

CB

an

d H

CB

, g

WH

O T

EQ

Dio

xin

Lik

e

PC

B

DIOXIN LAND DIOXIN WATER PCB LAND PCB WATER PCB AIR

HCB WATER DL PCB AIR DL PCB LAND DL PCB WATER


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1.22 Incineration (6C)


NFR 6C – Incineration will cover a wide range of incineration practices from the destruction of hazardous wastes and clinical wastes, to MSW incineration (but not electricity generation) and crematoria. Each of these practices will be dealt with separately. Tables of results and a graph for the emission of POPs to air, land and water are given at the end of the chapter. A full table of references for activity data and emission factors to air used within the NAEI is shown below.

Table 1.24 Reference Sources used within the inventory for 6C Incineration


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Continued


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Incineration: MSW Sector Description (NFR Code 6C)

The incineration of Municipal Solid Waste (MSW) provides something of a quirk within the inventory compilation. Under the guidelines used to compile these inventories any combustion of fuel for the purpose of power generation warrants the plant in question be classified as NFR 1A1a power production. This is true even if the fuel in question is MSW, this can cause confusion.

Historically waste incinerator plants were used to reduce the volume of waste with on some plant heat recovery. Tightening regulations on waste plants meant that for economic reasons since 1997 electricity generation has been built into all current MSW combustion plant. This means that emissions from MSW incineration (NFR 6C).


The combustion of MSW generates dioxins, PCBs and HCB noting that the nature of the material burnt, the method of combustion and the abatement will affect the releases and the distribution between the atmosphere, solid residues and liquid effluents. In each case the activity data used was taken from DTI stats for MSW combustion and then derived for NFR 6C, based on a split between what would constitute NFR 1A1a and what would constitute 6C. Dioxin emissions in this case have been based on the pollution inventory, which will give absolute figures. This assumes that the activity data generated has been used to derive emission factors as an intermediate and provide a full set of data, activity, emission factor, and emission.

The emission factors for PCBs and HCB have been based on literature values centred around Dyke (1997) and Van der Most (1992). As with other sectors these factors may no longer reflect current technologies and a review of potential new emission factors has been carried out. To these ends a review of current emission factors against standard defaults such as the UNECE guide book and BREF notes have been carried out and are discussed in more detail below.

Emissions to air: Dioxins The emission of dioxins to air from MSW are based on the Pollution Inventory and then using DTI activity data to derive emission factors. The UNEP toolkit (2005) quotes emission factors for dioxin as between 3500 and 0.5 g I-TEQ/Mt dependant on abatement. The emission factors derived within the NAEI range from 207.5 g I-TEQ/Mt in 1990 to 18.73 g I-TEQ/Mt in 1996. Placing the early emission factors between UNEP class 2 and 3, which are minimal abatement and fair abatement respectively. The 1996 emission factor falls between UNEP class 3 and 4, for fair abatement and state of the art abatement. As a further means of comparison the BREF note (2006) for MSW quotes an emission factor of 0.48 g I-TEQ/Mt, which will be around the UNEP Class 4 mark, and is based on a modern plant in Germany.

Emissions quoted range from 455 g I-TEQ in 1990 down to 25.10 g I-TEQ in 1996, after which the emissions will be reallocated to NFR 1A1a. The combustion of MSW counts as the single largest emission of dioxins to air anywhere within the inventory, with the improvements in plant performance cutting the emissions drastically.


The NAEI emission estimates use the same emission factor quoted by Van der Most (1992); emission factors for HCB of 0.5 g/t of MSW incinerated, to be applied to all waste types including hazardous and clinical waste. This is unlikely to give a true reflection of MSW waste streams. As a means of comparison the UNECE guidebook quotes several additional emission factors, Berdowski (1997), based on a piece of European work, quotes 0.002 g/t, Cohen (1995), a North American study, quotes 0.01 g/t of MSW. The UNECE guidebook default factor is 0.001 g/t of MSW. All three emission factors suggest the Van der Most emission factor may be an over estimate for MSW incineration, although the uncertainties will be large regardless.

The current estimates base emissions on the emission factor quoted by Berdowski (0.002 g/t) given that it relates to European plants, and will reduce the NAEI estimates currently quoted. The NAEI emission of HCB to air for this sector are low with 1.1 kg quoted for 1990 decreasing to 0.67 kg by 1996. The new estimates reduce this total further suggesting HCB emissions will be negligible.


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The PCB emissions to air have been based on activity data from the DTI and emission factors from Dyke (1997) adjusted for likely changes in abatement; 4 kg/Mt for 1990 and decreasing over time to 2.69 kg/Mt by 1996. Comparison of Dyke’s emission factors to other sources finds that they fit reasonably within a range of literature emission factors. The table shown below is based on emission factors quoted within the UNECE guidebook and the BREF note on waste incineration. The notable exception being the emission factor quoted within the BREF note for municipal waste incineration. The BREF note quoted looks to be based on more recent data noting that excluding the emission factor quoted for CIS countries, all other reference sources pre-date 2000. Significant improvements have been made in this sector over the time series quoted, in particular the way waste is segregated, with increasing activity for recycling, and the pre-treatment of wastes to minimise hazardous content.

Table 1.25 Emission factor references for PCB emissions in Municipal Solid Waste Incinerator

Reference Emission factor Kg/Mt

Reference Source

Dyke/NAEI 4 (1990) 2.69 (1996) NAEI 1990 – 1996

BREF NOTE 0.0002 – 0.0004 Based on German data 2003

UNECE 1.65 – 5.3 Czech Republic – 1995

UNECE 0.82 Europe – 1995

UNECE 2.7 USA inventory data 1990 – 1998

UNECE 1.8 – 62 USA Inventory data 1987

UNECE 10.4 – 18.5 Japan – 1999

UNECE 5 CIS Countries (formerly part of Russia) 2002

* Largely based on Table 8.4 of the UNECE guidebook on PCB emissions.

Residues / Releases to land The chief source of emissions for release to land will be through the generation of Ash. The same approach has been adopted to estimate dioxin concentrations in ash as was used for MSW in sector 1A1a power generation. Ash estimates for fly ash and bottom ash (both quantities generated and dioxin concentration) are given in the Environment Agency report, 'Solid Residues from municipal waste incinerators in England Wales’. Based on these figures the dioxin concentration of ash consigned to landfill will be 311 g I-TEQ in 1990, decreasing to 190 g I-TEQ in 1996.

A review of PCB emission factors for ash concentration has also been conducted with very few results found. Dyke’s (1997) report states that PCB concentrations in ash were expected to be below 1 µg/kg of waste burnt based on monitoring of 7 congeners. The emission of PCB to landfill has not been calculated in the current estimates but is expected to be small.

Releases to Water Emission of POPs to water would only occur where wet abatement processes have been put in place. It is believed that the majority of UK waste plants will use dry abatement processes. In the cases where wet abatement has been used any waste water generated will be passed to waste water treatment works before release. Emissions in this case are expected to be low and have not been calculated in the current estimates.


The manor in which these inventories have been compiled means that post 1996, all emissions will be reallocated to the power generation sector (1A1a). However as a guide, emissions from this sector would be expected to decline due to a variety of reasons such as increasing recycling practices which


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would reduce the quantity of plastic in municipal waste flows, also through improving waste abatement and process management at plants.

1.22.3 Results

A graph summarising the emission estimates to air, land and water from waste incineration in the UK and a table of the time-series of emissions are shown at the end of the chapter.


The greatest uncertainty will exist with the estimates of dioxins to land from ash. The nature of waste streams means that dioxin concentrations will likely vary from batch to batch. The Environment Agency paper quotes a range of emission factors for fly ash and bottom ash, the worst case scenario being adopted within the current estimates. Estimates have also been made on quantities consigned to landfill and quantities sent to other industries. This has assumed an equal split for ash generated when in reality fly ash is less likely to be used in other industries.

The data used for the generation of POPs emissions to air has greater certainty, particularly, with regard to the activity data. Recommendations for this sector will not be applicable as current and future emissions will now be recorded under NFR 1A1a for power production, and figures quoted in the current estimates will be for historic values where it is difficult to improve further on the figures quoted.

Incineration: Hazardous Waste Sector Description (NFR Code 6C) The Hazardous waste incineration sector will cover the destruction of chemical wastes at both merchant and on-site plant by incineration and thermal oxidation. While the emission of POPs from this sector depend on measurement given the lack of comparability between input streams at different plant. Where chlorinated wastes are burnt the potential for POPs generation will be greater than other non-chlorinated hazardous wastes and clearly where PCB containing components are destroyed there is the potential for releases during handling, storage and destruction.


The current estimates within the NAEI are based on the estimates for activity (as Mt of industrial wastes destroyed) within the HMIP (1995) report, against emission factors, from the Pollution Inventory for dioxins, from Dyke (1997) for PCB, and from Van der Most (1992) for HCB. Since the start of the time series in 1990 the regulations surrounding hazardous waste, or what was once termed ‘special waste’, have changed. The diverse nature of such waste makes it difficult to disaggregate quantities into the waste types, and the NAEI simply refers to them as ‘industrial wastes’. This means it is not possible to successfully quantify the levels of highly chlorinated waste destroyed.

While a lack of reference material exists to give a full review of the emission factors in use, it is possible to use standard reference materials such as the UNEP toolkit (2005) and UNECE guidebook as means of gauging the full extent of uncertainty and references used.

One issue to note is that the tightening of EU and UK regulations regarding the way wastes are managed and disposed in recent times means that the emissions from modern plants will be significantly lower than at the early part of the time series.

Emissions to air: Dioxins The emission of dioxins to air has been based on data from the pollution inventories from which emission factors have been derived using the activity data from HMIP (1995). While the Pollution Inventory identifies the merchant plant the IPPC reporting format combines the on-site incinerators with other process emissions. The on-site incinerators handle waste streams from specific processes.

The emission factors in this case have been derived of the two component parts and can act as a measure of likely of how well they match. The NAEI quotes emission factors of 17.5 g I-TEQ/Mt of waste in 1990, decreasing to 1.286 g I-TEQ/Mt in 2006. The UNEP Toolkit (2005) quotes values


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between 35,000 g I-TEQ/Mt (class 1 poorest abatement control) and 0.75 g I-TEQ/Mt (class 4 state of the art facility), with most European plants expected to fall between class 1 and class 3 (10 g I-TEQ/Mt). The BREF note for incineration quotes a working range of 10 – 10,000 g I-TEQ/Mt. These large ranges reflect the impact that the nature of the waste stream can have on dioxin emissions. While chlorinated wastes are likely to only make up a small proportion of the total waste handled their impact may be significant. Within the current estimates it has not been possible to disaggregate data and the emissions quoted are assumed to include all hazardous waste streams.

The current estimates are likely to have a high level of uncertainty with particular regard to completeness of data, disaggregation of waste streams, and abatement levels of plants, particularly at the earlier part of the time series where emissions may have been higher than quoted.

The current estimates show a decline from 5 g I-TEQ in 1990 down to 0.37 g I-TEQ in 2006.


The emissions for HCB to air have within the NAEI have been based on estimates of activity in the HMIP (1995) report scaled to all years against the emission factor from Van der Most (1992) of 0.5 kg/Mt of waste burned which has been used against all waste types including municipal wastes. This suggests large uncertainty in for both activity and emission factor in the absence of reported emission measurements from UK plant.

This has been compared against the UNECE guidebook, which gives bespoke values for high chlorine based hazardous waste (0.005 – 0.008 kg/Mt) including incineration of PVC wastes as 0.005 kg/Mt. Emission factors for hazardous wastes generally are also quoted (0.00001 kg/Mt). These figures suggest that the Van der Most (1992) emission factor may be an over estimate.

Within the NAEI estimates emissions of HCB to air remain roughly static for the time series at around 140 – 150g per year. Adopting the UNECE emission factor for PVC waste as a worst case scenario, the current estimates are around 1.5g per year.


The emissions for PCB are based on estimates of activity data from the HMIP (1995) report scaled to all years with emission factors taken from Dyke (1997) but scaled down from .83 kg/Mt of waste in 1990 to 1.22 kg/Mt in 2006. Comparison to other reference sources has proved difficult, as an example the UNECE guidebook quotes the same emission factor, 5 kg/Mt, for municipal, hazardous and sewage sludge incineration based on a sub-set of reviewed references.

Residues / Releases to land

The main pathway for releases to land will be through POP concentrations in grate ash and fly ash from the incinerators, which are disposed of to controlled landfill. The quantity of POPs contained in this ash depends on combustion conditions and types of abatement technology.

There is limited reliable information available on dioxin releases to land from hazardous waste incineration ash. According to the UNEP Toolkit (2005), a high standard of facility generates fly ash with a typical dioxin concentration of 30 µg I-TEQ/tonne of waste burned. Dyke (1997) and LUA (1999) used the range equivalent to 0.02 to 6.8 µg I-TEQ/tonne burned for various solid residues.

An average concentration of 15 µg I-TEQ/tonne is assumed for 2000 onwards as the midway point in the range from the UK studies for various residue types (Dyke 1997) and the UNEP Toolkit figure for fly ash.

The UNEP Toolkit (2005) also gives a concentration of 450 µg I-TEQ/tonne for fly ash in plants that have controlled combustion and good air pollution control, but are one level below the highest class of facility according to the toolkit’s system. This has been adopted as the concentration in 1990 for UK hazardous waste incinerators, with a linear decrease assumed from 1990 to 2000.

There is a high uncertainty in relation to these assumed emission factors and their applicability to abatement systems in use at the plant. The quantities of ash produced were not recorded.

Emissions to landfill for PCB has assumed to be the same as healthcare waste, while this approach will increase uncertainty in the emissions quoted, these waste streams are likely to be closer in terms of plastic and POPs generation than municipal waste streams.


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The UNEP toolkit assumes that 3% of the waste load burnt will be converted into fly ash; with the BIPRO waste report quoting an emission factor of 0.1 mg/kg of ash generated. These values have been scaled across all years of the time series to give PCB emissions in ash to landfill as 890 g in 1990 decreasing slightly to 880 g in 2006. The uncertainty in these values should be noted and data used only as a guide. No data has been found on the HCB content of ashes

Releases to Water

Releases to water will occur as waste effluent following treatment of wet effluent streams from the plant. The treatment plant will generate sludges which will be sent either for incineration or to landfill. The effluent from the on-site treatment works will be discharge to sewer where it will be further treated or directly to a water body if appropriate discharge conditions are met

Literature emission factors have been used to calculate emissions within the current estimates, and it is recommended that for future inventories emissions should try to be derived from pollution inventory data, noting that currently there is no clear link between activity, quantities of water used and concentrations of waste flows.

LUA (1999) quotes releases of 0.06 – 3.7 µg ITEQ/t of waste. The current estimates have used the centre of the range of 1.88 µg ITEQ/t of waste. This leads to an estimated effluent discharge of 0.55 g I-TEQ per year for all years.


The activity of hazardous waste incinerators has declined over the time series as solvent waste have been used as fuels for the cement industry. Levels of abatement are high. Throughput will depend on economic factors and measures to further reduce emissions.

1.22.6 Results

A graph of results summarising the emission estimates to air, land and water from waste incineration in the UK and a table of the time-series of emissions is shown at the end of the chapter.


Hazardous waste incineration is strictly controlled and is not a significant contributor to total emissions of POPs. This sector is therefore a low priority for improving the inventory, however possible recommendations will be to review the activity and emissions data for further disaggregation between high and low chlorinated wastes. It is also recommended that emissions for waste water need to be better understood and more closely geared towards UK industry through use of the pollution inventory data to provide activity and emissions.

1.23 Incineration: Healthcare Waste (6C)


The waste stream within the healthcare sector including hospital, veterinary and dental wastes has the potential to contain greater quantities of plastics and POPs generating materials. It will not normally include office waste form these activities which is typically segregated.


Clinical waste incinerators tend to deal only with clinical waste. At the start of the time period these were onsite at hospitals and simple combustion chambers with no abatement equipment. During the 1990s the quality of plant improved dramatically as new merchant plant were built to replace a large number of small plant. The activity data used within the NAEI has been based on AEA estimates from a variety of sources including capacity information of known plants and estimates at quantities generated. In the case of dioxins the emissions are based on emission data taken from the pollution


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inventories combined with the activity data to derive emission For PCB and HCB emissions have been based on the emission factors quoted by Dyke (1997) and Van der Most (1992) respectively.

Emission to Air: Dioxins

The emission factors derived from the NAEI range from 372 g I-TEQ/Mt in 1990 to 0.987 g I-TEQ/Mt in 2006. The UNEP toolkit (2005) quotes dioxin emission factors from 40,000 g I-TEQ/Mt to 1 g I-TEQ/Mt. This places the derived emission factors in the upper two classes of UNEP, with the 2006 value around UNEP class 4 – High technology, continuous furnace with sophisticated air pollution control system.


Few emission factors for HCB emission to air from clinical incinerators exist, with the main quotable reference coming from the UNECE guidebook. This quotes a range between 0.019 and 0.857 kg/Mt, against the Van der Most value of 500 kg/kt. Using this value however gives emissions to air between 180g in 1990 to 130g in 2006, meaning that this emission source is of low priority for HCB.


As an example to the figures quoted by Dyke has been adjusted to follow the decreasing stock of PCBs remaining; from 3.15 kg/Mt in 1990 down to 0.77 kg/Mt in 2006. The UNECE guidebook quotes values ranging from 0.002 and 23.2 kg/Mt. Emissions from the sector are low ranging from 1.1 kg down to 200 g in 2006.


The main pathway for releases to land will be through POP concentrations in ash from incinerators. These will be consigned to landfill.

The UNEP Toolkit (2005) gives concentration data from 150 to 920 µg I-TEQ/tonne for mix of bottom and fly ash for class 4 and class 3 healthcare waste incinerators as defined in the toolkit. The environmental performance and types of abatement technology used in the healthcare waste but it is assumed that the older healthcare waste incinerators in the UK were equivalent to the Toolkit’s class 3. LUA (1999) and Dyke (1997) give concentration data from a range of sources of 2.25 to 45 µg I-TEQ / tonne burned for grate ash, 144 to 360 µg I-TEQ/tonne for dry scrubber residue and 27.2 µg I-TEQ/tonne for wet scrubber residue. An estimate for concentration of 450 µg I-TEQ/tonne has been adopted, taking into account the above information. PCB concentrations in ash generated have been calculated using UNEP to gauge ash generation (assumed as 3% of load to generate fly ash, with bottom ash quantities not calculated) and emission factors from the BIPRO report (0.1 mg/kg of ash ).

Releases to Water

Emissions to water are unlikely for this sector with any emissions being negligible.


Emissions from the clinical incinerator sector are likely to be stable.

1.23.3 Results

A graph and table of NFR sector 6C emissions are shown at the end of this chapter.


While emissions of all POPs are likely to decline across the time series with improvements in facility technology and tightening abatement laws under the Waste Incinerator Directive (WID), emissions for the early part of the time series will be high.


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This is due mainly to the nature of waste stream and high levels of plastics incinerated, and also due to the absence of abatement on older facilities. Modern facilities will comply with stringent incinerator regulations meaning a reduction in POPs emissions.

It is also recommended that there needs to be greater understanding of waste management for ash generated in this sector and likely concentrations of POPs in ash, where uncertainties are likely to be at their highest.

1.24 Incineration: Sewage Sludge (6C)

1.24.1 Sector Description (NFR Code 6C) (SNAP 090901)

This sector will covers the incineration of sewage sludge. Due to the wet nature of the raw materials being destroyed and the regulatory issues sewage sludge is rarely used as a fuel in other industries although the power sector explored its use. There are a relatively small number of sewage sludge incinerators which have a number of combustion designs but strict emission controls to comply with the Waste Incineration Directive since 2000.


The activity data within the NAEI is based on estimates.


The emission factors used for the NAEI emissions are 68 g I-TEQ/Mt in 1990 dropping to 0.069 g I-TEQ/Mt by 2006 as abatement controls improved. In comparison the UNEP toolkit (2005) quotes emission factors ranging from 50 – 0.4 g I-TEQ/Mt depending on levels of abatement. This suggests the current estimates run from worse than class 1 (worst level) emissions down to close to the figure quoted for class 3 (best level of abatement).


The emissions of PCBs to air have been based on estimates for both activity data and emission factors within the NAEI is from 5.3 kg/Mt in 1990 to 1.93 kg/Mt in 2006. As a means of comparison the Dyke (1997) paper on PCBs also quotes emission factors, from Murphy et al (1985) of between 5.7 – 2.3 kg /Mt of waste incinerated. The UNECE guidebook quotes a static emission factor of 5 kg/Mt, although it should be noted that the same emission factor is also used for hazardous and municipal waste. The estimated emissions from this source are small in comparison to the overall inventory;, between 200 – 400 g of PCB per year.


No data are available on emissions of HCB from sewage sludges.


The most likely emission to land will be through the generation of contaminated ash consigned to landfill. The UNEP toolkit quotes emission factors for ash based on tonnes consumed as 23 g I-TEQ/Mt for class 1 (poor abatement) and 0.5 g I-TE/Mt for class 2 and 3.

Dyke (1997) quotes UK specific estimates of 0.98 g I-TEQ/Mt. For the current estimates the Dyke emission factor has been assumed for the older part of the series (1990 – 1999) and that UNEP class 2 will be used from 2000 onwards. This will reflect improvements in abatement. Releases are small at less than 0.1 g I-TEQ for all years of the time series.

Releases to Water

No information is available on potential releases of POPs to water from sewage sludge incineration.



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Sewage sludge disposal to land is limited for some sources as a result of the metal contamination in the sludge and opportunities are limited in dense urban areas hence incineration levels are likely to remain or increase however other technologies such as anaerobic digestion may become popular depending on the impact of the Government’s Renewable Energy Strategy on the sector.

1.24.3 Results

A graph and table of NFR sector 6C emissions shown at the end of this chapter.


Sewage sludge incineration is unlikely to be a significant contributor to total emissions of POPs. This sector is therefore a low priority for improving the inventory.

1.25 Incineration: Crematoria (6C)

1.25.1 Sector Description (NFR Code 6C) (SNAP 090901)

This sector is the disposal of human remains by cremation and their disposal generally to land but occasional to sea or water courses.


Activity data is precise to the nearest individual and is published by the Cremation Society.


The emission factors of 41.2 µg I-TEQ / cremation for 1990 and 1995, reducing to 24.7 µg I-TEQ / cremation by 2000, from the UK NAEI, have continued to be used for the current estimates. These values fall within the range quoted by the UNECE guidebook. Cremation emissions vary depending on the post combustion design of the flue systems. Measurements made in the mid 1990s showed higher concentrations than more recent measurements as significant investment was made in new plant.


No data are available on emissions of PCBs from crematoria.


The emission of HCB from cremations has been based on the Van der Most (1992) emission factor of 0.5 kg/Mt of waste converted into 0.5 kg/million cremations. This suggests that the combustion activity for each cremation would equate to that of a tonne of municipal waste which is likely to be an over estimate. The NAEI quotes current HCB emissions to air as 220 g in 1990 decreasing to 210 g in 2006. However this is felt to be an overestimate and in the absence of cremation specific measurements t he current estimates exclude this source from the inventory.


The main pathway for releases to land will be through concentrations of POP in ash from crematoria. The UNEP Toolkit (2005) gives concentration data from 2.5 µg I-TEQ/cremation, and this emission factor has been applied in the absence of any other data. LUA (1999) also quotes an emission factor of 1.34 µg I-TEQ/cremation, but the uncertainty in this value is likely to be greater. The ash generated is likely to have been disposed directly to land as residues.


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Releases to Water

No information has been identified on the fraction of ash which is disposed of at sea or to inland water courses. The latter is discouraged on environmental grounds and the release is likely to be negligible.


Cremation is seen as a popular alternative to burial with activity potentially likely to remain at least at current levels. The emissions from this sector are likely to continue to be small.

1.25.3 Results

A graph and table of NFR sector 6C emissions shown below, followed by a full list of references used for NFR 6C


Crematoria are unlikely to be a significant contributor to total emissions of POPs. This sector is therefore a low priority for improving the inventory.


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UK POPs Emissions: 6C Incineration, 1990-2006

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1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

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dio

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s

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6.000

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CB

DIOXIN AIR DIOXIN LAND DIOXIN WATER PCB LAND DL PCB LAND

PCB AIR HCB AIR DL PCB AIR


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Table: 6C Incineration practices (MSWI, Hazardous waste, Clinical waste and Sewage Sludge) POPs Emissions in the UK, 1990-2006

Table: 6D Other Waste Disposal POPs Emissions in the UK, 1990-2006


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1.25.5 References (NFR 6C)

• Berdowski J.J.M., Baas J, Bloos JP.J., Visschedijk A.J.H., Zandveld P.Y.J. (1997) The European Atmospheric Emission Inventory for Heavy Metals and Persistent Organic Pollutants. Umweltforschungsplan des Bundesministers fur Umwelt, Naturschutz und Reaktorsicherheit. Luftreinhaltung. Forschungbericht 104 02 672/03. TNO, Apeldoorn, The Netherlands.

• BREF Note for waste incineration (2006) published by the European Commission. ftp://ftp.jrc.es/pub/eippcb/doc/wi_bref_0806.pdf

• Cohen et al. (1995) Quantitative Estimation of the Entry of Dioxins, Furans, and Hexachlorobenzene into the Great Lakes from Airborne and Waterborne Sources, Center for the Biology of Natural Systems, Flushing, NY.

• Cremation Society data. Cremation Society of GB website at http://www.srgw.demon.co.uk/CremSoc4/Stats

• Dyke (1997) – A review of dioxin releases to land and water in UK

• Dyke et al (1997) Releases of PCBs to the UK environment, Report to ETSU on behalf of DETR

• HMIP Report (1995), A Review of Dioxin Emissions in the UK, Report No HMIP/CPR2/41/1/38, October 1995

• LUA 1999 – Releases of Dioxins to Land and Water in Europe

• Solid Residues from municipal waste incinerators in England Wales (2002) Published by the Environment Agency (UK)


• UK NAEI 1990 – 2006

• UNECE guidebook (2007)

• UNEP Toolkit (2005)

• Van der Most et al (1992), Emission Factors Manual PARCOM-ATMOS, Emission Factors for Air Pollutants, TNO report No 92-235, December 1992


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1.26 Other Waste Disposal: Agricultural Burning (6D)

1.26.1 Sector Description (NFR Code 6D)

This section covers agricultural combustion practices, mainly the open burning of agricultural wastes, such as crop residues, wood, leaves, animal carcasses, plastics and other general waste. The following provides a summary of the main potential activities under the sector of agricultural combustion:

• The open burning of crop residues (e.g. stubble burning) is a significant potential source of some POPs however stubble burning is now only legal in Scotland and Northern Ireland. Hedge trimmings and diseased crops may still be burnt at the site of production.

• The practices involving the open burning of a variety of plastic wastes on farms, such as waste silage wrap, empty chemical and fertiliser containers and bags. This activity is particularly relevant to POPs emissions.

• Open burning of wood and other organic farm wastes is likely to often be carried out at farms, possibly with plastic wastes mixed in. In addition, a small but significant proportion of the wood burned at farms is likely to have been treated (e.g. old fence posts).

• The practice of burning animal carcasses is another potential source of POP emissions, however this practice is taken under waste incineration though animal pyres from the Foot and Mouth outbreak of 2001 are included here.


The practices described that fall under the current heading are discussed separately below:

Field Burning

The practice of ‘stubble burning’ to remove unwanted vegetation and prepare fields for the next rotation of crop was banned in England and Wales in 1992, with an exemption for Linseed stubble which was banned in 1993. Enquiries in Scotland has established that given the market for straw this practices is currently very limited to potato hulms to prevent blight. The current NAEI estimates are based on activity data from MAFF (Ministry of Agriculture, Food and Fisheries) with an emission factors from the HMIP (1995) report. While there may be some uncertainty in these figures they represent the best available data and have been retained in the current estimates.

Agricultural Waste Burning

Traditionally agricultural waste burning would have covered a variety of ‘fuels’, both organic, such as waste vegetation and wood, and ‘man-made’, such as farmyard plastics, and drums contaminated with pesticide. Estimates of this activity are 86 kt per annum (Wood, 2005). As of 2006, the burning of farm plastics was banned (Defra), as well as the setting up of the ACFP (Advisory Committee on Farm Plastics) to help develop a collection and recycling scheme for plastic materials on farms.

This means after 2006 the quantities of agricultural waste destroyed should decrease significantly, This should also suggest a significant decline in the quantity of POPs to air generated. However these effects will fall outside the realms of the current time series, 1990 – 2006.

There has also been effort made from within the farming industry to improve emissions linked to combustion of farm plastics. A major use of plastic on farms, silage wrap, is now made from polyethylene whereas earlier a variety of materials were used including PVC which could potentially under poor combustion conditions lead to high POPs emissions. The use of PVC drums for pesticide residue and the former advice that these should be burnt may also have led to significant release prior to the 2006 ban.


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The NAEI activity data is based on an Environment Agency survey (2003), which has been used for all years of the time series. Emission factors for waste in the case of dioxins have been based on two literature papers. One based on sample monitoring from Coleman (2001) and the HMIP report (1995). As these emission factors are based on monitoring they represent the best available data. This however has generated a ‘snap shot’ or emissions, with the same emission factor scaled to all years. There may be uncertainty for earlier years of the time series where the make up of agricultural waste streams were different.

Animal Pyres

In 2001 the UK farming industry was devastated by an outbreak of foot and mouth disease, which led to the destruction of thousands of livestock. A proportion were burnt on open pyres. This process had the potential to generate dioxins all be it in small quantities per head of livestock. The NAEI emissions for this activity have been based on activity data provided by the National Audit office for numbers of animals cremated, broken down further by species. This has been used in conjunction with AEA estimates for emissions per head of livestock. In this case the activity data used should have a degree of certainty while the emission factors used likely represent estimates validated by carefully monitoring of dioxins and PCBs around several of the major pyre sites. The current estimates have been based on those in the NAEI.

Straw burning furnaces

The practice of burning straw in furnaces provided farmers with a renewable and potentially economic source of heat. Since the practice of field burning was banned in the UK in 1992/3, the practice of straw burning in furnaces has become increasingly popular.

The activity data used within the NAEI is based on DUKES which provides a constant value of 0.2 Mt. DUKES states that the quantities of straw consumed in burning have been based on estimates from 1990 and a survey carried out in 1993/4. It is possible to use straw on a commercial scale and thee is one electricity generating plant near Ely, Cambridgeshire. The combustion of straw to generate electricity would warrant the plant as a power generation site with emissions included under NFR 1A1a. The current emissions are for the combustion of straw for heat .

The emission factors for straw burning within the NAEI have been based on the HMIP (1995) report and Dyke (1997) for dioxins and PCB respectively. The NAEI emission factors have been repeated in the current set of emissions.

A full table of references for activity data and emission factors to air used within the NAEI is shown in the table on the next page.


Emissions of dioxins quoted both by the NAEI and the current estimates show a decline in dioxin emissions between 1990 and 2006. The emissions for stubble burning drop from 57 g-ITEQ in 1990 to 35 g I-TEQ in 1992 (0.75 g I-TEQ in 1993 for stubble burning of Linseed) at the time stubble burning was banned. The emissions for waste burning (35 g I-TEQ) and straw burning furnaces (6.72 g I-TEQ) remain constant across all years reflecting the fact the activity and emission factors are constant. Emissions from pyres are quoted only for 2001 0.94 g I-TEQ.


No data are available on the emission of HCB from this sector.


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Table 1.26 Reference Sources used within the inventory for 6D Other waste burning


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Continued


As with dioxins the overall emissions from this sector decline across the time series. Emissions of PCB from stubble burning decline from 1.14 kg in 1990 to 0.71 kg in 1992 (emissions from burning of fields for Linseed in 1993 are 0.015 Kg). Emissions for waste burning (59.45 kg) and straw burning furnaces (0.58 kg) remain constant for all years as emission factors and activity data are constant. The emissions from agricultural waste burning are the main sources for this sector 59 kg in 2006 of a total for NFR 6D of 265 kg).


Open burning of crop residues:

The UNEP Toolkit provides a concentration factor of 10 µg I-TEQ / tonne of material burned in the open burning of crop residues, and this factor has been applied in this study. All combustion residues will remain on the land and should therefore be considered a direct release to land.

Open burning of agricultural waste:

The UNEP Toolkit provides an emission factor of 600 µg I-TEQ/tonne for the open burning of MSW, which represents the best match within the toolkit. The DEFRA (2006) study on dioxins from domestic sources provides an emission factor of 100-2400 µg I-TEQ/tonne for domestic waste burning. The UNEP Toolkit emission factor has been applied for this study. It is assumed that all ash / residue material would have been disposed as a direct release to land.


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Combustion of straw There is limited data available on dioxin emission factors and releases from ash from straw burning in heating furnaces. The current estimates have been based on Dyke (1997) for both dioxin and PCB. In the case of dioxin an emission factor of 14 g I-TEQ/Mt of fuel burnt has been used. Given that the activity data remains the same for all years this produces an emission to land of 2.8 g I-TEQ per annum, and falls within the range quoted by Dyke (0.2 – 10 g I-TEQ). For PCB emissions, again based on Dyke, ash generation has been derived at 17% w/w of material burnt together with an emission factor of 0.71 µg /kg of ash generated. Emissions of PCB to land from this source are extremely low at 0.014 kg per annum. In all cases it is likely that all this ash is disposed directly to land, and not in a controlled landfill.

Releases to Water

Releases to water are likely to be negligible, although there is potential for run-off of POPs from solid residues into local water courses. As the first release is to land this has not been estimated


The ban on burning of field residues has already been accounted for within the current estimates, however the ban on burning of agricultural wastes, particularly plastics did not fully come into effect until 2007. This should see a further reduction in emissions.

1.26.3 Results

A graph summarising the emission estimates to air, land and water from all of the 6D Other Waste Disposal activities in the UK, including Agricultural waste burning, natural and accidental fires, and other open burning is shown at the end of the chapter. A table of the time-series of emissions is shown together with the table for NFR 6C at the end of the Incineration chapter (NFR 6C).


While some of the quoted emissions in the current estimates come from sources which no longer occur such as field burning and animal pyres or will be controlled from 2007 onwards. The emissions from straw burning are based on static activity and emission factors. Likewise the emissions associated with burning of agricultural wastes will have a high level of uncertainty as the nature of the waste and the method of burning will vary widely from fire to fire. The reduction in PVC used in agriculture may lead to reduced emissions in future to both air and land. The ban on burning of farm wastes (other than vegetation) will see these emissions fall further in future years post 2007.


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1.27 Other Waste Disposal: Natural and Accidental Fires (6D)

1.27.1 Sector Description (NFR 6D)

Accidental and natural fires are poorly-controlled combustion events that release large quantities of POPs into the environment. These can include accidental fires at houses, other buildings, cars, etc, as well as accidental and natural fires of woodland, grassland, moors, bogs, etc.

There are major uncertainties related to inventory development for accidental fires, for example:

• The variety of materials burnt, which can lead to difficulty in generating appropriate emission factors.

• The size and duration of fires greatly vary.

• The fire fighting technique used affects the release of POPs into the environment e.g. speed of fire extinguishment, method of collection of residual remains of fire (in terms of potential releases to land) and the collection of water from fire fighting.

• The handling and management of collected residual materials from fires will vary. For example, some materials from fires at buildings could be handled as special / hazardous waste or as construction and demolition wastes.

• Fires involving chlorinated chemicals (especially PCBs or PCPs) have particular potential for release of dioxins and PCBs. The potential for fires at electrical stations and transformers may release PCB s and furans although this has reduced due to the phase out of these transformer types

• Fires at landfills and tyre dumps may also release POPs to the environment

• The absence of statistics which relate to the scale of activity except for vehicle fires.


Accidental Vehicle Fires:

The activity data used within the NAEI is based on estimates taken from the fire statistics reported by the DCLG and formerly ODPM or the Home Office and emission factors from Wichmann (1995). While vehicles vary in their contents and composition they are more similar than some other Sectors. However the emission estimates are based on only one study of the formation of POPs during vehicle fires.

Accidental House and building Fires:

The NAEI uses a method based on the UK population and an emission factor from Lorenz (1g I-TEQ/million people) to estimate dioxin releases. However the emission of PAHs (Poly Aromatic Hydrocarbons) within the NAEI are based on a more detailed method. This uses the UK Fire Statistics and AEA estimates of the material burnt in each classification of fire to derive an estimate of the mass of material burnt. Using the PAH method to generate an activity statistic and the UNEP emission factor of 400 µg I-TEQ/t of material burnt gives an alternative estimate. The two methods can then be compared.

Accidental Fires in vegetation and woods:

The emissions of accidental fires in vegetation and woodland are difficult to establish activity and emission factor data for. Unlike vehicle and building fires where quantities burnt can at least be estimated, the size of this kind of fire will vary greatly, as will the nature of the material burnt. The intensity of the fire will affect the releases as will the amount of material


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burnt. Currently the activity data quoted within the NAEI comes from an AEA estimate used with the emission factors quoted in the HMIP (1995) report.

Emission to Air: Dioxins

Vehicle Fires:

Wichmann (1995) quotes an emission factor of 44 µg I-TEQ/per vehicle. Activity data fluctuates from year to year in inverse relationship to the price of scrap cars with emissions ranging from 2.4 – 4 g I-TEQ over the time series.

Accidental Building Fires:

The NAEI dioxin method used a constant emission factor based on population was based around population causing emissions to rise from 58 g I-TEQ in 1990 to 60 g I-TEQ in 2006. The emission of dioxins from house fires are likely to relate to the materials burnt and the combustion conditions which tend to be poor, but also the fire fighting techniques used and the speed at which the fire is put out. The increased incidence of smoke detectors both in home and work place would expect the speed of detection and response and hence to lead to an improvement in emissions. Using a method currently employed to estimate activity for PAH with the UNEP emission factors shows a decrease in emissions from 58 g I-TEQ in 1990 to 39 g I-TEQ in 2006.

Accidental forest and grassland fires:

Constant activity and emission factors have been used for all years in the absence of appropriate data. . However emissions from this source estimated to be small at 5.8 g I-TEQ per year.


No data are available on HCB emissions from accidental fires.


Currently within the NAEI no estimates for emissions of PCB to air are made for this sector, given that vehicle and building fires will almost certainly contain plastic materials the emission of PCB are likely for this source as dioxins are formed. The emission factor for PCB emissions to air for vehicle and building fires has been assumed to be the same as MSW waste burning (510 kg/Mt of fuel). This was selected as the materials burnt are similar (containing at least some plastic). The emission factor for field burning (0.29 kg/Mt) has been assumed for accidental vegetation and woodland fires, and this is likely to be a reasonable match.

The emissions of PCB from vehicles fires within the current estimates range from 1.4 kg per annum to 2.6 kg per annum. The emissions of PCB from houses and buildings within the current estimates range from 74 kg per annum to 50 kg per annum, and represent a more significant source. The emission of PCB to air from fires in vegetation is extremely low, with a constant figure of 0.0001 kg per annum.


The UNEP toolkit (2005) quotes the same emissions for dioxin to air as dioxin to land, (figures quoted are for residue as ash concentration). These are quoted as 18 µg I-TEQ/ per vehicle and 400 µg I-TEQ/t of material for building fires. The uncertainty in these figures is likely to be high. In lieu of better data these have figures have been used on the available NAEI data. The emission in this case will be as dioxin concentrations in ash, which will largely go to landfill.

Releases to Water

Releases to water depend on fire fighting techniques, but could be significant in terms of concentrations of POPs in run off water. This would be very difficult to estimate and there is


131 AEA

no adequate data available. In addition, there is potential for double counting of releases to the environment.


The potential future releases of POPs to the environment from accidental fires are difficult to predict. The number of such fires might increase in future, but fire fighting response times and methods are likely to continue to improve. The better use of smoke detectors in buildings is likely to further improve this due to earlier response rates to fires.

Overall, it is considered that the release of POPs to the environment from accidental fires is likely to fluctuate each year as present, with the overall average release per year likely to remain constant or decrease slightly.

1.27.3 Results

The graph of NFR sector 6D emissions is shown at the end of the chapter and includes the emissions from all of the 6D Other Waste Disposal activities in the UK, including agricultural waste burning, natural and accidental fires, and other open burning. A table of results is also shown at the end of the incineration chapter together with the table for NFR 6C.


The uncertainty in all estimates from this sector is large. The current estimates have also included PCB emissions for the first time noting that the NAEI does not currently provide estimates for PCB emissions to air from accidental fires.

While it is possible to gather data on the number of vehicle and building fires it is more difficult to gauge size and frequency of fires with vegetation and woodland. The current activity data used within the NAEI comes from an AEA estimate. It is recommended that resources be used to generate more accurate activity statistics.


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1.28 Other Waste Disposal: Other Open Burning (6D)


This section covers the following emission sources:

• Domestic bonfires (includes equivalent types of bonfires on farms)

• Burning of domestic solid waste – both indoors and outside

• Open burning of construction wastes

• Tobacco smoke. Domestic bonfires include a variety of garden wastes (e.g. wood, leaves, etc) but their importance with respect to POPs emissions is greatly increased where other wastes are added to the bonfires.

In addition, this section includes the open burning of wood from construction and demolition sites. Some of this wood will have been treated with chlorine containing wood treatment chemicals such as lindane or pentachlorophenol, which has the potential to lead to significant dioxin emissions.


The quantity of material burnt through bonfires are not recorded in any formal statistics. Local Authorities were contacted to asses s whether records of complaints might be of assistance however few of the sample of authorities contacted maintained records of the number of such complaints which in any case do not directly relate to the incidence of bonfires or the size of any bonfires.

The emissions will be greatly influenced but the type of material burnt. In the case of bonfires this will largely be garden waste, but where other wastes are included particularly plastics the incidence of POPs will increase greatly. This will also be the case on construction sites where treated wood is burnt.

The current estimates quoted within the NAEI have been based on estimates of activity for bonfire burning and burning of wastes. These largely centre around the review conducted by Coleman et al (2001), which also generated the emission factors used within the NAEI. Constant values for activity and emission factors have been used for all years. The quantities consumed within backyard burning is likely to vary from year to year. However the increasing levels of recycling suggest that the concentrations of plastic within bonfires should decrease. But limitations on collections may encourage this behaviour. The garden or yard burning of wastes is a major source in the emission inventory.

Two other aspects are covered within this sector: Firstly the incidence of emissions linked to fire works. While nationally fireworks are lit on a limited number of nights of the year, the volume of activity means that the potential emissions from this source are regarded by some as significant. Within the NAEI these emissions have been based on AEA estimates linked to a review of the nature and make up of fireworks reported by Passant et al (2004). The current estimates retain the method and numbers quoted in the NAEI.

Secondly the current sector will also include emissions from tobacco smoke. This source is not currently reported within the NAEI, and while emissions per cigarette are likely to be very small, the activity of smoking is sufficient that it is worth including this source within the current estimates. The activity data in this case has been based on the sales of cigarettes and tobacco from the Office of National Statistics with the emission factors quoted by the UNEP toolkit (2005), which is 0.1 pg I-TEQ/per cigarette.


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The emission trends to air for this sector show no change in the level of emissions as constant activity and emission factors are used. The dioxin emission quoted for burning of domestic and construction wastes is 51.8 g I-TEQ per year. While the uncertainty in this figure is high, it is probable that open burning of waste is likely to generate significant levels of dioxins.

The other emissions quoted from this sector within the current estimates are for fireworks/bonfires night, 5.8 g I-TEQ per year, and tobacco smoke emissions, 6.8 g I-TEQ.


No data are available on HCB emissions from these sources.


The emission of PCB from backyard burning of waste will relate to the composition of the material burnt and the quantity. The emissions quoted within the NAEI and repeated within the current estimates quote PCB emissions from this source as 152 kg per year. This source along with burning of agricultural waste (59.4 kg per year) dominate the PCB emissions for NFR 6D, and again in both cases this relates to the open, unabated combustion of plastics, particularly PVC. While in the case of agricultural combustion where burning of such wastes have been banned, implementing the existing regulations controlling the combustion of domestic wastes is more difficult to enforce or dissuade. The increase in recycling of wastes may help to reduce the quantities of plastic burnt, but estimates of emissions will likely always have high uncertainty, as surveys of wastes burnt are not made.

The emissions quoted both in the NAEI and repeated here should be used as a guide to emissions from this sector and treated with a due level of caution.


The same approach used to calculate emissions to land from ash generated in agricultural waste burning has been used to calculate emissions for domestic waste burning. The UNEP Toolkit has a concentration factor of 600 µg I-TEQ/tonne burned for open burning of MSW and this estimate has been continued for the current estimates in this inventory. As means of comparison, the DEFRA (2006) study gave emission factors of 100-2400 µg I-TEQ/tonne for domestic waste burning.

The majority of these releases are likely to be directly to land, rather than to a controlled disposal site.

The only estimate of the quantity of PCB released to land for this sub-sector comes from using information on the PCB content of Refused Derived Fuel ash, Dyke (1997) quotes contamination of ash from this fuel as 160 – 440 µg /t of ash generated. The worst case has been adopted using the 440 µg /t emission factor combined with an estimated 85 kt of material in bonfires. Emissions, likely to landfill, will be low at 0.037kg per annum, noting however that uncertainty in these emissions is extremely high.

Releases to Water

No data are available on releases to water, although these are likely to be negligible.


The practices of open burning of household waste, construction wood and bonfires (perhaps with plastics added) are likely to steadily decrease as both enforcement and environmental awareness increase. Therefore releases of POPs to the environment from these sources should decrease.


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1.28.3 Results

A table of results for NFR 6D is shown together with the table for 6C at the end of the incineration chapter (NFR 6C). A graph of NFR sector 6D emissions including the emissions from all of the 6D Other Waste Disposal activities in the UK, including agricultural waste burning, natural and accidental fires, and other open burning is shown at the end of this chapter.

1.28.4 Data Quality and Uncertainties

There is a high level of uncertainty within all the emissions quoted within the current sector. It has been noted that the emissions from backyard burning of waste are a key source of POPs. However there are no accurate records for the nature and quantity of waste combusted . One new set of emissions has been the inclusion of dioxins from tobacco smoke. While this source is likely to represent a small emission in the inventory overall it improves the completeness of the inventory.

1.28.5 References

• ACFP - http://www.defra.gov.uk/environment/waste/topics/agwaste/acfp.htm

• Coleman et al, (2001) Toxic Organic Micropollutant Monitoring 1999 to 2000, AEA Technology, Report No AEAT/R/ENV/0301 Issue 1, March 2001

• DEFRA (2006) Emissions of dioxins and dioxin-like PCBs from domestic sources.

• Digest of UK Energy Statistics (DUKES)

• Dyke (1997) – A review of dioxin releases to land and water in UK

• Dyke et al (1997) Releases of PCBs to the UK environment, Report to ETSU on behalf of DETR

• Environment Agency, (2003) Agricultural Waste Survey: A study of the management of non-natural agricultural waste on farms.

• Good. I. CIWM (2005), http://www.letsrecycle.com/do/ecco.py/view_item?listid=37&listcatid=244&listitemid=6962

• HMIP Report (1995), A Review of Dioxin Emissions in the UK, Report No HMIP/CPR2/41/1/38, October 1995

• Lorenz W. (1996) ‘Balance of the release of PCDD and PCDF during accidental fires”. Scientific paper.

• Office of National Statistics Data.

• Passant, et al (2004) NAEI Ad-hoc Improvement Programme: PM Emissions from Fires and Natural, Agricultural and Accidental Sources, AEA Technology, Report No AEAT/ENV/R/1809/Issue 1, September 2004

• UK Fire Statistics: http://www.communities.gov.uk/fire/researchandstatistics/firestatistics/firestatisticsuk/

• UK NAEI 1990 – 2006


• Wichmann, et al (1995) Release of PCDD/F and PAH during vehicle fires in traffic tunnels, Chemosphere, 31, No2


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UK POPs Emissions: 6D Other Waste, 1990-2006

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AEA

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