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Department of Chemistry
Umeå University
2012
Removal processes in sewage treatment plants -
Sludge quality and treatment efficiency of
structurally diverse organic compounds
Ulrika Olofsson
Copyright © 2012 Ulrika Olofsson
ISBN: 978-91-7459-356-3
Front cover: Richard Lindberg
Printed by: VMC, KBC
Umeå, Sweden 2012
Till Tove, Hanna, Wilma och Algot
Quidquid discis, tibi discis
“Vad än du lär dig, lär dig det för din egen skull”
Carpe diem
”Fånga dagen”
i
This thesis is based on the following papers, which are referred to
in the text by their respective Roman numerals (Papers I-V).
I. Richard H. Lindberg, Ulrika Olofsson, Per Rendahl, Magnus I. Johansson, Mats Tysklind and Barbro A. V. Andersson. Behavior of fluoroquinolones and trimethoprim during mechanical, chemical, and active sludge treatment of sewage water and digestion of sludge.
Environmental Science and Technology (2006) 40, 1042-1048.
II. Ulrika Olofsson, Staffan Lundstedt and Peter Haglund. Behavior and fate of anthropogenic substances at a Swedish sewage treatment plant. Water Science and Technology (2010) 62, 2880–2888.
III. Ulrika Olofsson, Eva Brorström-Lundén, Henrik Kylin, Peter Haglund. Comprehensive mass flow analysis of Swedish sludge contaminants. Submitted to Chemosphere.
IV. Ulrika Olofsson, Anders Bignert and Peter Haglund. Time-trends of organic contaminants in sewage sludge. Submitted to Water Research.
V. Ulrika Olofsson and Peter Haglund. Use of non-targeted environmetrics and comprehensive two-dimensional gas chromatography to assess sewage treatment plant removal efficiencies of structurally diverse organic contaminants. Manuscript.
Published papers are reproduced with kind permission from the American
Chemical Society (Paper I) and IWA Publishing (Paper II).
Contribution of the author of this thesis to the papers
Ulrika Olofsson was responsible for the following activities: planning of study
with co-author(s) (Papers I, II and V); sampling (Papers I, II and V) or sample
handling (Papers III and IV); laboratory work and instrumental analysis
(Papers I-V); evaluation and interpretation of the data (Papers II-V); and
writing the papers (Papers II-V). Ulrika Olofsson contributed to evaluation and
interpretation of the data, and writing the Paper I.
ii
BOD Biochemical oxygen demand
CMRs Carcinogenic, mutagenic and reprotoxic chemicals
DBT Dibutyltin
DEHP Di-(2-ethylhexyl) phthalate
DINP Di-iso-nonyl phthalate
d.w. Dry weight
EC European Community
EDCs Endocrine-disrupting chemicals
EHDPP 2-Ethylhexyldiphenyl phosphate
EPA Environmental Protection Agency
EU European Union
FQ Fluoroquinolone
GAC Granular activated carbon
GC Gas chromatography
GCxGC Two-dimensional gas chromatography
HRMS High resolution mass spectrometry
IS Internal standard
Kow Octanol-water partition coefficient
LC Liquid chromatography
LOQ Limit-of-quantification
LRMS Low resolution mass spectrometry
MBT Monobutyltin
MCCP Medium chain chlorinated paraffins
MF Mass flow
MRLs Maximum Residue Limits
MS Mass spectrometry
MS/MS Tandem mass spectrometry
NF Nanofiltration
NSAIDs Non-steroid anti-inflammatory drugs
OC Organic compound
OCDD Octachlorinated dibenzo-p-dioxin
OP Organophosphorus compound
i.e. organophosphorus flame retardant and plasticizer
iii
OTC Organotin compound
PAC Powder activated carbon
PAH Polycyclic aromatic hydrocarbon
PBDE Polybrominated diphenyl ether
PCA Principal Component Analysis
PCAs Polychlorinated alkanes
PCB Polychlorinated biphenyl
PCBz Polychlorobenzenes
PCDD/Fs Polychlorinated dibenzo-p-dioxins and furans
PFC Perfluorochemical
PFOS Perfluorooctane sulfonate
POP Persistent organic pollutant
PPCPs Pharmaceuticals and personal care products
PVC Polyvinyl chloride
RE Removal efficiency
REACH Registration, Evaluation, Authorization of Chemicals
RO Reverse osmosis
RoHS Restriction of Hazardous Substances
RS Recovery standard
SA Sludge adsorption
SPE Solid phase extraction
STP Sewage treatment plant
TBEP Tris(2-butoxyethyl) phosphate
TBP Tributyl phosphate
TCEP Tris(2-chloroethyl) phosphate
TCPP Tris(2-chloroisopropyl) phosphate
TDCPP Tris(1,3-dichloro-2-propyl) phosphate
TEQ Toxic equivalent
TOFMS Time-of-flight mass spectrometry
TPP Triphenyl phosphate
WFD Water Framework Directive
WHO World Health Organization
iv
Definitions
Aerobic stabilization and anaerobic digestion
Degradation of biodegradable materials by microorganisms occurs in
the presence or absence of oxygen, respectively, to reduce the waste
volume. Digestion also gives the opportunity to utilize the produced
energy, biogas.
Biochemical oxygen demand (BOD)
A measure of how much biodegradable material there is in the water,
i.e. the amount of dissolved oxygen needed by aerobic biological
organisms to break down organic matter present in the water in a
specific time-frame. BOD is often used as a measure of the STP process
effectiveness.
Mesophilic and thermophilic digestion
These digestions are operated at ca. 37°C or 55°C, respectively, viz. the
temperature at which microorganisms have the best growth to
generate high biogas production (in their respective area, 20-45°C and
<45°C).
Personal equivalent (pe)
A measurement of the amount of oxygen needed to break down the
organic matter that one person produces in one day. The amount is
measured as the oxygen that microorganisms consume over seven days
to break down the organic material in sewage water (BOD7). 1 pe is
equal to 70g BOD7/day.
Sanitation
Treatment of organic waste that significantly reduces the levels of
pathogens (disease-causing microorganisms) to the extent that there is
no risk to humans, animals and plants in the use of end product.
Storm water
Additional water, as roof water, drainage water and leaking rain water
and groundwater, added to the sewer system.
Substitution prefix
Mono (1) one Hexa (6) six Di (2) two Hepta (7) seven Tri (3) three Octa (8) eight Tetra (4) four Nona (9) nine Penta (5) five Deca (10) ten
LIST OF PAPERS .............................................................................................................................. i
ABBREVIATIONS AND DEFINITIONS ................................................................................... ii
1. INTRODUCTION ......................................................................................................................... 1 Main objectives and aim ........................................................................................................................ 10
2. TARGET COMPOUNDS ......................................................................................................... 13 Selection of compounds......................................................................................................................... 13 Sources and use patterns ...................................................................................................................... 17 Physicochemical characteristics of the contaminants ............................................................ 17
3. THE SEWAGE TREATMENT PLANTS ............................................................................ 19
4. SAMPLE COLLECTION AND CHEMICAL ANALYSIS ................................................ 23 Sampling ....................................................................................................................................................... 23 Chemical analysis ..................................................................................................................................... 24 Data evaluation .......................................................................................................................................... 28
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY ............................................. 33 Behaviour and fate of sewage contaminants .............................................................................. 34 Swedish sludge quality .......................................................................................................................... 42
6. TIME-TREND ANALYSIS ..................................................................................................... 51 Mass flows and time-trends ................................................................................................................ 52 Action limits ................................................................................................................................................ 58
7. NON-TARGETED SCREENING OF POORLY REMOVED CONTAMINANTS ..... 61 Principal Component Analysis ........................................................................................................... 62 Assessment of the STP’s removal efficiency ................................................................................ 64 Tentative identification of poorly removed contaminants .................................................. 68
8. CONCLUDING REMARKS AND FUTURE PERSPECTIVES ...................................... 73 Conclusions.................................................................................................................................................. 73 Future aspects ............................................................................................................................................ 75
ACKNOWLEDGEMENTS ........................................................................................................... 81
REFERENCES ................................................................................................................................ 83
APPENDIX 1................................................................................................................................... A1
1
Large and ever-increasing numbers of chemicals, including large quantities of a
broad spectrum of organic compounds (OCs) are used in modern society. More
than 30 000 of the total number of more than 100 000 chemical substances
registered in the European Union (EU) are estimated to be used daily in Europe
(EC, 1990; Schwarzenbach et al., 2006). Many of these substances will be
discharged into the waste-streams handled by municipal sewage treatment
plants (STPs). The sewage that reaches the STPs originates from several
sources e.g. industrial sites, hospitals and households. The primary purpose of
sewage treatment is to reduce nutrient loads and biochemical oxygen demand
(BOD). However, another important purpose is to act as a partial barrier,
reducing the amounts of carcinogenic, mutagenic and reprotoxic chemicals
(CMRs), persistent organic pollutants (POPs), pesticides, toxic metals and other
potentially harmful anthropogenic substances to levels (in both effluent and
sludge) that will not cause adverse environmental effects. After sewage
treatment the clarified water (effluent) is released into recipient water and the
final solid product is usually sludge that has been anaerobically digested or
aerobically stabilized, and then dewatered. Sewage sludge contains nutrients
and organic matter that can be used in agriculture for soil improvement,
provided that its contents of hazardous substances are sufficiently low.
The contaminant load in sewage streams handled by STPs is highly dependent
on the amount of chemicals used, and patterns of their use, in the communities
served by the STPs. Leakages from consumer products (rates of which depend
on the intrinsic properties of both the compounds themselves and the materials
used) also contribute to the load. Notably, the pharmaceuticals and personal
care products (PPCPs) used directly influence the load, while plastic additives
incorporated in many consumer products are indirect sources. Additional
important sources influencing STPs’ contaminant loads are the large-scale use
of industrial chemicals and stormwater-borne pollution originating from traffic,
other combustion sources and long-range air transport. A schematic diagram of
1. INTRODUCTION
2
the mass flows of chemical substances into the environment via STPs is
presented in Figure 1. The fate of chemical substances after reaching the STPs
during sewage treatment depends on the treatment process and the nature of
the compounds, both of which strongly affect the chemicals’ rates of
evaporation, biodegradation, sorption to sludge and discharge to recipient
water (Zitomer and Speece, 1993).
Figure 1. Schematic diagram of the mass flows of chemical substances derived from both internal and external milieus, via sewage systems to a sewage treatment plant (STP), then through effluent and sludge into the environment.
Numerous studies in recent decades have focused on levels of sewage
contaminants (in effluent and sludge), such as POPs and PPCPs. The results
indicate that many undesirable compounds can be present in STPs’ effluent
and/or sludge at potentially harmful concentrations. STPs can thus be
considered as secondary sources of anthropogenic substances released into the
environment (Harrison et al., 2006; Kinney et al., 2006; Song et al., 2006; Xia et
al., 2005; Zuccato et al., 2010). Once these substances have reached
environmental compartments such as surface water and soil they may pose
threats to aquatic and terrestrial organisms.
Industry HouseholdsHospitals
Sewage
STP
Effluent Sludge
Environment
Offices Public buildings
Traffic Long-range air transport
1. INTRODUCTION
3
Overview of sewage contaminant levels
Traditional OCs are predominantly lipophilic and thus have a high tendency to
sorb to and accumulate in sludge, to ng-mg kg-1 dry weight (d.w.) levels (Bossi
et al., 2008; Langdon et al., 2011; Lindberg et al., 2006; Marklund et al., 2005;
Ricklund et al., 2008; Stevens et al., 2003; Voulvoulis et al., 2004; Ying and
Kookana, 2007). However, the patterns are complex, and levels of several
important classes of potentially harmful compounds have declined recently.
Notably, levels of “traditional” POPs, such as polychlorinated biphenyls (PCBs)
and polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), in sewage sludge
have substantially fallen in recent decades (Clarke et al., 2008; 2010).
A comprehensive review of reported concentrations of emerging OCs in sewage
sludge (Clarke and Smith, 2011) in recent decades (1984-2009) concluded that
levels of polychlorinated alkanes (PCAs, industrial chemicals) are higher (480
mg kg-1 d.w. on average) than those of compounds originating from domestic
sources. For instance, average levels of di-(2-ethylhexyl) phthalate (DEHP, a
phthalate that is widely used as a plasticizer in polyvinyl chloride, PVC) and
triclosan (an antibacterial agent used in personal care products) were
reportedly 58 and 4.4 mg kg-1 d.w., respectively. Unsurprisingly, reported levels
of less commonly used industrial and domestic chemicals were much lower, e.g.
organotin compounds (OTCs), polybrominated diphenyl ethers (PBDEs) and
perfluorochemicals (PFCs), for which average reported levels were 0.93, 1.4
and 0.14 mg kg-1 d.w., respectively. They also concluded that concentrations of
PCAs are three orders of magnitude higher than those of PCBs.
Several classes of pharmaceuticals have raised concerns for various reasons.
For instance, the intensive use of antibiotics throughout the world may have
profound effects on microbiological communities in the environment and
enhance risks of antibiotic resistant strains of bacteria developing (Giger et al.,
2003; Holzel et al., 2010). Many of the antibiotics (and other pharmaceuticals)
administered in human medicine are excreted unchanged, mainly in urine and
faeces, and disposal of unused medicine may also be an important source of
these substances. The main route for transportation of these substances to the
environment is via STPs (Choi et al., 2008; Zuccato et al., 2010), thus there is
obvious interest in their fates in STPs, and concentrations of antibiotics have
been determined in sewage water, hospital wastewater, ground and river
water, sludge, soil and manure. Reported concentrations of antibiotics range
from sub or low ng L-1 levels in groundwater and rivers to high g L-1 in
1. INTRODUCTION
4
hospital effluent water. Concentrations in STP effluents range between these
extremes, with reported sludge levels in the mg kg-1 d.w. range (Giger et al.,
2003; Golet et al., 2003; Lindberg et al., 2004; Spongberg and Witter, 2008;
Zorita et al., 2009).
Fate and behaviour of sewage contaminants
The fate and behaviour, in terms of removal efficiency and mass balance, of
emerging and priority compounds, e.g. POPs and PPCPs, have also been
extensively studied during the last decade. Dargnat et al. (2009) and Peng et al.
(2009) found that about 78% of DEHP and 95% of PBDEs were removed from
sewage water handled by a French STP and STPs in the Pearl River delta, South
China, respectively. The high treatment efficiencies for these non-polar
compounds were attributed to their strong sorption to sludge. In contrast,
Marklund et al. (2005) concluded that the overall treatment efficiencies of
organophosphorus flame retardants and plasticizers (OPs) were inadequate at
Swedish STPs, although the treatment process removed alkyl-OPs better than
chlorinated OPs, which mainly tended to pass through the STP unaffected.
These findings are in good agreement with a study by Meyer and Bester (2004).
Most of the semi-polar and polar PPCPs have also low removal rates (Jelic et al.,
2011; Zorita et al., 2009), although the fluoroquinolones (FQs, antibiotics) and
triclosan partly partition to sludge (Bester, 2003; Lindberg et al., 2006; Nakada
et al., 2010). Semi-polar and polar sewage contaminants will thus reach the
STPs’ recipient water at almost the same levels that they entered the STPs.
These findings show that current sewage treatment techniques have limitations
for removing of water-soluble compounds.
Non-targeted screening of sewage contaminants
Most previous studies of effluent concentrations, mass balances and removal
efficiency of sewage contaminants have focused on a specific compound or
group of compounds. This can provide valuable information, but there is an
obvious risk that important contaminants may be missed. Therefore, there is a
need to develop and apply non-discriminating methods capable for
simultaneously determining hundreds, or ideally thousands, of chemicals in
STP influents and effluents. Towards this end, Semard et al. (2008) investigated
the potential use of comprehensive two-dimensional gas chromatography time-
of-flight mass spectrometry (GCxGC-TOFMS) for broadly screening hazardous
compounds in urban sewage water. They identified more than 1 000 chemical
1. INTRODUCTION
5
substances, most of which were removed or decreased during the sewage
treatment process. However, they did not evaluate the sewage contaminants
that were poorly separated, which may be important for improving the
performance of the STPs. More recently, a GCxGC procedure for automatically
searching and evaluating compounds in sewage effluent was developed by
Gomez et al. (2011). The richness of the two-dimensional “fingerprints”
acquired by their GCxGC method provides abundant information about the
contaminants present in the effluent. Such information can be highly valuable
for monitoring changes in sewage water quality, e.g. comparison of
“fingerprints” over time can provide valuable information about temporal
variations in levels of contaminants in STP effluents. However, the full potential
of GCxGC separation techniques has not yet been exploited in sewage
contaminant studies, and the exceptional peak capacity it offers (i.e. its ability
to separate many thousands of chemicals) needs to be combined with an
equally efficient study design and data evaluation protocol.
Environmental objectives for Swedish sewage sludge
In Sweden, approximately 1 000 000 tonnes, or 240 000 tonnes d.w. of sludge is
produced from STPs per year (Swedish EPA, 2007), with phosphorus and
nitrogen contents of ca. 3% (7 200 tonnes) and 3.5% (8 400 tonnes),
respectively. Thus, optimising use of these nutrients in the sludge is highly
important for maintaining phosphorus resources, which are globally depleting
(Steen, 1998). However, both within Europe and elsewhere there are diverse
opinions regarding the suitability of applying sewage sludge to land. For
instance, the Swedish government encourages this practice, while it is
restricted in Switzerland and most of the sludge is incinerated in The
Netherlands. Within the EU and the USA approximately 37% and 60% of ca. 9.9
and 5.6 million tonnes d.w. annually produced is used in agriculture,
respectively (NRC, 2002), and in Sweden ca. 15% is applied to land. Thus, the
Swedish use of sludge in agriculture is currently rather low.
Therefore, according to a Swedish government decision, by 2015 at least 60%
of the phosphorus originating from sewage should be returned to productive
soil, half to arable land (Swedish EPA, 2002). To achieve this nutrient recycling
goal, contents of hazardous substances in sewage sludge, and the risk of
spreading infections if the sludge is applied to sensitive land, must be reduced.
Further, the deposition of organic material, such as sewage sludge, on waste
dumps has been banned in Sweden since 2005 (Ministry of the Environment,
1. INTRODUCTION
6
2001). This has resulted in considerable interest in alternative applications for
such waste, e.g. as fertilizer for forested or other non-arable land (roadsides,
abandoned dump sites or open-cast mines, etc.), or incineration for energy
production. However, these options may hamper attempts to promote
sustainability and fulfil the goal of the Swedish National Environmental
Protection Agency (Swedish EPA) to increase the use of sludge in agriculture.
The greatest challenge may be to reduce the contents of hazardous substances
(such as POPs, toxic metals, pesticides, hormone-disrupting chemicals (EDCs),
carcinogens and pathogens) in sludge and sludge-amended soil sufficiently to
fulfil legal requirements and, equally importantly, to convince consumers and
consumer organisations that products grown on such amended soil are safe.
Guideline values of sludge contaminants and legislation
There are no legal limits, today, for OCs in sewage sludge intended for
agricultural uses. However, European Maximum Residue Limits (MRLs) (EU,
1986) have been established for metals, and implemented in various countries,
e.g. Greece, Ireland, Italy, Luxembourg, Portugal, and Spain. In addition, stricter
limit concentrations have been set in some other countries, e.g. Belgium,
Denmark, Finland, The Netherlands and Sweden (Ministry of the Environment,
1998). Sludge from Swedish municipal STPs generally complies with these
limits (Haglund and Olofsson, 2007; 2008; 2009; 2010; 2011) and suggested
limits in the European Community (EC) sludge draft directive “Working
document on sludge”, as outlined below (CEC, 2000). In the USA, the limits for
metals in biosolids (treated sewage sludge) applied to land are slightly higher
(U.S. EPA, 1993). The limit values for metals in sludge (for land applications) in
the EU, Sweden and the USA are summarized in Table 1. The more than 20-year
old EC sludge directive is currently under review and revision (CEC, 2011) and
in Sweden the EPA has submitted a proposal to amend the limits for metals.
1. INTRODUCTION
7
Table 1. Limit concentrations, mg kg-1
d.w., of metals in sewage sludge for use on land.
Metals EU EUa
Sweden Swedenb
USA
Cd 20 - 40 10 2 1.3 85
Cr - 1 000 100 100 -
Cu 1 000 - 1 700 1 000 600 600 4 300
Hg 16 - 25 10 2.5 1.0 57
Ni 300 - 400 300 50 50 -
Pb 750 - 1 200 750 100 100 840
Zn 2 500 - 4 000 2 500 800 800 7 500
Ag - - - 8 -
As - - - - 75
Ni - - - - 420
Se - - - - 100 aProposed limits in the EU (CEC, 2000).
bProposed limits in Sweden
(Swedish EPA, 2010).
Despite the lack of legal limits for OCs in sludge, recommended MRLs have been
set for three groups of organic “indicator” pollutants: six polycyclic aromatic
hydrocarbons (PAHs; sum, 3 mg kg-1 d.w.), indicator-PCBs (sum, 0.4 mg kg-1
d.w.) and 4-nonylphenol (50 mg kg-1 d.w.), through a voluntary agreement
between the Swedish EPA, the Federation of Swedish Farmers and the Swedish
Water & Wastewater Association (Swedish EPA et al., 1995). These pollutants
are included in the STPs’ monitoring programs and are reported in their annual
environmental reports. The EC sludge directive (CEC, 2000) also suggests limit
values for concentrations of total halogenated OCs (AOX, 500 mg kg-1 d.w.),
linear alkylbenzene sulphonates (LAS, 2 600 mg kg-1 d.w.), DEHP (100 mg kg-1
d.w.), 4-nonylphenol and nonylphenol-ethoxylates (NPEs, 50 mg kg-1 d.w.), nine
PAHs (sum, 6 mg kg-1 d.w.), indicator-PCBs (sum, 0.8 mg kg-1 d.w.) and
PCDD/Fs (100 ng TEQ kg-1 d.w.).
In addition, a number of OCs and metals are classified as priority substances in
the EU Water Framework Directive (WFD) (EU, 2000). Currently 33 priority
substances (of which 13 are classified as hazardous) are regulated by this legal
framework, and the list is under constant review. The increasing contamination
of natural water systems with anthropogenic compounds is a major problem
throughout the world, due to their largely unknown long-term effects on
aquatic life and human health, and the purpose of the WFD is to protect the
water quality in European countries. The Stockholm Convention on POPs
1. INTRODUCTION
8
(UNEP, 2001) is another legally binding agreement, which was adopted on May
22nd 2001, entered into force on May 17th 2004, and has been ratified by
numerous countries, including Sweden. POPs are of particular concern since
they are resistant to chemical and biological degradation and can remain intact
in the environment for long times. POPs also have a strong tendency to
bioaccumulate in fatty tissue of living organisms, and even at extremely low
concentrations they pose health risks to humans and wildlife. Currently (2011),
21 priority pollutants are listed under this global convention, but proposals
have been made to include a large number of other compounds in the protocol.
Today, most chemical restrictions apply across Europe under the REACH
(Registration, Evaluation, Authorization of Chemicals) Regulation (EU, 2006),
which replaced much previous chemical legislation. REACH entered into force
across the whole EU on June 1st 2007 and will be applied step by step in the
Member States. This Regulation stipulates that Member States, e.g. Sweden,
must implement its clauses either directly or through appropriate national
legislation. The basic framework consists of the REACH and CLP (Classification,
Labeling and Packaging; EU, 2008) regulations, which require knowledge and
labeling of all chemical substances manufactured in, or imported into, the EU.
REACH also covers mechanisms for risk assessments of hazardous compounds,
license requirements and use limitations. Some chemical substances are also
regulated by other product-specific directives, e.g. the use of cadmium,
mercury, lead, hexavalent chromium and the flame retardants polybrominated
biphenyl (PBB) and PBDEs in new electrical and electronic equipment in the EU
market has been prohibited since July 1st 2006 by the RoHS (Restriction of
Hazardous Substances) directive (EU, 2003).
These types of national and international environmental legislation and
regulations are intended to reduce levels of hazardous substances in the
environment in order to safeguard the sustainability of ecosystems and human
health. They have proven to be powerful tools for minimizing the release of
such compounds into the environment. National bans of PCBs in the 1970s and
the international regulation of POPs, including PCDD/Fs, in the Stockholm
Convention (UNEP, 2001), have resulted in substantial reductions of these
compounds in the environment. As mentioned earlier, there are also
indications that levels of PCBs and PCDD/Fs in sewage sludge have decreased
in recent decades (Clarke et al., 2008; 2010). However, these kinds of
regulation and legislation only cover parts of the enormous flows of chemicals
in the technosphere, thus intense efforts are being made globally to identify
1. INTRODUCTION
9
new or “emerging” pollutants that may have been overlooked or have been
recently introduced to the market. Furthermore, the potentially adverse
interactive or “cocktail effects” that combinations of a large number of
chemicals may have on the environment, and human or animal health, are
poorly understood and generally neglected.
Sewage sludge as a matrix for environmental monitoring
Even if sewage sludges are not recycled it is an important environmental
matrix for monitoring, to obtain socio-economic “fingerprints” of the OCs used
by the communities that generate them and for assessing the diversity and
abundance of the myriads of chemicals used today that end up in waste and
final recipient waters (both nationally and globally).
Therefore, in 2004, the Swedish EPA started to include sewage sludge in its
national environmental monitoring program to obtain an integrated
understanding of the types and amounts of hazardous substances circulating in
the technosphere that reach STPs, associate with sewage sludge, and may
subsequently leach into the environment. Since then, annual measurements of
prioritized sludge contaminants from selected STPs have been performed (in
one of the studies underlying this thesis, see below), allowing time-trend
analysis within a reasonable time-span. The sludge monitoring data can be
used to follow-up effects of regulatory actions, to screen new and emerging
compounds and to monitor the quality of the sewage sludge. In parallel to the
annual sampling for monitoring, subsamples are also taken for archiving in an
environmental specimen bank that will be valuable in the future for tracking
changes (trends) in sludge contaminant concentrations as consequences of
regulatory actions. Archiving sludge will also allow retrospective monitoring of
chemical substances that are not of concern today. Effects of future
substitutions of compounds by others, hopefully less toxic to humans and the
environment, can also be easily evaluated and validated by retrospective
analyses of archived sludge, which is essential from legislative, environmental
and toxicological perspectives.
1. INTRODUCTION
10
Main objectives and aim
The fate and behaviour of chemical substances during sewage treatment and
their levels in (inter alia) STP influent and effluent water, and sludge, have
received considerable global attention in recent decades. However, greater
knowledge of numerous associated phenomena is still required. The main
objective of the research this thesis is based upon was to improve
understanding of the relationships between the characteristics (structural and
physicochemical) of sewage contaminants and their sewage treatment
efficiency. Further objectives were to examine the relationships between socio-
economic uses of chemicals and sludge quality, and the effects of regulatory
actions on sludge quality. More specific aims were to enhance our knowledge
about:
the quality of the sludge produced by STPs, in terms of the contaminants
that accumulate in it, their mass flows (calculated from their levels in
sludge and annual national use levels), and the relationships between
the chemicals’ fates and physicochemical properties;
time trends in levels of sewage sludge contaminant concentrations (if
any are detectable over a reasonable time-span), and the effectiveness of
attempts to reduce the release of harmful substances into the
environment, e.g. through legislation and regulations;
the total STP removal efficiency of anthropogenic substances (influent
versus effluent levels) and the effectiveness of specific treatment steps;
the power of comprehensive GCxGC-TOFMS for unbiased (non-targeted)
characterization of sewage water (influent and effluent), and its utility
for identifying, quantifying and estimating the removal efficiency of
structurally diverse GCxGC-amenable OCs in sewage, especially those
that are poorly removed.
These results may facilitate identification of the upstream measures required to
reduce the inflow of undesirable substances to the STPs, and possible
improvements of sewage treatment processes to minimize the release of
undesirable compounds into the environment. They could also be useful for
risk assessments of sludge applications on land. Moreover, the data provide
detailed information about the environmental load derived from STPs,
especially Swedish STPs, which may be valuable for revising environmental
1. INTRODUCTION
11
legislation and restrictions, if necessary. Further, the possibility of using sludge
stored in the environmental specimen bank will greatly facilitate future studies
of established, emerging and new contaminants that are expected to
accumulate in sewage sludge. These kinds of studies can be very important for
overviews of current and future chemical flows in the technosphere, and their
possible environmental impact.
The papers appended to this thesis examine the behaviour and fate of
anthropogenic substances in an STP (Papers I and II) and the mass flows of
selected compounds used in the served society that are sorbed to sewage
sludge (Paper III). Paper IV presents time-trend analyses of sludge
contaminants, based on statistical evaluation of seven years of measurements.
Finally, the STP removal efficiency of non-targeted (poorly removed) sewage
contaminants was investigated using GCxGC-TOFMS (Paper V).
12
13
In the studies this thesis is based upon, 285 anthropogenic compounds in total
were investigated. CAS numbers and selected physicochemical properties of the
target compounds are presented in Table S1 of Supplementary data for Paper
III, and their molecular structures are shown in Appendix 1 of the thesis. Main
applications and the quantities used annually in Sweden (based on data from
2004) are summarized in Table 2, and their physicochemical properties in
Table 3. It should be noted that the annual quantities recorded in the Swedish
product register (Swedish Chemicals Agency, 2011) do not include chemicals
manufactured or imported in quantities less than 100 kg per company nor
those present in imported consumer articles. Therefore, the product register
can give misleading indications of amounts that could be potentially released
into the environment.
Selection of compounds
The sludge contaminants were selected by the authors of the appended papers,
in consultation with the Swedish EPA, from Scandinavian priority lists, the EU
WFD (EU, 2000), or the draft EC Directive “Working document on sludge” (CEC,
2000), some of which are classified as POPs (UNEP, 2001) or WFD priority
substances (EU, 2000), see Table S1 (Supplementary data, Paper III). The WFD,
EC sludge directive and Stockholm Convention on POPs are briefly described in
Chapter 1. The focus was on (semi-)lipophilic compounds that may be sorbed
on sludge, ignoring volatile compounds due to their potential to evaporate
during sewage treatment processes. Thus, only non-volatile and semi-volatile
compounds that are unlikely to evaporate much were included. Moreover,
these selected compounds are representative of a large portion of semi-volatile
OCs found in sewage sludge. By studying the levels of these sludge
contaminants we can create general knowledge about the Swedish sludge
quality. An overview of the diversity of the target compounds, in term of size,
polarity and functional groups etc. are given in Figure 2.
2. TARGET COMPOUNDS
14
Table 2. Main applications and quantities of the target compounds used annually (in Sweden)
Compounds na Applications
Quantityb
(103 kg year-1)
As, Cd, Co, Cr, Cu, Hg, Ni, Pb, V, Zn 10 Metals, ingredients in cosmetics 21 046
Phthalates 8 Plasticizers, e.g. in polyvinyl chloride (PVC), and additives in personal care products, e.g. in fragrances
73 964
Biocides 11 Killing living organisms 1 637
Polycyclic aromatic hydrocarbons (PAHs)
6 Products of incomplete combustion 1 203c
Adipates 8 Softening agents in plastics 1 073
Pesticides 109 Pest control 828
Polychlorinated alkanes (PCAs) 3 Lubricants and cutting fluids (metal working industry), flame retardants and plasticizers
298
Organophosphorus compounds (OPs)
8 Flame retardants and/or plasticizers in textiles, plastics and building materials
286
Butylhydroxytoluene (BHT) 1 Stabilizer in plastics and rubber, antioxidant (e.g. in processed food)
254
Organotin compounds (OTCs) 6 Anti-foulant and stabilizer in polyvinyl chloride (PVC)
240
Non-steroid anti-inflammatory drugs (NSAIDs)
4 Pharmaceuticals 84d
Siloxanes 7 Sanitary articles, lubricants and hydraulic fluids in textiles and skin care products
31
Perfluorochemicals (PFCs) 13 Water, fat or stain repellents for paper, textiles, carpets, etc.
24e
Terpene (Limonene) 2 Flavour and odour additive (hygiene products and perfumes)
17
Polychlorobenzenes (PCBz) 11 Dyestuffs and solvent for pesticides 8.1f
4-Nonylphenol 1 Detergent, surfactants (metabolite) 7.6
Fluoroquinolones (FQs) 3 Pharmaceuticals (antibiotics) 5.1d
Trimethoprim 1 Pharmaceutical (antibiotic) 1.0d
Polybrominated diphenyl ethers (PBDEs)
8 Flame retardants in electronics, furniture and building materials
3.6g
Triclosan (TCS) 1 Antibacterial agent in personal care products, e.g. in toothpaste and deodorants
3.1
Tetracyclines (TCs) 5 Pharmaceuticals (antibiotics) 1.3d,h
Hormones 4 Pharmaceuticals 0.07d
Chlorophenols (CPs) 19 Wood and textile preservatives Banned (1978)i
Polychlorinated biphenyls (PCBs)
WHO-PCBs
Indicator (I)-PCBs
12
7
Dielectric fluids in transformers and capacitors
Banned (1972)i
Polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs)
17 Unintentionally formed (by-products) -
an: number of compounds included in the group. Pesticides: insecticides, herbicides and fungicides.
bAnnual quantity used in Sweden in 2004 (Swedish Chemicals Agency, 2011). cQuantity of benzo(a)pyrene. dSwedish MPA (2004). eSwedish Chemicals Agency (2006). fQuantity of 1,2-dichlorobenzene. gQuantity of PBDE 209. hDemeclocycline and chlorotetracycline not included. iIn Sweden.
2. TARGET COMPOUNDS
15
Table 3. Physicochemical properties of the studied compounds (EPI Suite™, 2007).
Class of compound Sub group
Mw
(g mol-1)a log Kowb
Sw (mg L-1)c
H (atm·m3 mol-1)d
Metals As, Cd, Co, Cr, Cu, Hg,
Ni, Pb, V, Zn 51 - 207 −0.6 - 0.7 6·104 - 4·105 2·10-2 - 0.8
Esters Phthalates
Adipates OPs
194 - 447 202 - 427 266 - 431
1.7 - 10 2.4 - 10 1.6 - 4.7
1·10-5 - 8·103
4·10-6 - 690 5 - 6·103
4·10-8 - 4·10-5
2·10-6 - 2·10-4
1·10-11 - 3·10-6 Pesticides Biocides 110 - 362 1 - 4.7 7·10-6 - 3·105 6·10-12 - 5·10-7 Insecticides
Herbicides Fungicides
183 - 505 111 - 412 169 - 403
−0.9 - 7.4 −4.5 - 5.3 0.9 - 5.5
2·10-3 - 1·106
5·10-2 - 1·106
4·10-2 - 9·103
3·10-12 - 4·10-4
4·10-19 - 2·10-4
8·10-14 - 3·10-5
Hydrocarbons PAHs
Terpene (Limonene) 202 - 276 136
4.9 - 6.7 4.8
2·10-4 - 9·10-2
44 1·10-7 - 8·10-6
0.4 Phenols Chlorophenols
Butylhydroxytoluene Triclosan 4-Nonylphenol
129 - 266 220 290 220
2.2 - 4.7 5.0 4.7 5.9
45 - 1·104 10 9.3 2.7
1·10-7 - 4·10-7 4·10-6 5·10-9
6·10-6 Organometals Organotin
compounds 177 - 351 0.6 - 7.4 6·10-7 - 4·103 1·10-9 - 1.5
Pharmaceuticals Fluoroquinolones
Tetracyclines 319 - 361 444 - 483
−0.3 - 0.3e
−4 - −0.7 7·103 - 4·104
160 - 3·105 5·10-20 - 9·10-19
1·10-31 - 5·10-24 NSAIDs
Hormones 206 - 296 272 - 298
3.0 - 4.0 2.8 - 4.1
11 - 260 13 - 560
5·10-12 - 2·10-7
1·10-12 - 6·10-10
Siloxanes Methylsiloxanes 162 - 445 4.8 - 6.5 1·10-4 - 1.4 9·10-2 - 0.8 Fluorinated compounds
Perfluorochemicals 314 - 714 2.2 - 12 6·10-7 - 2 1·10-9 - 2·103
Halogenated compounds
Polychlorobenzenes PBDEs I-PCBs WHO-PCBs
PCDD/Fs
147 - 285 407 - 959 258 - 395 292 - 395 306 - 460
3.3 - 5.9 5.9 - 12 5.7 - 8.3 6.3 - 8.3 6.3 - 9.5
0.3 - 100 3·10-6 - 0.3 4·10-4 - 0.1 4·10-4 - 3·10-2
9·10-6 - 3·10-2
9·10-4 - 3·10-3 1·10-8 - 7·10-6
5·10-5 - 2·10-4
5·10-5 - 1·10-4
1·10-6 - 2·10-5
PCAs Depend on the degree of chlorination
Abbreviations can be found in Table 2. aMw: Molecular weight. blog Kow: octanol-water partition coefficient, estimated values. cSw: Water solubility, estimated values. dH: Henry´s Law Constant, estimated values. eExperimentally determined value (Takacs-Novak et al., 1992). Table from Paper III.
2. TARGET COMPOUNDS
16
Figure 2. A selection of the target compounds. Mw, molecular weight (g mol-1); log Kow,
octanol-water partition coefficient; Sw, water solubility (mg L-1); H, Henrys Law Constant
(atm·m3 mol-1) (EPI Suite™, 2007).
Tris(2-chloroethyl) phosphate (TCEP)Mw: 285.49log Kow: 1.63Sw: 5 597H: 2.6 · 10-8
Tris(2-butoxyethyl) phosphate (TBEP)Mw: 398.48log Kow: 3.00Sw: 604H: 1.2 · 10-11
NHN
N
CH3
O
OH
O
F
NorfloxacinMw: 319.34log Kow: -0.31Sw: 40 231H: 8.7 · 10-19
O
OCH3
CH3
O
O CH3
CH3
Di-(2-ethylhexyl) phthalate (DEHP)Mw: 390.57log Kow: 8.39Sw: 1.3 · 10-3
H: 1.2 · 10-5
OBr
Br
Br
Br
Br
Br
Br
Br
Br
Br
PBDE 209Mw: 959.17log Kow: 12.11Sw: 2.6 · 10-6
H: 1.2 · 10-8
OCDFMw: 443.76log Kow: 8.87Sw: 7.6 · 10-5
H: 4.7 · 10-6
Cl
ClCl
OCl
Cl
ClCl
Cl
Cl
Cl
Cl
O
Cl
Cl
Cl
Cl
O
Cl
OCDDMw: 459.76log Kow: 9.50Sw: 9.3 · 10-6
H: 1.1 · 10-6
O
OH
Cl ClCl
Triclosan (TCS)Mw: 289.55log Kow: 4.66Sw: 9.3H: 5.0 · 10-9
OH
Cl
Cl
Cl Cl
Cl
Pentachlorophenol (PCP)Mw: 266.34log Kow: 4.74Sw: 45H: 1.3 · 10-7
Cl Cl
Cl
Cl
Cl
Cl
Hexachlorobenzene (HCBz)Mw: 284.78log Kow: 5.86Sw: 0.3H: 8.9 · 10-4
CH3Si
OSiO
Si
O
Si
O Si
CH3CH3
O
Si
O
CH3
CH3CH3
CH3
CH3
CH3
CH3CH3CH3
Dodecamethylcyclohexasiloxane (D6)Mw: 444.93log Kow: 6.33Sw: 2.1 · 10-3
H: 0.17
S
O
O
O
K
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
Perfluorooctane sulfonate (PFOS)Mw: 538.22log Kow: 4.13Sw: 7.6 · 10-6
H: n.e.
Br
Br
O
Br
Br
PBDE 47Mw: 485.79log Kow: 6.77Sw: 5.4 · 10-2
H: 3.0 · 10-6
Tris(1,3-dichloro-2-propyl) phosphate (TDCPP)Mw: 430.91log Kow: 3.65Sw: 30H: 2.6 · 10-9
O
O
O
CH3
CH3
O
CH3
CH3
Di-iso-nonyl phthalate (DINP)Mw: 418.62log Kow: 9.37Sw: 1.2 · 10-4
H: 2.1 · 10-5
Cl
Cl
Cl
Cl
Cl
PCB 118Mw: 326.44log Kow: 6.98Sw: 7.3 · 10-3
H: 9.2 · 10-5
Cl
Cl
Cl
Cl
PCB 77Mw: 291.99log Kow: 6.34Sw: 3.2 · 10-2
H: 1.3 · 10-4
CH3
Si CH3
CH3O
SiCH3
CH3
O
Si
CH3CH3
OSi
CH3
CH3
OSi
CH3
CH3 CH3
Dodecamethyltetrasiloxane (MD3M)Mw: 384.85log Kow: 6.52Sw: 1.1 · 10-4
H: 0.79
CH3O
O
PO
OO CH3
O O CH3
Cl
O
PO
OCl
O
Cl
ClO
P
O
O
Cl
Cl
OCl
Cl
Cl
2. TARGET COMPOUNDS
17
Sources and use patterns
The contamination load derived from STPs is highly dependent on the patterns
of use of the numerous chemical substances circulating in the technosphere of
the society served by the STPs. Nonpoint source pollution by diffuse dispersion
of pollutants, such as PAHs, PCBs and PCDD/Fs, from diverse sources, via long-
range air transport, land or streets and then through storm water systems and
sewers, continuously contributes to the chemicals contained in sewage.
However, point source pollution, in which the pollution comes from a specific
site (and is easier to control than nonpoint source pollution), may also be
contribute to the chemical content in sewage.
Intended uses of consumer products such as PPCPs readily (and inevitably)
lead to their release to the sewer system, thus the quantities used and sewage
levels are directly linked. Leakage from consumer goods is another source of
chemical substances to STPs. Notably, flame retardants and plasticizers are
slowly emitted from the large stocks of consumer articles and building
materials in the communities served, which may therefore be significant
sources of such chemicals in the sewer system. Consumer products are likely to
be more important emitters (molecular emissions) of volatile than semi-
volatile (higher molecular weight) compounds. For semi-volatile pollutants,
particulate emissions may be more important. Compounds may also be emitted
from consumer products through leaching during washing or cleaning.
Physicochemical characteristics of the contaminants
The characteristics (physicochemical properties) of the sewage contaminants
are, as mentioned earlier, summarized in Table 3 while more detailed
information is given in Table S1 of the Supplementary data for Paper III. In
addition to their use patterns (as outlined above), the physicochemical
properties of pollutants also strongly affect the likelihood that they will reach
STPs, and their behaviour and fate during the sewage treatment process if they
do.
During sewage treatment the compounds may, for instance, evaporate and/or
be degraded. Polar (highly water soluble) compounds and those with low
sludge affinity (low log Kow values) that are not readily biodegradable are likely
to pass through an STP virtually unaffected by the process. The volatility
(tendency of a substance to evaporate, which is negatively correlated with its
2. TARGET COMPOUNDS
18
molecular weight) of a compound may affect both initial emission rates of
additives from consumer products and evaporative losses in the sewage
treatment process. However, during sewage treatment process only the most
volatile OCs appear to be vented away to any great extent.
The compounds’ tendency to be biodegraded during the process will affect
their fate in STPs and, indirectly, the climate at the STPs’ location is also
influential. For example, the water temperature will be lower in STPs located in
the far north than in southerly STPs, hence the biological activity in them
towards biodegradable compounds and their removal efficiency are also likely
to be lower (IVL, 2006a). The generally lower availability of more lipophilic
molecules for biodegradation is another influential factor. Non-polar
compounds (with high logKow and low water solubility values) are likely to
have high affinity for sludge (and thus strong tendencies to sorb to it), in
addition to low biodegradability. Hence, these compounds are generally found
exclusively in sludge.
However, many chemical substances that reach STPs are semi-polar, semi-
volatile or semi-biodegradable and their behaviour during the treatment
process is intermediate compared to the extremes mentioned above. The
complexity of sewage (e.g. its high, but variable, content of organic matter) also
influences, and reduces the predictability of, compounds’ fates and behaviour in
STPs.
19
The municipal STPs considered in this thesis are spread across Sweden, see
Figure 3. In their selection, particular account was taken of their size, load,
technical parameters, proportions of industrial, household and other waste
handled, and geographic locations. The following plants have been investigated:
Stockholm (STP A); Gothenburg (STP B); Umeå (STP C); Eslöv (STP D); Borås
(STP E); Alingsås (STP F); Borlänge (STP G); Floda (STP H); Bollebygd (STP I);
and Bergkvara (STP J). These plants represent large STPs (A, B) serving large
cities, medium-sized STPs (C-G) processing mixed sewage from residential
areas and large industrial sites and/or hospitals and small STPs (H-J) with
negligible industrial loads.
These STPs use conventional sewage treatment methods that include:
mechanical processes (screening and removal of sand and fat); chemical
treatment (flocculation of phosphorus with an agent such as ferrous sulphate
or ferrous chloride); and biological processes (degradation of organic material
by microorganisms and removal of the remaining phosphorus). Solids are
removed from the water by clarifiers as sludge, which is then anaerobically
digested or aerobically stabilized (i.e. organic material is degraded in the
absence or presence of oxygen, respectively) and finally dewatered. However,
almost every STP is unique in terms of its treatment processes, the size of the
human population it serves and the types of associated activities. Descriptive
data of the studied STPs are given in Table 4.
3. SEWAGE TREATMENT PLANTS
20
Figure 3. Locations of the selected Swedish STPs (A-J). STP ID, see Table 4.
Umeå STP (STP C in Figure 3) was the plant considered in Papers I, II and V,
thus its treatment processes are described in more detail below. It is located in
the northern part of Sweden, where the climate is cold, with a yearly average
temperature of 3.4°C. The STP serves a population of almost 100 000 people
(2010), and receives mixed raw sewage (13 Mm3 year-1), mainly consisting of
domestic water (ca. 20% storm water), but also some sewage from industrial
sites and a large hospital.
The treatment processes include: mechanical, chemical (phosphorus
flocculation using ferrous sulphate, FeSO4) and biological treatment. Primary
and secondary clarifiers (handling waste derived from chemical and biological
treatment, respectively) are used for removing solids from the water, as sludge.
Most of the sludge produced in the secondary clarifier is reused to retain and
recycle the microorganisms in the biological treatment. The duration of the
recycling time of this sludge is about three days, and a minor amount is
returned to the influent. The sludge generated during the primary clarification
(i.e. chemical sludge) is then anaerobically digested (retention time, 18 days)
together with external sludge from the municipality’s other STPs (of the total
FHB
IG
DJ
A
G
C
N
3. SEWAGE TREATMENT PLANTS
21
ca. 2 300 tonnes d.w. year-1 sludge produced, ca. 17% is derived from external
sources). After digestion polymer is added then the sludge is dewatered (by
centrifugation) to a d.w. of 31%. A schematic diagram of the treatment process
can be seen in Figure 4, which also shows residence times throughout the plant.
Figure 4. Schematic diagram (modified from Papers I and II) of the sewage treatment process in Umeå STP, including residence times throughout the plant and the sampling locations used in the studies described in Papers I and II.
10 h
20 min
2.5 h
Sand/fat
removal
Screen Pre
aeration
Primary
clarifier
Activated sludge
treatment
Secondary
clarifier
Thickener
Anaerobic
digester
Sludge
siloDewaterer
Dewatered (digested) sludge
PelletThin layer
drier
Moving belt
drier
Final effluent
Raw sewage water
Sampling location
FeSO4
External sludge
18 days
Polymer
Aerated effluent
Primary effluent
30 min 45 min 1.5 h 1.8 h 3.6 h
Raw sludge
Digested sludge
Sludge, primary clarification
Sludge, secondary clarification18 h
A B C D
E F
G
H
I
J
K
A
B
C
D
E
F
G
H
I
J
K
Table 4. Descriptive data for the selected Swedish sewage treatment plants (STPs, 2010).
Stockholm Gothenburg Umeå Eslöv Borås Alingsås Borlänge Flodaa Bollebygd Bergkvara
STP ID A B C D E F G H I J
No. of personal equivalents (pe)
656 000 640 000 129 000 74 000 73 000 27 000 25 000 6 000 3 700 2 500
Inhabitants served 737 000 649 000 92 000 20 000 82 000 26 000 44 000 10 000 4 100 5 900
Dimensioning of the STP (pe) 900 000 680 000 116 000 330 000 110 000 60 000 60 000 13 000 6 000 6 500
Type of activity connectedb Ind. (mix) Ind. (mix) H Ind. (F) H/Ind. (T, C) Ind. (L) H House House House
Treatment of the sewagec M/C/B/D M/C/B/D M/C/B/D M/B/C/D M/C/B/D M/C/B/D M/C/B/D M/C/B/S M/B/C/S M/B/C/S
Solid tr (days)d 19 15 18 30 25 17 15 -- -- --
Raw sewage water
(Mm3 year-1)
89 119 13 3.7 13 3.2 5.6 1.5 0.24 0.6
Storm water (%) 5 57 20 28 50 24 35 66 21 46
Sewage sludge
(tonnes d.w. year-1)
14 400 13 300 2 300 1 100 2 400 690 1 200 270 78 110
Fraction of total production (%)e
6.0 5.5 1.0 0.46 1.0 0.29 0.5 0.11 0.033 0.046
Sewage sludge d.w. (%) 27 30 31 18 21 23 35 30 2.4 17 aFloda STP (2005). bInd., industry; mix, mixture of industrial sewage; F, food; H, hospital; T, textile; C, chemical; L, laundry; and House, household. cM, mechanical; C, chemical; B, biological treatment (activated sludge); D, digestion (anaerobic); and S, stabilization (aerobic) of the sludge. dSolid retention time in the digester. ePercentage of the total annual production of sewage sludge in Sweden (240 000 tonnes d.w. per year; Swedish EPA, 2007). Table from Paper IV.
23
Sampling
General overview
General overviews of the sampling strategies applied in the studies underlying
this thesis (Papers I-V) are presented below, while additional, more detailed
information is provided in the respective papers. The sampling campaigns were
carried out during periods of normal working and weather conditions. Further,
samples were taken in the middle of the week to minimize effects of the
reductions in many industrial activities that occur during weekends and other
weekend activities that may affect sewage water and sludge contents. All
samples were collected in dark pre-treated bottles (extensively cleaned and
treated at 550°C overnight, unless otherwise stated) and, in order to reduce the
risk of microbial degradation, immediately stored at 4°C (water) or -18°C
(sludge) until chemical analysis.
Annual sampling of sewage sludge
One of the objectives of the studies was to obtain samples from selected STPs
annually to explore temporal trends in pollutant loads (see Chapter 1). Sweden
has a temperate climate with daily average January temperatures varying from
0°C in the south to -15°C in the north, but temperatures are generally more
uniform from late spring to autumn. Therefore, composite dewatered digested
(anaerobic) or stabilized (aerobic) sludge samples (n=3, grab-sampled) from
each selected STP were collected annually in September/October when the
temperature at all sampling locations is similar (average, 10°C) to maximize the
comparability of the samples (Papers III and IV). Further, in spring the
frequency of flooding events is high, and during the summer holiday period
patterns of socio-economic activities change markedly. Thus, autumn appeared
4. SAMPLE COLLECTION AND CHEMICAL ANALYSIS
24
to be the optimal time for obtaining reliable data (in terms of effects of
household and industrial uses of anthropogenic substances).
Sampling of sewage water, solids and sludge at Umeå STP
For detailed analysis of the waste streams and effects of STP processes on
selected pollutants, both influent and effluent sewage water (Papers I and V)
were gathered at Umeå STP as flow-proportional samples (24-hours) using the
plant’s existing automatic sampler. To obtain sufficient total sample volumes
for the mass balance analysis reported in Paper II, grab samples of the water
and solid (sludge) phases were collected throughout the STP, according to
residence times in the respective processes (Papers I and II). The sampling
locations used in these studies were designated A-K, of which all were used in
the first study (Paper I) while A, D, E and J were used in the second study
(Paper II), and are schematically displayed in Figure 4. These sampling points
were selected to be able to analyse in detail the distribution of the target
compounds within the STP’s process streams, but due to the more extensive
study presented in Paper I selected locations throughout the process were
used.
Chemical analysis
Environmental samples, in general, can be categorized as complex matrices that
require careful preparation, extraction, clean-up and instrumental analysis. The
complexity of sewage water and sewage sludge is largely due to their high
organic matter contents, and thus high levels of non-target compounds, arising
from soil and diverse other sources, both environmental and anthropogenic.
The analysis of trace contaminants in environmental samples is possible today
due to recent enhancements of instrumental techniques allowing their
detection at pg-fg levels. Highly selective analytical procedures are also
required in order to avoid interferences from non-target compounds (biogenic
and anthropogenic) present in the samples in orders of magnitude higher
concentrations. Therefore, rigorous pre-treatment of sampled matrices to
enrich the target compounds is still often required, and was essential for most
of the chemical analysis of sewage matrices considered here, to obtain as pure
chromatograms as possible and thus avoid false positive identifications and
biased quantifications.
4. SAMPLE COLLECTION AND CHEMICAL ANALYSIS
25
A widely used method for quantifying contaminants in environmental samples
is mass spectrometry (MS), following chromatographic separation, with
internal standard (IS) calibration. In this approach (which was used in most of
the chemical analyses performed in the studies underlying this thesis)
standards are added that are analogous to the target compounds, i.e. have very
similar physicochemical properties, but are assumed to be absent in the
sample. Ideal choices, if available, are isotopologues (differing from analytes
only in isotopic composition, and used in quantification by “isotope-dilution
MS”). If added prior to extraction the IS will allow ready adjustment of the
results to compensate for sources of errors such as losses and matrix effects
during extraction and instrumental analysis. Isotopic labelled standards can
also be used as recovery standards (RS) added prior the instrumental analysis
(which also was used in most of the chemical analyses performed in the studies
underlying this thesis) to calculate the recovery of IS, i.e. the extent of losses
during the experimental work.
The chemical analyses, all based on accredited analytical methods or methods
validated in-house, were performed at qualified Swedish laboratories
experienced in analysis of the target compounds (Papers II-IV). The chemical
analyses of the FQs, OPs, PBDEs, PCAs, PCBz, PCDD/Fs and WHO-PCBs have
been performed by the author of this thesis. Detailed descriptions of the
chemical analyses applied in the studies reported in Papers I and V are
provided in the respective papers. The annual chemical analyses have been
performed at the same laboratories following the same substance-specific
protocols during the seven years of measurements, to ensure adequate
reproducibility (in this respect at least) for time-trend analysis (Paper IV).
General procedure for target analysis of sewage samples
Reliable analytical methods for measuring levels of hazardous compounds, e.g.
in sewage matrices, are needed for qualitative and quantitative analyses, which
provide information about the types of compounds (characterization and
identification) and the amounts of target compounds, respectively, that are
present in a sample. Direct analysis, with minimal or none clean-up, using e.g.
LC-MS/MS or purge-and-trap GC-MS is sometimes possible, while extensive
clean-up (often with several steps) is required for most of the OCs. The
selectivity of the instrument used for detection is highly associated to the use of
clean-up step(s). To provide an overview of the chemical analyses performed in
the studies this thesis is based upon, a general procedure for the preparation
4. SAMPLE COLLECTION AND CHEMICAL ANALYSIS
26
(extraction, clean-up and fractionation) and instrumental analysis of the
sewage samples is given here. The main purpose of this procedure is to remove
co-extracted, interfering compounds while keeping the target compounds
intact in the final extract prior to instrumental detection.
Extraction
The purpose of an extraction is to efficiently extract (using a suitable extraction
solvent) the target compounds from the sample matrix. In this work, the
compounds were extracted using different techniques. In general, solid/liquid
extraction was used for solid samples and liquid/liquid extraction or solid
phase extraction (SPE) for water samples. Soxhlet extraction is a commonly
used extraction technique for POPs in solid matrices (U.S. EPA, 1994c), which
was used in several of the analyses. Pressurized liquid extraction (PLE) is a
modern alternative extraction technique (Richter et al., 1996) that was also
used. Before the sludge samples were subjected for PLE, they were freeze-dried
to achieve complete dryness (d.w. of 100%). SPE is commonly used to enrich
analyte and/or clean-up water samples and was used in some of the analyses.
Clean-up and fractionation
The sample extracts derived from these traditional (non-selective) extraction
techniques require extensive clean-up prior to the instrumental detection. The
purpose of the clean-up is to remove undesirable compounds such as lipids and
other interferences to decrease chemical noise and avoid interfering
compounds co-eluting in the instrumental analysis. Open column absorption
chromatography on sorbents such as silica (neutral or acid/base modified) and
Florisil® are widely used as clean-up for analysis of POPs. In cases when acid
modified silica was not preferable (due to the target compounds sensitivity to
acids), gel permeation chromatography (GPC) was used for macromolecule (e.g.
lipids) removal. In the analysis of PCDD/Fs and PCBs the extract were further
fractionated on activated carbon columns to avoid their interfering in the
instrumental detection due to the higher levels of PCBs present in the samples
than PCDD/Fs.
Instrumental detection and quantification
The prepared and concentrated (less than one mL) sample extracts, are finally
prepared for the instrumental analyses, which were mainly performed using
gas or liquid chromatography (GC or LC) coupled with (high or low resolution)
mass spectrometry (HRMS or LRMS). IS quantification was generally used,
4. SAMPLE COLLECTION AND CHEMICAL ANALYSIS
27
often by isotope-dilution MS, as described earlier. Detailed information about
the analytical techniques applied and the overall analytical uncertainties are
summarized in Table 5.
Quality assurance and quality control
In order to evaluate the quality (accuracy and precision) of the acquired data,
established laboratory quality assurance and quality control (QA/QC)
procedures were used. Method blank samples were run, in parallel to all
samples, as controls (following the same analytical protocols) to ensure that
any contamination during preparation, extraction, clean-up and instrumental
analysis did not significantly influence the quantitative results. The target
compounds were considered to have been positively identified if their
chromatographic retention times corresponded to those of authentic reference
standards and their signal intensities were at least three times higher than the
limit-of-detection (LOD), which was defined as the limit-of-quantification
(LOQ). If the concentrations in the samples were lower than the LOQ values the
results were denoted as <LOQ.
Non-targeted screening using GCxGC-MS
In the study described in Paper V a less discriminatory procedure (fully
described in the paper) than the general protocol outlined above was applied to
sewage water, and the STP influent and effluent was characterized using
comprehensive two-dimensional GC (GCxGC) with time of flight MS (TOFMS)
detection. In GCxGC, two columns with different separation mechanisms are
used to maximize the separation of the target analytes. The material that elutes
from the first dimension (1D), often a non-polar column, is transferred to the
second dimension (2D), often a shorter narrow polar, semi-polar or shape-
selective column. In the non-polar 1D the analytes are separated based on their
volatility while the shorter 2D separates on specific interactions with the
columns’ stationary phase. The higher peak capacities obtained in GCxGC than
in one-dimensional GC is due to its complete separation in two, more or less
orthogonal, dimensions, thus improving the separation both between analytes
and between analytes and sample matrix components. The GCxGC modulator
(the key element of such an instrument) accumulates and focuses fractions
eluting from the 1D and rapidly re-inject them into the 2D.
4. SAMPLE COLLECTION AND CHEMICAL ANALYSIS
28
Data evaluation
General calculations
Single-point IS calibration was generally used as quantification method of the
sewage contaminants. The amount of analyte in sample and recovery of IS were
calculated according to:
m, amount of analyte in sample; Area, peak area; mIS, mass of IS added to the sample prior extraction equivalent to the mass added to the quantification standard.
The sewage sludge concentrations were normalised to their dry weights (d.w.).
Approximately 5 g of the sludge was weighted and put in an oven at 105 C for
24 h. The water content is the difference in mass of the sludge before and after
oven drying.
The STP removal efficiency (RE) – defined as the proportion of a sewage
contaminant (or class of contaminants) eliminated, in total, via mechanical,
chemical and biological treatments in an STP – was calculated according to:
C, total concentration of analyte in effluent or influent water.
Mass flows (MFs, g d-1) of the target compounds were calculated from their
measured concentrations and estimates of mass flows of water and solids
throughout the STP at the sampling time (Papers I and II). Annual
environmental MFs (kg year-1) of the sludge contaminants were calculated from
their measured concentrations (median values) and the total national annual
production of sewage sludge (240 000 tonnes d.w. year-1; Swedish EPA, 2007)
(Papers III and IV).
standardAnalyte,sampleS,I
ISstandardIS,sampleAnalye,
AreaArea
mAreaAream
standardIS,sampleRS,
standardRS,sampleIS,
AreaArea
AreaArea (%) Recovery
totInfluent,
totEffluent,
C
C (%) RE
4. SAMPLE COLLECTION AND CHEMICAL ANALYSIS
29
In the study presented in Paper V, semi-quantification methodology was used
to calculate the sewage contaminant concentrations:
C, concentration of analyte in sample; Area, peak area; mIS, mass of IS added to the sample prior instrumental analysis; VAq, sample, volume of water sample.
Moreover, the breakthrough in the STP (Paper V) – defined as the proportion
of a sewage contaminant not removed, in total, via mechanical, chemical and
biological treatments in the STP – was calculated according to:
C, total concentration of analyte in effluent or influent water.
Time-trend analysis
Log-linear regression analysis was used to determine if there were any
statistically significant time-trends in the sewage sludge concentrations over
the seven study years (Paper IV). The slope generated by this analysis reflects
the yearly percentage change, where a slope of ±10% means continuous annual
change of 10% corresponded to the initial concentration doubling (+) or
halving (-) within seven years. The statistical power was set to 80% (i.e. the
probability of reflecting true trends). Outliers in the data set may have arisen
because of an uncommon change in the physical environment, a change in
pollution load, or errors in the sampling or analytical procedure. Therefore, to
identify such suspected outliers, particular attention was paid to observations
further from the regression line than expected from the residual variance
around the line. Values greater or smaller than 3 times the difference between
the median and the 75th and the 25th percentile, respectively, were considered
outliers. These outliers were, in overall, not included in the statistical
evaluations.
sampleAq,sampleIS,
sampleIS,sampleAnalyte,
VArea
mAreang/LC )(
totInfluent,
totEffluent,
C
CghBreakthrou (%)
4. SAMPLE COLLECTION AND CHEMICAL ANALYSIS
30
Principal Component Analysis
Multivariate statistical techniques, e.g. Principal Component Analysis (PCA), are
commonly used for detecting, extracting and visualizing patterns and trends in
large, complex data sets and thus (inter alia) generating easily interpretable
overviews of experimental results. PCA is a projection technique that reduces
the dimensions of such data sets, by summarizing the information in a reduced
set of orthogonal variables or vectors, known as principal components (PC1,
PC2,…, PCn). These variables can be used to identify similarities and groupings
among the samples and original variables. PCA can also be useful for detecting
suspected outliers and the variables that may influence deviations. PCA results
are presented as scores and loadings, which are superimposable and should be
evaluated together. A score plot illustrates the similarities and differences
between observations (samples) whereas a loading plot illustrates the
underlying reasons (related to contaminant concentrations) for the patterns in
the corresponding score plot. Objects close to each other in the score plot are
closely related while those far apart exhibit larger differences from each other.
PCA (as implemented in the SIMCA-P+11 package, Umetrics, Sweden) was used
in study III (Paper III) to explore the relationships between concentrations of
individual sludge contaminants (or groups of contaminants) and individual
STPs (or groups of STPs). In the last study (Paper V), it was used to detect
suspected outliers in the sewage contaminants data and to find distinct
groupings of sample matrices (clearly separated from each other). In both
studies, the data were mean centered and scaled to unit variance prior to the
PCA to give all parameters equal weighting.
4. SAMPLE COLLECTION AND CHEMICAL ANALYSIS
31
Table 5. Comparative data of the analytical techniques and quantifying uncertainties in the analyses of the compounds.
Class of compound Sub group
Analytical techniquea
Quantifying uncertainty
(%) Reference
Metals As, Cd, Co, Cr, Hg, Ni, Pb
Cu, V, Zn ICP- SFMS ICP- AES
± 20 ± 20-30
[1]b [2]b
Esters Phthalates
Adipates Organophosphorus compounds
GC-MS GC-MS GC-MS
± 20 ± 40 ± 30
CLc [3] [4]c
Pesticides Biocides
Insecticides, herbicides, and fungicides
GC-MS GC-MS
± 40 ± 40
[5] CLc
Hydrocarbons PAHs
Terpene (Limonene) GC-MS ATD-GC-FID
± 30 ± 40
[6]b
[7] Phenols Chlorophenols
Butylhydroxytoluene Triclosan 4-Nonylphenol
GC-MS GC-MS GC-MS GC-MS
± 20 ± 20 ± 20 ± 40
CLb,d CLc,e CLc
CLb
Organometals Organotin compounds ICP-MS ± 6-40 [8]c
Pharmaceuticals Fluoroquinolones
Trimethoprim
Tetracyclines NSAIDs Hormones
LC-MS/MS LC-MS/MS LC-TOF-MS GC-MS LC-TOF-MS
± 40 ± 40 ± 40 ± 40 ± 40
[9]c
[9]c
[10] [10] [10]
Siloxanes Methylsiloxanes ATD-GC-MS ± 40 [11] Fluorinated compounds
Perfluorochemicals LC-MS/MS ± 5-20 [12]f
Halogenated compounds
Polychlorobenzenes PBDEs Indicator-PCBs WHO-PCBs PCDD/Fs Polychlorinated alkanes
GC-MS GC-MS GC-MS GC-HRMS GC-HRMS GC-MS
± 30 ± 30 ± 40 ± 29 ± 29 ± 30
[13]c
[13]c
[6]b
[13]b
[13]b
[14]c,g
aICP, Inductively Coupled Plasma; SFMS, Sector Field Mass Spectrometry; AES, Atomic Emission Spectrometry; GC, Gas Chromatography; MS, Mass Spectrometry; ATD, Automated Thermal Desorption; FID, Flame Ionization Detection; LC, Liquid Chromatography; MS/MS, Tandem Mass Spectrometry; TOF, Time-of-Flight; HRMS, High Resolution Mass Spectrometry. bAccredited analysis. cIn-house validated analytical method. dCL, Commercial Laboratory. eBHT semi-quantitatively analyzed, the results are presented in benzylbenzoate-equivalents. fWith some modifications. gModification: 13C labelled PCB 188 was used as recovery standard instead of ε-HCH.
References: [1] U.S. EPA, 1994b; [2] U.S. EPA, 1994a; [3] IVL, 2005a; [4] Marklund et al., 2005; [5] IVL, 2006b; [6] Swedish EPA, 1990; [7] IVL, 2005b; [8] Kumar et al., 2003; [9] Lindberg et al., 2005; [10] IVL, 2006a; [11] IVL, 2005c; [12] Karrman et al., 2005; [13] Liljelind et al., 2003; [14] Reth et al., 2005.
32
33
The first study (Paper I) focused on the behaviour and fate during sewage
treatment, specifically treatment in the Umeå STP, of several representative
antibiotics – the FQs norfloxacin, ofloxacin and ciprofloxacin, the sulphonamide
sulfamethoxazole and trimethoprim. The sampling points are described in
Figure 4, Chapter 3. In this study the distribution of the analytes within the
STP’s process streams was analysed in detail; samples were taken from the
influent (aqueous and particles) and effluent as well as sludge following each
treatment step. The objectives were to determine concentrations and mass
flows of the target compounds throughout the process, and attempts were
made to predict concentrations and mass flows using consumption data.
In study II (Paper II), the objectives were similar, but the analytes were metals
and OCs (POPs and PPCPs). In addition, the robustness of commonly used STP
fate models for predicting the behaviour and fate of sewage contaminants was
assessed. In both studies, MFs of the target compounds were calculated from
their measured concentrations and estimates of mass flows of water and solids
throughout the STP at the sampling time. The STP removal efficiencies of the
compounds were also estimated, i.e. the levels found in effluent were compared
to levels in influent (aqueous and particles). Finally, an attempt was made to
assess whether the findings could be related to the compounds’
physicochemical properties or biodegradability. The preparation of samples,
calculations and assumptions made are fully described in the respective papers.
To obtain an overview of the general sludge quality in Swedish STPs, the mass
flow of sludge contaminants in them was broadly analysed in the third study
(Paper III). The objective was to perform a screening of metals, POPs, PPCPs
and other OCs in sludge from Swedish STPs with various characteristics
(descriptive data of the STPs are given in Table 3, Paper III). Further, possible
correlations were investigated between sludge contaminant levels and (i)
quantities nationally used and (ii) their physicochemical properties and
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
34
biodegradability in each of the treatment steps. Finally, the distibution patterns
of the contaminants between and within STPs were analyzed and potential
sources of contaminants detected in the sludge were identified. Detailed
information about the analytical techniques applied in these studies (Paper I-
III) is given in Table 5, Chapter 4. In the study presented in Paper III,
environmental mass flows of the sludge contaminants were calculated from
their measured concentrations (median values) and the annual production of
sewage sludge (in Sweden, 240 000 tonnes d.w. year-1; Swedish EPA, 2007),
assuming that all sludge generated is spread on land (a reasonable
approximation, since only small proportions are incinerated). These mass flows
were then compared to the national use statistics (Swedish Chemicals Agency,
2011) to assess the proportions of chemical substances used in the
technosphere that reach the STPs and associate with sludge.
Behaviour and fate of sewage contaminants
Antibiotics
Of the five investigated antibiotics only three (norfloxacin, ciprofloxacin and
trimethoprim) were detected at levels exceeding their LOQ. Trimethoprim was
completely dissolved in the aqueous phase, and its concentration and mass flow
were very similar in both influent and effluent (Figure 5, bottom), suggesting
that it is only marginally affected by the sewage treatment processes at Umeå
STP and is not appreciably sorbed to sludge. The opposite was found for the
FQs; about 80% of their total mass entering Umeå STP was attached to
particles, see Figure 5 (norfloxacin, top and ciprofloxacin, middle), which shows
the mass flows of all three antibiotics in both aqueous and solid phases, and
summarizes their fate during the treatment process. Umeå STP is located in the
northern part of Sweden, where the climate (and thus temperature of the
sewage) is cold. Since the temperature can strongly affect both biotic and
abiotic processes (notably biodegradation and partitioning between phases),
this may at least partly explain the high proportion of the FQs found sorbed to
sludge in influent water (raw sewage); somewhat higher than previously found
in a Swiss STP (33% of the FQs sorbed, sewage temperature 8°C higher; Golet
et al., 2003). The data displayed in Figure 5 also show that removal efficiencies
were high for the FQs (approximately 75% of the total amounts that entered
the STP left it sorbed to digested sludge), but virtually no trimethoprim was
removed. The findings of high removal efficiencies for the FQs are consistent
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
35
with the cited Swiss study. Another Swiss study (Gobel et al., 2005) also
detected trimethoprim solely in aqueous phases, but in contrast to the findings
for Umeå STP levels of trimethoprim significantly decreased during treatment.
Figure 5. Fate of norfloxacin (top), ciprofloxacin (middle) and trimethoprim (bottom) during sewage treatment at Umeå STP. Mass flows, in grams per day, are shown as mean values and standard deviations over three sampling days, except for raw sewage particles. The amounts found in final effluent and digested sludge are expressed in percentages relative to the total amounts (sum in raw sewage water and particles). Theoretically calculated mass flows are shown in italics. From Paper I.
Raw sewage
Norfloxacin
Biological
treatment
Anaerobic
digestion
37±7
Digested sludge
Final effluent41100%
72%
3.4%
Sand/fat removal
Mechanical
and
chemical
treatment
8.7±1
16
3.4±2
8.5
30±13
4.5±0.6
1.7±0.4
Excess sludge
External sludge
1.3±0.2
43±5
Methane
CO2
6
Raw sewage
Ciprofloxacin
Biological
treatment
Anaerobic
digestion
32±2
Digested sludge
Final effluent33100%
77%
3.6%
Sand/fat removal
Mechanical
and
chemical
treatment
6.5±0.2
6
2.9±1
8.7
31±10
5.2±0.5
1.4±0.3
Excess sludge
External sludge
1.9±0.2
56±9
Methane
CO2
24
Raw sewage
Trimethoprim
Biological
treatment Final effluent100% 104%
Mechanical
and
chemical
treatment
41±13 32±10 42±21
Aqueous phase
Solid phase
x±y g/d
x±y g/d
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
36
In the prediction assessments, the predicted environmental concentration
(PEC) and mass flow (PEMF) of each antibiotic were calculated and compared
to the corresponding measured environmental concentration (MEC) and mass
flow (MEMF). The PECs and MECs are presented in Table 4 of Paper I, while
the PEMFs and MEMFs are shown in Figure 6. The concentration predictions
were not completely satisfactory; the correlations between predicted and
measured levels for norfloxacin were very good, but the PECs (and hence mass
flows) were considerably underestimated for trimethoprim and overestimated
for ciprofloxacin.
Figure 6. Mass flows of antibiotics: calculated using national consumption data representing excretion in urine (NPEMF Ref); calculated using data on their consumption within Umeå municipality (MPEMF Ref); and measured in raw sewage water (MEMF RSW). From Paper I.
Other organic compounds and metals
In the metal and OC screening, 75 compounds were initially investigated, but
only 21 (28%) fulfilled defined criteria for further analysis (positive detection
in all six sample matrices). Thus, the following discussion focuses on the
removal efficiency (called the elimination rate in Paper II) and associated
parameters of those 21 analytes. In general, the concentrations reflected the
quantities of the respective substances used in Sweden; sewage levels of some
metals, PPCPs and polymer additives were high, while those of diffusively
emitted halogenated contaminants such as PCDD/Fs, PBDEs and PCBs were
lower. This study also revealed, as expected, that the removal efficiency was
higher for lipophilic than for water soluble compounds. The removal
efficiencies (REs), measured and predicted using the STPWIN module of the
0
5
10
15
20
25
30
35
40
45
Norfloxacin Ciprofloxacin Trimethoprim
g/d
NPEMF Ref
MPEMF Ref
MEMF RSW
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
37
U.S. EPA EPI Suite™ (EPI Suite™, 2007) and percentages adsorbed to sludge (SA)
of the analytes (except for the metals Co, Cu, Ni and Zn) are presented in
Figures 7 and 8, respectively.
The organophosphorus flame retardant and plasticizer (OP) 2-ethylhexyl-
diphenyl phosphate (EHDPP) and tricresyl phosphate (TCP) were found to be
efficiently removed (RE, 81% and 96%, respectively). The remaining aliphatic
OPs seemed to pass straight through the STP, probably due to their high water
solubility. The chlorinated OPs are also highly water soluble and Marklund et al.
(2005) have shown that there is little or no removal of these substances in
STPs, i.e. they generally pass straight through. Most of the pharmaceuticals and
antibacterial agents were also efficiently removed during sewage treatment.
Ciprofloxacin was the only one of three analysed FQs that was detected in all
sampled matrices (RE, 97%, while REs for the other two FQs, norfloxacin and
ofloxacin, were ca. 99%). Triclosan was also highly removed (75%).
Figure 7. Removal efficiencies (%) of the sewage contaminants detected in all matrices sampled at Umeå STP; measured, dark bars, and predicted (using the STPWIN module of the U.S. EPA EPI Suite™ software package), light bars. Abbreviations: DEHP, Di-(2-ethylhexyl) phthalate; TBEP, Tris(2-butoxyethyl) phosphate; TBP, Tributyl phosphate; TDCPP, Tris(1,3-dichloro-2-propyl) phosphate; TPP, Triphenyl phosphate; EHDPP, 2-Ethylhexyldiphenyl phosphate; MBT, Monobutyltin; DBT, Dibutyltin.
0
10
20
30
40
50
60
70
80
90
100
PC
B 7
7
PC
B1
05
PC
B 1
18
PC
B 1
56
PC
B 1
67
PB
DE
47
PB
DE
99
DE
HP
TB
EP
TB
P
TD
CP
P
TPP
EH
DP
P
Cip
rofl
oxa
cin
MB
T
DB
T
Tri
clo
san
%
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
38
To obtain an idea of the contaminants’ sludge adsorption percentage we
assumed that the concentrations of the compounds in primary sludge equalled
their respective concentrations in effluent particles. Further, by using the mass
flow (MF) values, their sludge adsorption (SA, see Figure 8) values were
calculated according to:
Most of the ciprofloxacin and triclosan seemed to sorb to sludge (SA, 78% and
82%, respectively). High adsorption (96%) was also found for DEHP. The
results of this study indicate that several phthalates are degraded during
sewage treatment, as also reported by Roslev et al. (2007) and Dargnat et al.
(2009), who found that approximately 90% of phthalates are degraded in STPs.
Ling et al. (2008) also reported that most of the phthalates are biodegradable in
sludge.
Figure 8. Measured, dark bars, and predicted (using the STPWIN module of the U.S. EPA EPI Suite™ software package), light bars, percentages sorbed to sludge (SA) of contaminants detected in all sampled matrices at Umeå STP. For meanings of abbreviations, see Figure 7. From Paper II.
totEffluent,primaryge,Slud
primaryge,Slud
MFMF
MFSA (%)
0
10
20
30
40
50
60
70
80
90
100
PC
B 7
7
PC
B 1
05
PC
B 1
18
PC
B 1
56
PC
B 1
67
PB
DE
47
PB
DE
99
DE
HP
TB
EP
TB
P
TD
CP
P
TPP
EH
DP
P
Cip
rofl
oxa
cin
MB
T
DB
T
Tri
clo
san
%
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
39
Of six investigated OTCs only two (monobutyltin, MBT, and dibutyltin, DBT)
were detected in all matrices (RE, 41 and 77%, respectively). The metals Co, Cu,
Ni, and Zn appeared to be released into the recipient water in approximately
the same total concentrations (low mg L-1) as they entered the STP (Table S3,
Supporting information for Paper II). In contrast, As, Cd, Cr, Hg and Pb (RE,
92±2%) were detected at similar concentrations in both the solid phase of raw
sewage and sludge. Thus, Co, Cu, Ni and Zn were present in the dissolved phase;
while As, Cd, Cr, Hg and Pb were primarily associated with particles. In general,
the examined substances seem to be unaffected by anaerobic digestion since
their concentrations and MFs were similar before and after the digestion
process.
To facilitate thorough analysis of the behaviour and fate in the STP of the
sewage contaminants (detected in all matrices), their proportions in aqueous
and solid phases of raw sewage, effluent and sludge (normalized to their total
mass flows in raw sewage) were calculated and graphically visualized (Figures
9 and 10). The OP tributyl phosphate (TBP) was almost exclusively dissolved in
the aqueous phase (influent and effluent), EHDPP was mainly sorbed to solid
phases, while the partitioning of the remaining OPs was intermediate. The
detected PCBs appeared to have higher affinity for the solid than the aqueous
phases (influent and effluent). The PBDEs 47 and 99 entered the STP
partitioned approximately equally between aqueous and solid phases, but left,
after sewage treatment, mainly in the solid phase, adsorbed to effluent particles
and sludge.
The OTCs MBT and DBT were highly associated with the aqueous phase of the
STP influent, but were quite evenly distributed between the aqueous and solid
phases after sewage treatment. The four metals, Co, Cu, Ni and Zn, were almost
totally distributed in the aqueous phases (influent and effluent) when passing
through the STP, as mentioned above. No information was obtained on the
distributions of triclosan and DEHP between aqueous and solid phases in raw
sewage, because only their total concentrations were measured. However,
these substances appeared to leave the STP primarily bound to sludge.
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
40
Figure 9. Fractions of the analysed compounds (detected in all sampled matrices) in aqueous (IN H2O) and solid (IN Part) phases of the total mass flows of raw sewage at Umeå STP. For meanings of abbreviations see Figure 7. From Paper II.
0% 20% 40% 60% 80% 100%
Triclosan
TBP
TDCPP
TBEP
TPP
EHDPP
DEHP
Ciprofloxacin
PCB 77
PCB 105
PCB 118
PCB 156
PCB 167
PBDE 47
PBDE 99
MBT
DBT
Co
Cu
Ni
Zn
IN H2O
IN Part
measured as total concentration in raw sew age
measured as total concentration in raw sew age
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
41
Figure 10. Fractions of the analysed compounds (detected in all sampled matrices) in aqueous phase (OUT H2O), solid phase (OUT Part) and dewatered digested sludge (Sludge) of the total mass flows in raw sewage at Umeå STP. Solids in effluent water were only analysed for WHO-PCBs and PBDEs. Asterisked values (*) indicate total concentrations in effluent water, i.e. both aqueous and solid phase. For meanings of abbreviations see Figure 7. From Paper II.
The prediction of removal efficiencies and sludge adsorptions by the STP fate
model designed to predict removal efficiencies and sludge adsorption
percentages provided poor predictions of percentages of polar compounds
sorbed to sludge. Among compounds with similar water solubility, the model
may either grossly under- or over-estimate the fraction sorbed to sludge. The
SA was underestimated for ciprofloxacin, MBT and DBT, possibly due to effects
of polar interactions, such as ion-dipole and hydrogen bond interactions,
between the solutes and sludge. Such interactions are more difficult to predict
0% 20% 40% 60% 80% 100%
Triclosan*
TBP
TDCPP
TBEP
TPP
EHDPP
DEHP*
Ciprofloxacin
PCB 77
PCB 105
PCB 118
PCB 156
PCB 167
PBDE 47
PBDE 99
MBT
DBT
Co
Cu
Ni
Zn
OUT H2O
OUT Part
Sludge
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
42
than others, e.g. dispersive interactions, which are the predominant
intermolecular forces in interactions between lipophilic compounds and sludge.
In contrast, the SA percentages of the water soluble OPs were overestimated,
which is more difficult to explain, but the STPWIN modules were developed
using data for legacy (primarily lipophilic) pollutants, and the physicochemical
properties of the OPs may fall outside the valid model domain. Further studies
are needed to corroborate and explain these findings.
To conclude, the climate at an STP’s location inevitably influences the
temperature of the sewage it treats, and thus the behaviour of chemical
substances during sewage treatment, notably the biodegradation and
distribution of contaminants between water and particulate matter. This may
at least partly explain the inefficient removal of certain polar compounds in the
investigated cold climate STP, which indicates required improvements of the
STP’s processes. Predictions of environmental concentrations and mass flows
of antibiotics, based on consumption data and World Health Organization
(WHO)-defined daily doses (DDD), can provide useful indications of their
environmental loads (Paper I). The STPWIN fate model used in study II (Paper
II) yields total removal efficiencies (RE) and individual values for three
contributing removal processes: biodegradation, sorption to sludge (SA) and
air stripping. Generally, the measured SA-values agreed better than the
corresponding RE-values with the STPWIN estimates.
Swedish sludge quality
The extensive screening reported in Paper III provides information about mass
flows of 282 compounds (in 2004, unless otherwise stated) used in Sweden to
sewage sludge. The total and relative concentrations of the sewage
contaminants (Table 4 and S3, Supplementary data; Paper III) were generally
found to be quite uniform on a d.w. basis, indicating that they largely originate
from broad applications and diffuse dispersion rather than from (industrial)
point sources, even though industries also contribute to chemical constituents
in the sludge. Lower levels of the contaminants (35% lower, on average) were
detected in sludge from STPs processing large quantities of water from food
industries (rich in organic substances and lean in pollutants) or household
sewage (with low levels of industrial pollutants) than in sludge from the other
STPs. In order to obtain an overview of the sludge contaminants we calculated
the median total concentration of each group of compounds detected at each
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
43
STP (Figure 11). The metals were found in the highest total concentrations (five
orders of magnitude higher than those of the least abundant detected analytes:
PCDD/Fs). Similar concentration patterns were also found in study IV (in 2010;
Paper IV), indicating that the sludge quality is quite constant in terms of
contamination levels.
Figure 11. Median total concentrations (logarithmic scale) of each measured group of metals, persistent organic pollutants, pharmaceuticals and personal care products, and other organic contaminants in sludge from sewage treatment plants (STPs) in Sweden. The error bars correspond to the ranges of total concentrations (n=7 STPs, unless otherwise indicated). Abbreviations: PCAs, Polychlorinated alkanes; FQs, Fluoroquinolones; 4-NP, 4-nonylphenol; TCs, Tetracyclines; BHT, Butylhydroxytoluene; OPs, Organophosphorus compounds; PAHs, Polycyclic aromatic hydrocarbons; PBDEs, Polybrominated diphenyl ethers; OTCs, Organotin compounds; NSAIDs, Non-steroid anti-inflammatory drugs; CPs, Chlorophenols; I-PCBs, Indicator-PCBs; PCBz, Polychlorobenzenes; PFCs, Perfluorochemicals; PCDD/Fs, Polychlorinated dibenzo-p-dioxins and -furans. From Paper III.
Pattern of use and mass flows
As mentioned in Chapter 2, the uses of consumer chemicals will affect the
quality of sludge generated in STPs. In order to identify use-related, STP
treatment-related and other factors affecting sludge quality we compared the
quantities used in Sweden and the calculated annual mass flows (MFs) for
sludge (Table 4 in Paper III). Large quantities of metals are used in Sweden,
0
1
2
3
4
5
6
7
Group of compounds
Met
als
Ph
thal
ate
s
PC
As
Silo
xan
esa
Bio
cid
es
FQs
Tric
losa
n
TCsb
Pe
stic
ide
s
BH
T
OP
s
PAH
s
PB
DEs
OTC
s
Lim
on
en
eb
NSA
IDsb
CP
s
Ad
ipat
esb
I-P
CB
s
PC
Bz
PFC
s
WH
O-P
CB
s
PC
DD
/Fs
4-N
P
log
Co
nc.
(µg
kg-1
d.w
.)
a n = 3 STPsb n = 2 STPs
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
44
and this was reflected in high environmental MF (190 tonnes year-1). Other
abundant groups of compounds (MFs>250 kg year-1) detected were PPCPs, see
Figure 12, which are used in ways that inevitably lead to release to the sewer
system. Many of these PPCPs (FQs, tetracyclines, 4-nonylphenol, triclosan and
siloxanes) have high tendencies to sorb to sludge (Buyuksonmez and
Sekeroglu, 2005; IVL, 2005c; Lindberg et al., 2006; Ying and Kookana, 2007).
Figure 12. Percentages of the compounds found (recovered) in the sewage sludge relative to amounts used. For meanings of abbreviations see Figure 11.
High MFs (>10 tonnes year1) were also found for two groups of high volume
plastic additives: phthalates (plasticizers) and PCAs (flame retardants and
plasticizers). These compounds may reach the sewer system through
evaporation from plastics (at low emission rates), partitioning to dust and
cleaning of indoor environments. Plastic materials may make substantial
contributions to levels of phthalates and PCAs in sewage sludge, despite the low
emission rates, due to the large stocks of plastics in Sweden. Other flame
retardants found sorbed to sludge include the PBDEs, which were found in
remarkably high proportions relative to quantities used (like the PCAs); ca. 10-
fold higher than corresponding proportions of phthalates, flame retardants and
plasticizer OPs. All four of these groups of compounds have low volatility (low
emission rates), which makes it difficult to explain the high proportions found
in sludge from their physicochemical properties. However, a contributory
63
51
41
29
17
4.1
3.7
0.9
1
0.4
6
0.2
1
0.1
4
0.1
1
0.0
6
0.0
6
0.0
4
0.0
4
0.0
4
0.0
4
0.0
1
0.0
02
0
10
20
30
40
50
60
70
FQs
TC
s
4-N
P
Tri
clo
san
Silo
xan
es
PC
As
PB
DE
s
Me
tals
Lim
on
e
Bio
cid
es
BH
T
PC
Bz
Pe
stic
ide
s
OP
s
Ph
tha
late
s
OTC
s
NSA
IDs
PFC
s
PA
Hs
Ad
ipat
es
%
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
45
factor may be the limitation of the product register (described in Chapter 2).
PCAs and PBDEs probably enter the country as unrecorded additives in
imported textiles, plastics, computer and other electronic goods etc., thus the
recorded quantities are probably much lower than the amounts present in the
Swedish technosphere. The remaining compounds, detected in the sludge in
relatively low concentrations (Figure 11), stem from multiple, often diffuse
sources, such as traffic and long-range air transport, reaching the STPs via
storm water systems, hence comparisons with use statistics for them is not
meaningful.
Factors affecting mass flows
In addition to pollution loads at STPs several other factors (mentioned in
Chapter 2) affect the concentrations of contaminants in sewage sludge,
including their tendencies to evaporate or be biodegraded during the treatment
process, water solubility and sludge affinity (e.g. if they have very low affinity
they are likely to pass straight through a STP). Therefore, the physicochemical
properties of the compounds and their biodegradability must be considered to
understand the findings and draw conclusions regarding the sludge
contaminants’ behaviour in STPs.
Evaporation
The intrinsic volatility of chemical substances may influence their mass flows at
several life-cycle stages, notably it may strongly affect initial emission rates of
additives in consumer products and losses caused by evaporation in STPs. To
assess possible effects of contaminants’ volatility on their mass flows we
investigated the relationship between the molecular weights of plastic
additives and percentages recovered in sludge, and found a linear relationship
(Figure 13). Thus, evaporation in the STPs may affect their mass flows more
than their molecular emission rates from articles. However, the pattern may
also be due to other factors, such as high water solubility that may cause
contaminants such as OPs that have relatively high water solubility (>5mg L-1)
to pass STPs, as described below. It is also generally accepted that compounds
with high molecule weight (and hence low vapour pressures: Henry´s law
constant <10-5 atm m3 mol-1) e.g. PBDE 209 are primarily released through
particulate emissions; and such wear particles (if they reach the STP) will then
end up in sludge.
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
46
Figure 13. Molecular weight (Mw g mol-1
) vs. percentage recovered (%) in sludge of plastic additives (plasticizers and/or flame retardants), R
2=0.94 (TCPP excluded). OPs, organo-
phosphorus compounds (TBP, tributyl phosphate; TCEP, tris(2-chloroethyl) phosphate; TPP, triphenyl phosphate; TCPP, tris(2-chloroisopropyl) phosphate; TDCPP, tris(1,3-dichloro-2-propyl) phosphate); DEHA, di-(2-ethylhexyl) adipate; Phthalates (DEHP, di-(2-ethylhexyl) phthalate; DINP, di-iso-nonyl phthalate; DIDP, di-iso-decyl phthalate); PBDE #209, decabrominated diphenyl ether. From Paper III.
However, evidence of considerable evaporative losses in STPs was found for
cyclic methylsiloxanes. The proportion of their quantities used that reach STPs
and sorb to sludge seems to strongly depend on their vapour pressure, which
decreases with the number of siloxane units. Proportions of octa- (D4), deca-
(D5) and dodeca-methylcyclotetrasiloxane (D6) recovered were 1.3%, 17% and
54%, respectively. The losses may occur either during biological sewage
treatment or sludge digestion. The latter process is known to result in tainted
biogas that causes deposits in boilers fed such fuel (Dewil et al., 2006; 2007).
Similarly, volatilization is probably the reason for the relatively low recovery of
limonene.
Biodegradation
The recovery of the non-steroid anti-inflammatory drugs (NSAIDs) was low
(unlike that of the other PPCPs), possibly because they completely dissolve in
aqueous phases and thus may be readily biodegraded and/or pass straight
though the STPs. However, the latter explanation conflicts with the relatively
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
200 300 400 500 600 700 800 900 1000
Re
cove
red
(%)
Mw (g mol-1)
OPs Phthalates
Re
cove
red
(%) P
BD
E # 20
9
PBDE # 209
TCPP
TBPTCEP
TPP
TBEP
DEHP
DINP
DIDP
DEHA
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
47
high recovery of FQ antibiotics, which are also quite water soluble. Further, a
recent study found that removal efficiencies of NSAIDs vary considerably
among Swedish STPs, from moderate (32% for diclofenac,) to high (65-90% for
ibuprofen, naproxene and ketoprofen) (IVL, 2006a). The cited study also
concluded that the removal efficiency tends to be lower in STPs located in the
northern part of Sweden, possibly due to the lower water temperatures (and
lower biological activity).
Regarding the OPs, biodegradation may also be responsible for the low
observed recovery of TBP in sludge (Figure 13). Compared to tris(2-
chloroisopropyl) phosphate (TCPP), TBP should theoretically sorb strongly to
sludge due to its lower water solubility, but its recovery in sludge was 10-fold
lower. However, TBP and other aliphatic OPs are known to be more degradable
than aromatic OPs (e.g. triphenyl phosphate, TPP), and chlorinated OPs (e.g.
TCPP) are most persistent (Saeger et al., 1979; WHO, 1991a; 1991b; 1998).
Water solubility
Much lower percentages of OPs, relative to their national use, were found in the
sludge than of PCAs and PBDEs, although they have similar applications. This
may be partially due to recent substitution of the latter by OPs, which will have
immediately influenced the use statistics, but only slowly affect the levels in
sludge (due to their long lifetimes and large stocks in use). However, OPs also
generally have higher water solubility (and biodegradability) than PBDEs,
hence larger proportions of OPs may be degraded or pass straight through
STPs. Chlorinated OPs such as tris(2-chloroethyl) phosphate (TCEP) and TPP
are both persistent and water soluble, and have been shown to pass through
STPs to a great extent (Marklund et al., 2005).
Point sources
As mentioned in Chapter 4, the multivariate data analysis technique PCA was
used to obtain an overview of the relationships between concentrations of
compounds (or group of compounds) in the sampled matrices and the STPs.
The model generated only includes the contaminants that were detected in all
seven selected STPs and concentrations below the LOQ were set to half LOQ.
The results (Figure 14a) indicate that all of the STPs except STP E have similar
contaminant profiles, since they cluster near the origin of the score plot. Among
these STPs, two groupings can be seen, indicating that STPs C and G generate
sludge with lower overall contaminant levels than the others. The
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
48
corresponding loading plots (Figure 14b-e) reflect the underlying reasons for
the trends, and thus provide important indications of the factors influencing the
distribution patterns in the score plot. Sludge from STP E seems to have had
higher proportions of most PFCs (Figure 14b), various pesticides (Figure 14c),
hexachlorobenzene (HCBz), highly chlorinated PCDD/Fs (Figure 14d), 4-
nonylphenol (4-NP) and PBDE 209 (Figure 14e), possibly because textile
factories (in which PFCs may be used during their manufacturing processes, or
present in imported material they use) are connected to STP E. The presence of
highly chlorinated PCDD/Fs in the sludge may be related to use of
pentachlorophenol as a fungicide, e.g. during the storage or transport of fabrics.
This is in agreement with a study by (Hedman et al., 2007), who concluded that
the textile fraction of municipal solid waste contains high percentages of total
PCDD/Fs. However, it should be noted that the Swedish textile industry is no
longer using perfluoroalkylsulfonates (perfluorooctane sulfonate, PFOS;
perfluorodecane sulfonate, PFDS; and perfluorohexane sulfonate, PFHxS)
during manufacturing. An associated finding was that sludge from STP E
contains similar levels of PFOS as the other STPs. In fact, more perfluoro-
alkylsulfonates were found in sludge from the two largest STPs (A and B) and
STP D, than from STP E. Based on these findings, my colleagues and I are
inferred that the primary current source of PFCs in sewage sludge is their
(unrecorded) content in imported articles. Moreover, high usage of sports and
functional clothing (often containing PFCs/antibacterial agents) in the cities
these STPs serve may also contribute to elevated levels of these compounds in
their sludge.
In addition to the high levels of perfluoroalkylsulfonates in sludge from STPs A,
B, and D, they also contain large proportions of metals, antibacterial agents
(triclosan and OTCs) and two phthalates (DEHP and di-iso-nonyl phthalate,
DINP, used as plasticizers in PVC). One can only speculate why high levels of
these compounds were found in the sludge from these STPs, but they are all
located in rapidly growing cities, thus high traffic intensity and newly
constructed buildings may be reasons for the high levels of metals and
phthalates. The elevated levels of zinc and lead may stem from brake linings of
motor vehicles (Hjortenkrans et al., 2007) and metal plated roofs, and the
phthalates from building materials. Although DEHP has mainly been
substituted by DINP since early 2000 (Petersson Lars, 2004) relatively high
levels (mg kg-1 d.w.) were found in the sludge, possibly at least partly due to the
large amounts of the chemical in the technosphere, and hence considerable
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
49
time-lag between its substitution and observable changes in sewage levels.
Industrial production of vinyl flooring was identified as a possible contributor
to the elevated levels of DEHP in STP D.
The lowest levels of sludge contaminants generally were found in the two STPs
C and G, but relatively high proportions of the fungicide propiconazole, which is
primarily applied to barley crops. These findings can probably be related to the
situation of these STPs in agricultural areas. A possible contributor to the
propiconazole found in sludge from STP C may also be a major food-processing
plant in its vicinity.
To conclude, although quite similar levels and distribution patterns of
contaminants were found among the investigated STPs, some minor variations
were detected using a multivariate approach (PCA), notably in the distribution
patterns of PFC in sludge, which could be related to textile industries (STP E),
and the presence of propiconazole in sludge associated with agricultural
activities (STPs C and G). In general, concentrations and distribution patterns of
sludge contaminants in Swedish STPs seem to be independent of the location,
size and treatment techniques applied in the plants, or the types of human
activities that affect the waste streams they handle. Some (weak) correlations
were found between the national use statistics and levels of the contaminants
in sewage sludge.
5. STP REMOVAL EFFICIENCY AND SLUDGE QUALITY
50
Figure 14. Principal Component Analysis (PCA) plots displaying patterns in levels of contaminants in sewage at the selected STPs, based on measured concentrations of the compounds analysed in all STPs (n=7), with levels below the limit-of-detection, LoD, were set to half the LoD. The first and second principal components (PC1 and PC2) explained 34% and 21%, respectively, of the total variance in the data. a: score plot showing relationships between the Swedish sewage treatment plants (STPs). b-e: loading plots showing the corresponding relationships among the metals, persistent organic pollutants (POPs), pharmaceuticals and personal care products (PPCPs) and other organic contaminants. For compound abbreviations, see Table S1, Supplementary data of Paper III. The three congested areas (boxes with broken lines) include: PFDoA, PFOA, PFDA, PFUnA, PFNA, PFTrDA, PFTeDA, PFHpA (panel b); ETPARAB, BUPARAB, BEPARAB, RESORCINOL, PROPARAB (panel c); and 1234789-CDD, 1234678-CDF, 123678-CDD, 2378-CDF, MCCP, OCDF, 14CBz, HCBz (panel d). From Paper III.
-0.2
-0.1
0.0
0.1
0.2
As
Cd
Co
Cr
Cu
HgNiPb
V
Zn
DEP
DBP
BBP
DEHP
DNOP
DIDP
DINP
2MERCAPTOB
KLORKRESOL
DDMAC
PROPICONA
RESORCINOL
MEPARAB
ETPARAB
PROPARABBUPARABBEPARAB
PAHsum
-0.2
-0.1
0.0
0.1
0.2
123478-CDD
123678-CDD
1234789-CDD
OCDD
2378-CDF
234678-CDF
1234678-CDF
1234789-CDF
OCDFPCB 77
PCB 126PCB 169
PCB 105PCB 118
PCB 156
PCB 15714CBz
12CBz
124CBz1235+1245CBz1234CBz
PCBz
HCBz
SCCP
MCCPLCCPPCB7
-0.2
-0.1
0.0
0.1
0.2
MBT
DBT
TBT
Nor
OflCip
BHT
2-CP26-CP
24+25-CPPCP
TCS
TBP
TCEPTCPP
TDCPP
TBEP
TPP
PBDE 28
PBDE 47
PBDE 99PBDE 153 PBDE 154
PBDE 183
PBDE 209
4NP
A: Stockholm – large, industry (mix)
B: Gothenburg – large, industry (mix)
C: Eslöv – industry (food)
D: Umeå – hospital
E: Borås – hospital/industry (textile, chemical)
F: Alingsås – industry (laundry)
G: Floda – household
PC1
PC
2
a)
-0.15 -0.10-0.20 0.10 0.200.150.05-0.05 0
b)
c)
PC1
PC
2
-0.15 -0.10-0.20 0.10 0.200.150.05-0.05 0
PC
2
PC1
d)
PC
2-0.15 -0.10-0.20 0.10 0.200.150.05-0.05 0
PC1
e)
-0.15 -0.10-0.20 0.10 0.200.150.05-0.05 0
PC
2
PC1
23478CDF
123CBz
&DMP
51
-
Several reviews have compiled global monitoring data of sludge contaminants
during the last decade (Clarke and Smith, 2011; Harrison et al., 2006; Law et al.,
2006; Xia et al., 2005). As mentioned earlier, in this time-frame the Swedish
EPA started a program to systematically sample, analyse and archive sewage
sludge. Germany and Switzerland have also started to discuss a routine
program for monitoring and archiving sludge samples and STP effluents (Rudel
et al., 2010). However, to our knowledge, no systematic studies of temporal
trends of extensive sets of sludge contaminants have been previously
published. Therefore, in study IV (Paper IV), time-trends of levels of metals,
POPs, PPCPs and other OCs, in Swedish STPs based on seven years of
measurements, were analysed. Descriptive data of the STPs and the analytical
techniques applied are presented in Table 4 (Chapter 3) and Table 5 (Chapter
4), respectively. Although a seven-year sampling period may be too short for
robust analysis, it should be sufficient to at least indicate directions of potential
trends.
Major aims of this study were to determine if the within-year variability in
contaminant concentrations in sludge samples from Swedish STPs was
sufficiently low to allow time-trend studies over reasonable time-spans and to
(if so) identify statistically significant temporal trends in concentrations of the
investigated sludge contaminants. Any established time-trends were
considered in relation to official attempts to reduce the quantities of harmful
substances released into the environment (e.g. by reducing use of regulated or
questioned chemical substances in both industrial applications and household
articles). Use statistics of the target compounds were retrieved from the
product register (Swedish Chemicals Agency, 2011). A further aim was to
evaluate if these attempts have been successful, by seeking discernible trends
in sewage levels of substances that have recently been substituted by others.
Identification and characterisation of such time-trends may facilitate the design
of future Swedish environmental sludge monitoring programs, in terms of
6. TIME-TREND ANALYSIS
52
variables such as the number of STPs to monitor, sampling frequency, phased-
out (and phased-in) substances to monitor, etc.
Mass flows and time-trends
Environmental mass flows of sludge contaminants
Of 126 compounds that have been analysed annually during these seven years,
only 77 fulfilled the defined criteria (presented in Paper IV, along with an
extensive description of the statistical data evaluation). Annual quantities used
nationally in Sweden and estimated overall mass flows of the 77 contaminants
are given in Tables 1 and 3 (Paper IV), respectively. Statistical evaluation of the
final data set detected significant time-trends for 18 sludge contaminants, 23%
of the compounds fulfilling the criteria, representing almost all compound
groups, with only one or a few significant compounds in each group. The annual
national mass flows were calculated, based on median concentrations of the
sludge contaminants from nine STPs in 2010 and the total national annual
production of sewage sludge (in Sweden, 240 000 tonnes d.w. year-1; Swedish
EPA, 2007). The results clearly show that there are very large differences in
environmental mass flows among the various classes of sludge contaminants,
metals (220 000 kg d.w. per year-1) and PCDD/Fs (0.16 kg d.w. year-1) being the
most and least abundant, respectively (Table 3 in Paper IV).
Variability in sludge contaminant concentrations
In order to assess the feasibility of monitoring contaminants in sewage sludge
for time-trend analysis and tracking emissions of chemical substances
circulating in the technosphere, the variability of the sludge contaminant levels
was evaluated. It was estimated that it would take 5 to 26 years to track an
annual change of 10% with a power of 80% (the probability to reveal true
trends) for the compounds, see Table 4 in Paper IV. The variability was lowest
for the OCs analysed using isotope-dilution MS (as described in Chapter 4) and
the metal cobalt. However, for many of the significant sludge contaminants it
would be possible to detect a 10% concentration change over the time-interval
of seven years, see Figure 15, since the diverse chemical contents of the sewage
matrices were less variable than may have been expected, given their
complexity and the large number of influential variables. In conclusion, the
6. TIME-TREND ANALYSIS
53
results indicate that sewage sludge is a promising matrix for time-trend
analysis.
Figure 15. Estimated number of years required for detecting, with a statistical power of 80%, annual 10% changes in levels of the following substances in STP streams: TDCPP, Tris(1,3-dichloro-2-propyl) phosphate; TBEP, Tris(2-butoxyethyl) phosphate; PFDoDA, Perfluoro-dodecane acid; PFOSA, Perfluorooctane sulfonamide; 124CBz, 1,2,4-trichlorobenzene; 14CBz, 1,4-dichlorobenzene; MBT, Monobutyltin; DBT, Dibutyltin; MCCP, medium chain chlorinated paraffins; MD2M, Decamethyltetrasiloxane; MD3M, Dodecamethyltetrasiloxane; MDM, Octamethyltrisiloxane. *Compounds that showed significant time-trends prior to elimination of suspected outliers.
Statistically significant time-trends
Eighteen of the 77 compounds analysed exhibited significant time-trends, and a
further seven in the original regression analysis, i.e. prior to elimination of
suspected outliers. The analysed compounds are all listed in Table 3 in Paper
IV; the 18 showing significant time trends highlighted in bold, and the seven
additional compounds marked with an asterisk.
Most of the contaminants showing significant time-trends (75%) decreased
annually by 5-65% during the study years, whereas increases of 13-56% per
year were estimated for the others (Table 4 in Paper IV). To prevent the
development or spread of resistance to antibiotic, e.g. FQs, their use should be
balanced and they should not be over-prescribed. This precaution should result
in their levels decreasing in sewage sludge and other environmental matrices.
26
1918
17 17 1716
15
12 12 1211 11 11
109 9 9 9
8 8 8
6 65
0
5
10
15
20
25
30
TD
CP
P*
Tri
clo
san
TB
EP*
PFD
oD
A*
PFO
SA
12
4CB
z
14
CB
z
PB
DE
99*
Cip
rofl
oxa
cin
*
No
rflo
xaci
n
PB
DE
183
MB
T
DB
T
23
78-T
CD
F*
12
346
78-
Hp
CD
D
MC
CP
*
MD
2M
MD
3M
PB
DE
209
OC
DD
12
346
78-
Hp
CD
F
OC
DF
MD
M
PB
DE
154
Co
ba
lt
year
6. TIME-TREND ANALYSIS
54
The levels of the FQs norfloxacin (Figure 16a) and ciprofloxacin in sludge
(2004-2010) decreased annually by 60% and 20%, respectively, correlating
well with declines in national prescriptions of these antibiotics of ca. 90% and
20%, respectively (Swedish MPA, 2011). Triclosan, which is frequently used as
an antibacterial agent in personal care products, has gained public attention
due to its negative environmental impact (Crofton et al., 2007; Veldhoen et al.,
2006), which should also lead to reductions in its sludge levels. The national
use of triclosan declined during the studied years by about 30% and this was
reflected in an annual 65% decline of the triclosan concentration in the sludge
(Figure 16b).
However, increases in levels of about 30% per year were detected for the linear
methylsiloxanes, in line with the national use of siloxanes more than doubling
during these years. Figure 16c shows the time-trend of decamethyl-
tetrasiloxane (MD2M) levels.
The OTCs MBT (Figure 16d) and DBT, the PFCs perfluorododecane acid
(PFDoDA) and perfluorooctane sulfonamide (PFOSA), the PBDEs 99, 154
(Figure 16e) and 183, 1,2,4-trichlorobenzene (124CBz, Figure 16g) and highly
chlorinated PCDD/Fs (OCDD, Figure 16h) all exhibit a significant downward
trend over time. Due to the limitations of the product register for these
compounds, i.e. its failure to track amounts present in imported goods, their
levels in sewage have not been compared with the quantities used annually.
6. TIME-TREND ANALYSIS
55
Figure 16. Significant detected time-trends in levels of the monitored sludge contaminants (2004-2010), a) Norfloxacin; b) Triclosan; c) MD2M, Decamethyltetrasiloxane; d) MBT, Monobutyltin; e) PBDE 154; f) PBDE 209; g) 124CBz, 1,2,4-trichlorobenzene; and h) OCDD, Octachlorodibenzo-p-dioxin. From Paper IV.
c) MD2M
0
25
50
75
100
125
150
175
05 07 09
a) Norfloxacin
0
1000
2000
3000
4000
5000
6000
05 07 09
b) Triclosan
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
05 07 09
d) MBT
0
50
100
150
200
250
300
05 07 09
e) PBDE 154
0
1
2
3
4
5
05 07 09
f) PBDE 209
0
100
200
300
400
500
600
700
05 07 09
g) 124CBz
0
50
100
150
200
05 07 09
h) OCDD
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
05 07 09
Year
Co
nc
. µ
g k
g-1
d.w
.
6. TIME-TREND ANALYSIS
56
However, both highly chlorinated PCDD/Fs and 124CBz are listed in the
Stockholm Convention (UNEP, 2001) and the WFD (EU, 2000), hence their
decreasing trends may be associated with restrictions in their use. PBDEs 99,
154 and 183 have also been classified as POPs under the Stockholm Convention
(since 2009) and, PBDEs 99 and 154 are WFD priority substances. This
classification may have indirectly influenced their downward trends, or
enhance their decline in coming years. Since the global phase-out of PBDEs 154
and 183 (pentaBDE and octaBDE) as flame retardants in plastics they have
been replaced by PBDE 209 (decaBDE), hence unsurprisingly levels of decaBDE
have annually increased by 16%.
However, although use of PBDE 209 (Figure 16f), regulated in the RoHS
directive (EU, 2003), has dropped in national usage by 83% (2004-2008) there
is no clear downward trend in its levels in sludge yet. Medium chain
chlorinated paraffins (MCCP) show the same pattern, with an annual increase
of 13% in sludge levels, but halving of the amount used over the years. The
unexpected uptrends of these flame retardants (PBDE 209 and MCCP) are
probably due to considerable amounts entering the country as additives in
imported goods (textiles, plastics, computers and other electronic goods) that
are not recorded in the product register. A further probable contributory factor
is that many articles treated with flame retardants have long lifetime and large
stocks.
Significant time-trends in sludge levels of the OPs tris(1,3-dichloro-2-propyl)
phosphate (TDCPP) and tris(2-butoxyethyl) phosphate (TBEP), also used as
flame retardants (and plasticizers), only appeared when suspected outliers
were included in the analysis. However, it will be interesting to follow up these
compounds in the future, due to their potential use as substitutes for PBDEs
and the plasticizer DEHP, respectively, when more data are available and hence
the statistical power has increased.
Sludge contaminants with constant levels
Evaluation of the sludge contaminants for which no significant time-trends
were detected is also interesting for assessing whether (legal) regulatory
actions have been effective to date. DEHP, used in the PVC industry, was
classified as a WFD priority substance more than a decade ago (EU, 2000), and
has subsequently been more strictly regulated (EU, 2005). However, although it
has mainly been substituted by DINP since early 2000 (Petersson Lars, 2004;
6. TIME-TREND ANALYSIS
57
Swedish Chemicals Agency, 2007) and the annual quantity used in Sweden
declined by about 40% from 2004 to 2009, no clearly significant time-trend is
apparent in its sludge concentrations as yet (nor for DINP). The constant levels
(mg kg-1 d.w.) of DEHP over the years may be due to the large amounts
remaining in the technosphere and consequent time-lag before concentrations
probably decline in the sewage sludge. In this context it is worth noting that
vinyl flooring has an average lifetime of 20 years. On the other hand, an
indication (albeit not statistically significant) of an increasing trend in DINP
levels can be discerned, the annual median concentration (based on data from
the studied STPs) of DINP in sludge increased by 50% from 2004 to 2010 while
the recorded quantities of DINP increased by about 90% from 2000. Additional
annual measurements are required before significant time-trends can be seen
and hence evaluate if the substitution of DEHP by DINP (in the PVC industry;
DEHP is still used in medical devices) has been successful.
Reported levels of PFOS have been relatively constant in sewage sludge during
the last decade (Clarke and Smith, 2011), despite a manufacturers’ voluntary
phase-out in early 2000. Since 2009, PFOS has been regulated by the Stockholm
Convention (UNEP, 2001), which may affect its future levels in sewage sludge.
However, mass flow studies have shown that degradation of other PFCs to
PFOS may occur during sewage treatment (Bossi et al., 2008; Loganathan et al.,
2007), thus STPs may still continue to release significant amounts of PFOS into
the environment. During the seven study years, the concentrations of PFOS in
the sludge remained quite constant (µg kg-1 d.w.), but are likely to decline in the
future due to the stricter regulations. If no declining trend is observed in the
coming years other PFCs may also need to be more strictly regulated to ensure
that no formation of PFOS occurs through other PFCs.
Levels of the seven monitored metals (except cobalt) also remained constant
(mg kg-1 d.w.) within the investigated time interval and were exclusively
detected below their national limit levels, for materials intended for
agricultural uses (Cd, 2; Cr, 100; Cu, 600; Hg, 2.5; Ni, 50; Pb, 100; Zn, 800 mg kg-
1 d.w.; Ministry of the Environment, 1998). However, median concentrations of
cadmium in the sludge seem to have decreased substantially, by ca. 30% per
year, possibly partly because certified STPs are obliged to limit cadmium to
phosphorus ratios in sludge to 17 mg Cd per kg P (SWWA, 2008) by 2025.
Future regression analyses will reveal if these actions lead to statistically
significant decreases in sludge concentrations.
6. TIME-TREND ANALYSIS
58
Action limits
In Sweden a number of Environmental Objectives jointly encapsulate the
official long-term environmental vision. One, “A Non-Toxic Environment”,
states that, within one generation, the concentrations of non-naturally
occurring substances in the environment will be close to zero and their impacts
on ecosystems will be negligible. In Sweden, and other countries, the work to
reduce emissions upstream STPs are important for minimizing levels of
hazardous substances in the sewage and fulfilling legal environmental
requirements.
“Action limits” are necessary to facilitate identification, and implementation, of
required enhancements, and since no formal limits are currently available we
calculated the 90th percentile (based on the sludge contamination
concentrations in the nine STPs monitored in 2010) for all compounds included
in Figure 15. These action levels can be continuously updated using data
acquired from the annual environmental sludge monitoring program. The
purpose of the limits is to provide professionals with tools to identify
compounds whose concentrations greatly exceed typical levels (in this case for
Swedish sludge). They can then decide if further actions are needed, e.g. to
restrict the emissions from point sources or inform the public about alternative
ways to dispose of harmful substances (rather than flushing them down the
drain).
Systematic elimination and reduction, e.g. by using these calculated “action
limits”, of the largest contributions of contaminants to the sewage sludge will
improve the quality of the sludge. Ideally, such a systematic approach could
lead to sufficient reductions in levels of contaminants in the sludge for both
authorities and the public to accept application of the sludge to agricultural
soils. This would be a big step towards sustainable management of nutrients.
To conclude, significant time trends in sludge levels were detected for
remarkably high proportions (a third) of the compounds examined in this
analysis. The trends for many of the sludge contaminants that showed
significant trends with time followed trends in the quantities used in Sweden,
generally decreasing due to increasingly strict environmental legislation and
regulations. Most of the significant trends were reductions with time, but about
a quarter were increasing trends, and those of the linear methylsiloxanes
followed the same patterns of increase as in the national use quantities.
6. TIME-TREND ANALYSIS
59
However, levels in sewage sludge of various contaminants that have been
substituted and legally restricted showed no significant trends, or only slowly
declined several years later. Time-lags, due to large amounts of chemical
substances remaining in the technosphere, and limitations in the product
register for e.g. phthalates and PBDEs may explain the lack of expected trends.
In the future, when more data are available, it should be possible to judge
whether the substitution of PBDEs and PCAs by OPs or DEHP by DINP has been
effective (provided it is reflected in changes in the sewage sludge).
Regardless of future prospects, the results show that statistical time-trend
analyses can detect significant decreasing or increasing trends in levels of
chemical substances in sewage sludge. The time period applied could be
extended to at least ten years to confirm the significance of detected trends and
potentially detect time-trends for a larger set of compounds. Prolonging the
monitoring campaign and time-trend analysis is also required for evaluating
whether any discernible trends will appear for substances that have recently
been substituted by others that are (hopefully) less toxic to humans and the
environment.
60
61
-
In a previous study, at a French STP (Semard et al., 2008), the feasibility of
using GCxGC-TOFMS for broadly screening hazardous substances in urban
sewage water was investigated. However, the cited study focused on specific
compound groups, especially PPCPs, pesticides and CMRs. The authors
concluded that most of these compounds were removed efficiently by current
STP technology, but that more studies are needed to validate the removal
efficiency of GCxGC-amenable compounds. Therefore, in study V (Paper V), a
broad and unbiased characterization (non-targeted screening) of sewage water
(influent and effluent, in Umeå STP) was performed using comprehensive
GCxGC-TOFMS. The water samples were subjected to minimal preparation
(non-discriminating extraction and clean-up), in order to retain as much
information as possible about their chemical composition, before the
instrumental analysis. The results were then interpreted with the aim to
evaluate the STP removal efficiency (in Chapter 4 general calculations are
described) of structurally diverse organic sewage contaminants, especially
those that were poorly removed. Details of the experimental protocols (sample
treatment and instrumental analysis) and data evaluation are given in Paper V.
An introduction to the GCxGC technique is presented in Chapter 4. In GCxGC
analytes are initially separated on two GC columns, with distinctly different
separation modes (“dimensions”). In this study a non-polar column followed by
a semi-polar/highly polarizable column were used for the first (1D) and second
(2D) dimensions, respectively, which thus primarily separated the compounds
according to their volatility, and polarity or polarizability, respectively.
7. NON-TARGETED SCREENING OF POORLY REMOVED CONTAMINANTS
62
Principal Component Analysis
The results from the PCA, the multivariate analysis technique used for
visualizing patterns in the data and detecting outliers, show distinct grouping
of the replicates of sample matrices (five replicates per sample matrix) and the
four blank samples (one for each sample matrix). Further information
regarding the PCA technique can be found in Chapter 4. As can be seen in
Figure 17, the sample matrices (influent aqueous, effluent aqueous, influent
particles, effluent particles and blank samples) clearly separated from each
other and no suspected outliers were detected.
The first principal component (PC1) reflects differences in concentration,
samples and compounds with the highest concentrations appearing to the left,
whereas the second principal component (PC2) largely reflects differences in
contaminant patterns between aqueous and solid samples. Blank samples have
low concentrations of analytes and a profile that matches those of neither
aqueous nor particle samples, hence they are positioned far to the right along
PC1 and close to the middle of PC2. The loading plot (Figure 17, lower)
illustrates underlying reasons for the patterns in the score plot (Figure x,
upper) and reflects the physicochemical properties of the contaminants, with
compounds having high water solubility, e.g. caffeine and TCEP in the lower
right quadrant. Compounds in the lower right quadrant are likely to have low
removal efficiencies during sewage treatment. In the upper half of the loading
plot non-polar compounds are found, which are expected to sorb to sludge and
hence, have high removal efficiencies.
7. NON-TARGETED SCREENING OF POORLY REMOVED CONTAMINANTS
63
Figure 17. Principal Component Analysis (PCA) plots of the data, 1128 observations (compounds) and 24 variables (sample matrices, i.e. five replicates of each sample matrix and four blank samples). The first and second principal components (PC1 and PC2) explain 41% and 25%, respectively, of the total variance in the data. The score plot, upper, shows the relationships among the samples, with distinct groupings of the sample matrices. The loading plot, lower, shows the corresponding relationship among the compounds. TCEP, Tris(2-chloroethyl) phosphate. From Paper V.
-0.1
0.0
0.1
0.2
0.3
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24 0.26 0.28
PC2
PC1
InAq 1InAq 2
InAq 3
InAq 4InAq 5
InAq Blank
InPart 1
InPart 2InPart 3
InPart 4
InPart 5
InPart Bl
OutAq 1
OutAq 2
OutAq 3
OutAq 4
OutAq 5
OutAq Bl
OutPart 1
OutPart 2
OutPart 3OutPart 4
OutPart 5
OutPart Bl
-8
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-8 -6 -4 -2 0 2 4 6 8 10 12 14
PC2
PC1
Influent particles
Effluent particles
Influent/Effluentaqueous
Blank samples
TCEP
Caffeine
7. NON-TARGETED SCREENING OF POORLY REMOVED CONTAMINANTS
64
Assessment of the STP’s removal efficiency
This study showed that the STP’s overall removal efficiency of GCxGC-amenable
compounds is relatively good, exceeding 70% for most of the 1128
contaminants detected (Figure 18). This non-targeted screening also showed
that the removal efficiencies are correlated both to the first dimension (1D) and
second dimension (2D) retention times of the sewage contaminants. As
expected, compounds with low polarity (low water solubility and strong
affinity to sludge; the compounds with short 2D retention times in Figure 18b,)
were efficiently separated. It is harder to explain the correlation of removal
efficiencies with 1D retention times, because during the biological treatment in
STPs, for instance, volatile compounds may be lost through evaporation, hence
efficient removal would be expected for compounds with short 1D retention
times. In contrast, the opposite relationship was observed, i.e. the
volatilities/2D retention times of the compounds were inversely related to their
removal efficiency. However, the 1D retention times are also related to the
lipophilicity of the contaminants; GCxGC-amenable compounds are generally
semi-volatile and contain at most small numbers of polar functional groups.
Further, the lipophilicity (and 1D retention times) of the sewage contaminants
is strongly, positively correlated with their molecular weight and tendency to
sorb to sludge. In contrast, compounds with higher proportions of polar
functional groups are either not extracted by dichloromethane (the extraction
solvent used) or degraded in the GC inlet.
7. NON-TARGETED SCREENING OF POORLY REMOVED CONTAMINANTS
65
Figure 18. The removal efficiency (%) of sewage contaminants vs. a) volatility (1D), and b)
polarity (2D). The removal efficiencies represent mean values over 2 minutes (
1D) and 0.1 s
(2D), respectively. From Paper V.
2D graphs (bubble plots) were constructed to illustrate the influence of various
physicochemical characteristics of the compounds on the STP treatment
efficiency. These new plots were created because, as mentioned above, single-
dimensional representation (or separation) does not provide sufficient
resolution. These 2D graphs, in which the position of the compounds shows
their retention time and the size of the markers indicates their removal
0
10
20
30
40
50
60
70
80
90
100
10 14 18 22 26 30 34 38 42 46 50 54 58 62 66
Rem
oval
Eff
icie
ncy
(%)
Volatility 1D (minutes)
0
10
20
30
40
50
60
70
80
90
100
0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9
Rem
oval
Eff
icie
ncy
(%)
Polarity 2D (seconds)
a)
b)
7. NON-TARGETED SCREENING OF POORLY REMOVED CONTAMINANTS
66
efficiency, can be seen in Figure 20. Volatile organic compounds (VOCs) have
boiling points below 250°C, according to the EU´s definition (EU, 2004), which
corresponds to about 900 s, or a quarter of the total retention time in 1D. To
summarize the information displayed in the bubble plots; volatile non-polar
compounds appear in the lower left corner, volatile polar compounds in the
upper left, semi-volatile non-polar compounds in the lower right, and semi-
volatile polar compound in the upper right (as schematically shown in Figure
19). However, 2D chromatography occurs under isothermal conditions and the
polar compounds are therefore spread out over a larger area than the non-
polar.
Volatile
Polar
Semi-volatile
Polar
Volatile
Non-polar
Semi-volatile
Non-polar
Figure 19. Schematic representation of positions of contaminants according to their volatility and polarity in the bubble plots (Figure 20).
Data for the total set of 1128 compounds (Figure 20a), clearly show that highly
volatile (far left) and non-polar compounds (lower parts) are removed to a high
degree (as expected) during the sewage treatment process.
In order to find and identify the compounds that are poorly removed by current
STP treatment technology, the compounds with removal efficiencies higher
than 65% were excluded from further analysis. The average removal efficiency
of the groups of efficiently and poorly removed sewage contaminants (thus
defined) was 94% and 22%, respectively. Then a new bubble plot was created
(Figure 20b), that was much less complex and easier to interpret. In this new
plot, the sizes of the bubbles represent the “breakthroughs” in the STP, i.e. the
fractions of the respective sewage contaminants that were not removed. It
indicated that many strongly retained (highly polar or polarizable) compounds
in 2D are poorly removed, i.e. they have large STP breakthroughs. For weakly
retained, lipophilic, compounds that elute at 2D retention times shorter than 0.5
s, higher removal efficiencies are observed, as can also be seen in Figure 18b.
7. NON-TARGETED SCREENING OF POORLY REMOVED CONTAMINANTS
67
Figure 20. Bubble-plots representing a) the removal efficiency (%) of the total data set of 1128 compounds; b) the breakthrough (%) of the same compounds; and c) the breakthrough (%) of the ca. 200 compounds that had a removal efficiency less than 65%. From Paper V.
0.0
0.5
1.0
1.5
2.0
0 500 1000 1500 2000 2500 3000 3500 4000
Volatility 1D (seconds)
Pola
rity
2D (
seco
nds)
0.0
0.5
1.0
1.5
2.0
Pola
rity
2D (
seco
nds)
0.0
0.5
1.0
1.5
2.0Po
lari
ty2D
(se
con
ds)
a)
b)
c)
7. NON-TARGETED SCREENING OF POORLY REMOVED CONTAMINANTS
68
Tentative identification of poorly removed contaminants
A total of 68 compounds were tentatively identified (among the 188
components that had less than 65% removal efficiency) using the NIST library.
The final data set is given in Table 2 in Paper V. An additional bubble plot was
created for this set of compounds, Figure 20c. Effluent concentrations of these
compounds varied between 0.2 and 12 000 ng L-1, 90% of them were found to
be predominantly (>90%) dissolved in the aqueous phase of the effluent, and
60% of them were predominantly dissolved in the aqueous phase of the
influent. These findings were also reflected in the lower removal efficiencies
estimated for these water soluble compounds and most of the tentatively
identified compounds had less than 50% removal efficiency. An interesting
observation was that although 1H-Indole-3-carboxaldehyde was exclusively
attached to particles in both influent and effluent, it was still not efficiently
removed. The presence of 1H-Indole-3-carboxaldehyde in the influent and lack
of its removal may be due to its formation, e.g. from indole, during the
treatment process. Many of the tentatively identified compounds have polar
functional groups (Table 2 in Paper V) that increase their water solubility and
make them more prone to follow the water path through the STP. In addition,
several of the compounds share some common structural features, as
illustrated in Figure 21, which presents the percentage of sewage contaminants
that possess certain functional groups, e.g. 10% of the compounds were
(halogenated) organophosphate esters, structural features that make these
compounds relatively stable and resistant to degradation.
The two amides, carbamazepine (pharmaceutical) and diethyltoluamide (DEET,
insect repellent), were completely dissolved in the aqueous phase (both
influent and effluent) and were not removed at all. The poor removal of
carbamazepine during sewage treatment is consistent with a previous mass
balance study by Nakada et al. (2010) who also concluded that DEET removal
was limited. Notably, carbamazepine concentration was twice as high in the
effluent as in the influent, again in agreement with previous studies (Jelic et al.,
2011; Kim et al., 2007). Thus, in this case too, some formation appears to occur,
e.g. via deconjugation. OPs are a group of compounds that were frequently
detected and insufficiently removed, with a maximum removal efficiency of
33%. Two of the OPs, TBEP and TCEP, were almost completely dissolved in
influent and effluent water (>94%). These findings are also consistent with
reports by Marklund et al. (2005) of at most marginal removal of TBEP and
7. NON-TARGETED SCREENING OF POORLY REMOVED CONTAMINANTS
69
halogenated OPs (TCEP, TCPP and TDCPP) in Swedish STPs with a maximum
(average) removal of 28% for TDCPP.
Figure 21. Percentages of tentatively identified sewage contaminants that share the indicated functional groups and moieties.
Effluent concentrations and sources of poorly removed contaminants
The total effluent (aqueous and particle) concentrations of the 68 tentatively
identified sewage contaminants were calculated (Table 2 in Paper V) to obtain
an overview of their environmental loads from the STP. Effluent concentrations
of selected compounds and the most abundant sources for the tentatively
identified sewage contaminants are given in Figures 22 and 23, respectively.
Large proportions of traffic-related compounds were identified, largely
representing derivative (ketones and quinones) of PAHs and other polycyclic
aromatic compounds. Emissions from vehicles and other combustion sources
are likely sources of these compounds in sewer systems. The most abundant
compound (at levels of 12 µg L-1) was 2,4,7,9-tetramethyl-5-decyn-4,7-diol,
which is used as a defoamer in paint, e.g. for vehicles. Other potentially traffic-
related compounds include the benzothiazoles (used in the rubber industry),
which were the fourth most abundant of the compounds (at 2.2 µg L-1).
68
53
31
1916
10 107
3 3 1.50
10
20
30
40
50
60
70
80
Aro
mat
ic
Ke
to/e
ster
S,N
,O-h
ete
rocy
clic
Aro
mat
ic a
nd
(h
ete
ro)c
yclic
(He
tero
)cyc
lic
(Ha
loge
nat
ed)
org
ano
ph
osp
hat
e e
ste
rs
S/O
-eth
ers
Am
ide
s
Nit
ro
Aci
ds
Am
ine
%
7. NON-TARGETED SCREENING OF POORLY REMOVED CONTAMINANTS
70
Besides traffic-related compounds, large proportions of flame retardants and
plasticizers, food additives and PPCPs were also identified as poorly removed
sewage contaminants (see Figure 23). Among the PPCPs, a large proportion
was additives in cosmetics, e.g. odoriferous substances used as fragrances in
perfumes. The PPCPs found at the highest levels was the UV-blockers
benzophenone and oxybenzone (930 and 230 ng L-1, respectively). Two anti-
corrosive agents that are frequently used as additives in dishwasher tablets
were also detected (at a total concentration of 73 ng L-1) and were completely
dissolved in the aqueous phase of both influent and effluent water.
Figure 22. Effluent concentrations of selected tentatively identified sewage contaminants.
These findings of substances such as PPCPs and dishwasher tablet additives are
directly related to the intended uses of consumer products, and a direct
correlation can be seen between their use and STP effluent levels. Some
plasticizers and flame retardants, namely benzenesulfonamides (detected at 5.5
µg L-1) and the OPs (TBEP, 3.6 and TCEP, 0.36 µg L-1), respectively, were found
in similar concentrations to the PPCPs and other chemicals that are
intentionally used and thus released to the sewer system. These kinds of
compounds are probably slowly emitted from the stock of consumer articles
and building materials in society.
12000
5500
3600
2200930 460 360 230 110 73 23 2.8
0
2000
4000
6000
8000
10000
12000
14000
2,4
,7,9
-Tet
ram
eth
yl-
5-d
ecyn
-4
,7-d
iol
Be
nze
nes
ulf
on
amid
e
TB
EP
Be
nzo
thia
zole
Be
nzo
ph
en
on
e
Caf
fein
e
TC
EP
Oxy
ben
zon
e
DE
ET
An
ti-c
orr
osi
ve a
gen
ts
Car
ba
ma
zep
ine
1H
-In
do
le-3
-car
bo
xald
eh
yde
ng
L -1
7. NON-TARGETED SCREENING OF POORLY REMOVED CONTAMINANTS
71
Figure 23. Sources (origins) of the indicated percentages of the tentatively identified sewage contaminants.
Traditional approaches for assessing STP treatment efficiency
Analyses of STPs’ removal efficiencies usually focus on selected compounds or
groups of compounds. When target compounds are selected at early stages of a
study in such a manner, much of the subsequent experimental work and
analytical instrumentation that should be used is essentially predetermined. In
addition, method development may have been implemented, all of which limits
the scope for identifying both “new” potential compounds that are poorly
removed during sewage treatment and emerging pollutants. Benefits of such
approaches are that they can be optimized, thereby maximizing selectivity and
sensitivity. The drawbacks may be that these approaches discriminate against
many constituents of sewage, hence the results may give misleading overviews
of the overall environmental load derived from STPs and the ability to identify
poorly removed contaminants may be compromised. Thus, non-targeted
screening procedures, like the one developed in this study (Paper V), are
highly complementary to the traditional approaches.
To conclude, an environmetrics systematic approach was adopted and as
many as possible of the compounds that were poorly removed were tentatively
identified. This study demonstrates a new tool for identifying (GCxGC-
amenable) chemical substances that are not efficiently removed during current
sewage treatments. For non-polar and semi-polar compounds this
environmetrics approach seems to work satisfactorily. The results revealed
common structural features of the GCxGC amenable sewage contaminants for
22
16
1210
3
0
5
10
15
20
25
Tra
ffic
re
late
d
Fla
me
ret
ard
ants
and
pla
stic
izer
s
Foo
d a
dd
itiv
es
PP
CP
s
An
ti-c
orr
osi
veag
ents
%
7. NON-TARGETED SCREENING OF POORLY REMOVED CONTAMINANTS
72
which more effective treatment technologies need to be developed. In
comparison with traditional GC-MS methodologies this GCxGC approach
provides better chromatographic and mass spectrometric resolution. It also
provides comprehensive comparisons of influent and effluent concentrations,
and thus allows assessment of the STP removal efficiency of systematically
prioritized contaminants. Moreover, information on the tentatively identified
contaminants’ physicochemical properties, obtained from their 1D and 2D
retention times, can help assessments of their structures.
Although this study had limitations, notably the discrimination against polar
compounds (in extraction and instrumental analysis), it has provided new
knowledge that should facilitate the future development of STPs.
73
Conclusions
A number of conclusions have been drawn from the work underlying this
thesis. Firstly, the quality of the sewage sludge and the levels and distribution
patterns of the sludge contaminants, both within and between the STPs, seem
to remain quite constant over time. However, some minor variations were
observed using PCA (Paper III), notably high levels of PFCs appeared to be
related to textile industries and propiconazole to agricultural activities.
Nevertheless, the overall findings indicate that the levels of contaminants in
sewage sludge seem to be largely independent of the location, size and
treatment techniques applied at the STPs, and generally, of the types of human
activity connected to them. The total and relative concentrations of the sludge
contaminants were found to be fairly constant on a d.w. basis, with some
exceptions, indicating that the pollutants originate from broad usage and
diffuse dispersion rather than (industrial) point sources. Overall, of the
considered substances, metals and PCDD/Fs make the highest and lowest
contributions, respectively, to the environmental loads associated with sewage
sludge. The acquired data on levels, profiles and variations in sludge
contaminants (sludge quality), in studies III and IV (Papers III and IV) and
others extend both the available information and understanding of the degree
and nature of sludge contamination, which should help attempts to monitor
changes in its contaminants and revisions, if necessary, of limit values.
Secondly, significant time-trends in levels of a-third of the sludge contaminants
included in the national environmental monitoring program were detected
over a period of seven years (Paper IV). These contaminants include
representatives of almost all groups of investigated compounds. Thus, the
initial selection of compounds for inclusion in the sludge monitoring program
(focusing on chemicals that should have declined in environmental
compartments following restrictions on their use due to their adverse
8. CONCLUDING REMARKS AND FUTURE PERSPECTIVES
74
environmental effects) appears to have been successful. The levels of
compounds displaying significant time-trends generally decreased, due to
regulatory actions, following declines in the quantities used nationally.
However, a quarter of these compounds showed increasing trends (also in line
with use statistics).
It was also concluded, from results presented in Paper IV, that it will be
possible to tell if the substitution of brominated flame retardants, e.g. by
phosphorus-based flame retardants, is reflected in sewage sludge
concentrations in the future. Moreover, international and national
environmental legislation and regulations seem to be effective tools for
reducing releases of selected hazardous compounds into the environment, with
the possible exception of PBDE 209, which was regulated in the RoHS directive
in 2003 (EU, 2003), but its levels in sewage have not yet decreased. Increased
public awareness also seems to be important for environmental sustainability.
For example, levels of triclosan in both sludge and personal care products have
declined, although it is not regulated, probably because its toxicity to aquatic
organisms has been frequently highlighted in the media. Nevertheless, it is also
important to have powerful tools for assessing the effectiveness of measures
taken to reduce fluxes of chemicals from the technosphere to the environment.
Indications of the utility of retrospective temporal trend analyses of sludge
contaminant concentrations for this purpose were also obtained and presented
in Paper IV.
Thirdly, the STP removal efficiency of anthropogenic substances in Sweden is
generally good. However, results presented in Paper II indicate that STPs, at
least those in cold climates, do not efficiently remove certain polar
contaminants, and the temperature also seems to influence the distribution of
antibiotics between water and particulate matter (Paper I). Important tools for
predicting the behaviour and fate of anthropogenic substances after reaching
an STP are STP fate models, provided of course that their partitioning
coefficients and other parameters are sufficiently accurate. Therefore, the
validity of a fate model was assessed, and was found to provide poor
predictions of the proportions of polar compounds that partition to sewage
sludge (Paper II), hence fate models require improvement. In addition, despite
the relatively high removal efficiencies of the sludge contaminants observed in
study II, STPs remain potential sources of hazardous substances that may affect
organisms in aquatic and/or terrestrial environments. Thus, the treatment
process and plant design should be continuously refined to maximize the
8. CONCLUDING REMARKS AND FUTURE PERSPECTIVES
75
removal of undesirable substances from the sewage and thus minimize their
release into the environment.
In the last study (Paper V) a non-targeted screening (by use of environmetrics
and GCxGC-TOFMS) was performed and found to fulfil the objective to assess
the STP removal efficiency, with emphasis to systematically analyse which
compound classes that are not efficiently removed using the current STP
technology. Although the attempt was to perform a non-discriminating
screening, this environmetrics systematic approach has limitations in the
assessment of STP removal efficiency of polar compounds. The polar
compounds are discriminated in the extraction (by the use of dichloromethane
as extraction solvent) and in the instrumental analysis (by the use of GC).
Nevertheless, these results improve the knowledge base for the development of
future STP technologies.
Future aspects
The compounds considered in Paper IV are included in the on-going annual
Swedish environmental (sludge) monitoring program. Most of the compounds
monitored in sludge are now also being analysed in effluent water (since 2010).
At the same time, the following compounds were also included in the program:
alkylphenols, used in detergents; bisphenol A, used in food and drink
packaging; musk compounds, used in fragrances; and NSAIDs. In a few years
the data acquired in these annual measurements may be subjected to time-
trend analysis in the same manner as for the sludge (see Paper IV). However,
the long-term goal for this part of the program is to be able to detect changes in
total inputs of chemicals (via effluent and sewage sludge) from STPs into the
environment using estimates acquired from time-trend analysis of comparable
samples. This may improve knowledge of anthropogenic environmental
impacts via STPs, and understanding of the most effective actions for achieving
national environmental objectives and a greener world, today and in the future.
Revision of legislation and regulations, development of appropriate channels
for providing preventive information to the public, and use of government
grants to promote improvements in sewage treatment technologies may be
some measures that should be prioritized.
However, in order to increase sludge recycling and the public’s acceptance of
products grown on sludge-amended soil it is of utmost importance to identify
key sludge contaminants, assess their potential human and environmental
8. CONCLUDING REMARKS AND FUTURE PERSPECTIVES
76
risks, and take appropriate technical and/or regulatory actions to reduce the
emissions of pollutants that may pose a significant risk.
Since the untargeted assessment of STP removal efficiency focused on non- and
semi-polar compounds (Paper V), a complementary study focused on the polar
and non-biodegradable compounds should be performed using the same
approach. In such a study alternative extraction procedures (e.g. SPE
techniques capable of extracting highly polar compounds) and derivatisation
prior to GCxGC analysis or comprehensive LC should be applied. Finally, a fast,
high-resolution detection system would be required (e.g. high-resolution
TOFMS), providing accurate mass information to facilitate fast, accurate and
reliable identification of detected analytes.
Improvements of STPs
Both upstream measures and continuous refinements of treatment processes
are important to improve the sludge quality and reduce future environmental
impact on our lakes, rivers and coastal areas. In Sweden, since 2002 it has been
possible to certify the STPs (SWWA, 2008) in terms of their ability, for instance,
to meet national environmental goals for recycling phosphorus from sewage to
agricultural land (Swedish EPA, 2002). Currently 33 Swedish STPs are certified
(SP, 2011) and a further dozen have applied for certification. The aims of this
certification system are: to ensure that the nutrients from the sewage are
retained responsibly, and that all the health and safety requirements are met;
to make information about sludge production and its composition public; and
to provide a catalyst for further improvement of the raw sewage quality and
thus sludge quality.
Liming sludge has, for instance, prove to be an effective way to ensure that no
infections are spread, i.e. the liming kills germs. This treatment of sludge and
pasteurization are approved sanitation methods that allow the sludge to be
used as fertilizer in agriculture. Application of a thermophilic hydrolysis pre-
step to the anaerobic mesophilic digestion is currently under evaluation in
Sweden as a new sanitation approach (NSVA, 2011b) that may provide an
attractive alternative to pasteurization, with the possible potential to generate
more biogas.
8. CONCLUDING REMARKS AND FUTURE PERSPECTIVES
77
However, through the enormous flow of chemical substances that circulate in
the technosphere today, many undesirable (hazardous) compounds will reach
the sewer systems. Amounts of PPCPs, surfactants, industrial additives, EDCs
and numerous other compounds, e.g. alkylphenols, antibiotics, bisphenol A,
musk compounds, pesticides, phthalates, parabens (preservatives) and
steroidal estrogens used in modern society today are increasing. PPCPs and
EDCs are micro-contaminants (not currently regulated), which require
advanced STP technology for removal and thus elimination of the potential
threats they pose to aquatic organisms and human health. The current
technology of conventional STPs is not designed to remove emerging and new
contaminants. Their initial purpose was to remove nutrients and BOD and they
efficiently remove non-polar compounds, but not necessarily others. Therefore,
there is a need for alternative treatment steps in conventional STPs that are
capable of removing water soluble contaminants, but this is challenging due to
the wide range of physicochemical properties of these emerging and new
compounds.
Alternative treatment steps
Advanced techniques, such as activated carbon or membrane-filtration based
separation, oxidation (by ozonation, O3, chlorination, or ultraviolet light in
combination with hydrogen peroxide, UV/H2O2) have been discussed as
additional treatment steps globally. The separation techniques are not
destructive methods and the compounds are either separated by adsorption or
semi-permeable membranes and high differential pressures, while the
oxidative methods totally (or partly) break down or convert the compounds.
Such treatment processes have not yet been implemented in most conventional
STPs, but they all have specific benefits and limitations for removing trace
contaminants.
Powder activated carbon (PAC), treatments show promising potential for
dealing with many EDCs (Westerhoff et al., 2005), providing >90% removal
efficiencies with a 5 mg L-1 dose of PAC and 4 hour contact time. PAC also seems
to work better for hydrophobic compounds (log Kow > 5) than for polar
compounds. Granular activated carbon (GAC) has similar efficacy (Kim et al.,
2007) but is preferable (although its lower surface-area-to-volume ratio than
PAC) because it facilitates subsequent work as it can be destroyed (combusted
with energy recovery) or regenerated and will not end up in the sludge, unlike
the powdered form. Other promising techniques are membrane filtration
8. CONCLUDING REMARKS AND FUTURE PERSPECTIVES
78
methods, such as nanofiltration (NF; pore size, ~1 nm) and reverse osmosis
(RO; pore size, ~0.1 nm), although concentrates generated by these filtration
methods must be further processed, e.g. by ozonation. Kim et al. (2007) found
that NF and RO provided excellent removal of several PPCPs and TCEP (> 95%
for all those tested). They also suggested using GAC and membrane filtration
(NF or RO) for efficient removal of micro-contaminants. In practice, NF may be
preferable due to the higher pressure (higher energy) required for RO and the
higher amounts of salts that are separated, but both GAC separation and NF
seem to be interesting processes that are capable of removing micro-
contaminants such as PPCPs and EDCs.
Oxidation processes, such as ozonation and chlorination, remove reactive
compounds containing aromatic structures with hydroxide functional groups
(removal efficiencies > 90%, slightly higher for ozonation; Westerhoff et al.,
2005). Huber et al. (2005) concluded that an O3 dosage of 5 mg L-1 is sufficient,
but higher dosage may be needed when suspended solid concentrations are
high, with consequent increases in energy consumption. One benefit of
ozonation, besides removal of contaminants, is that the effluent water will be
disinfected. Removal can also be enhanced slightly by adding hydrogen
peroxide during ozonation (O3/H2O2).
To be able to oxidize (remove) as many contaminants as possible, to CO2 and
H2O, the amount of O3, the water temperature and the pH must all be optimized.
Unfortunately, high amounts of O3 would be required at the typical
temperatures (10-20 °C) and pH (ca. 7) of sewage in Swedish STPs. However,
chlorination processes should be avoided due to their production of chlorine
by-product (Buth et al., 2011), which reacts with EDCs, and although UV
processes provide high removal of PPCPs and EDCs, very high (and costly) UV
levels are needed (Adams et al., 2002). Using UV/H2O2 generates hydroxyl
radicals that are more effective oxidation agents (and more complex) than O3.
However, a critical factor with all these reactive techniques is the potential
production of toxic transformation products from sewage contaminants.
8. CONCLUDING REMARKS AND FUTURE PERSPECTIVES
79
To summarize, there are currently several alternative treatment steps that
could complement conventional STP processes to reduce levels of poorly
removed contaminants. It should be noted that in addition to improving
removal efficiencies of undesirable compounds in sewage, new techniques
should consume as little energy as possible, for direct financial and indirect
environmental reasons. If no formation of harmful by-products can be shown to
occur during ozonation this technique seems to be the most promising main
alternative, as it is also the most cost effective option.
A research project has been initiated recently in Sweden to evaluate various
technologies to reduce contaminants and pharmaceutical residues from
sewage, focusing largely ozonation and disc filtration (NSVA, 2011a). This study
is being carried out using a pilot-scale treatment plant, and since the target
compounds are not normally removed during conventional treatments the
additional treatment steps are applied at the end of the process.
It should though be interesting to evaluate if such a treatment step as ozonation
could be applied during the aeration before the biological process, in STPs that
have this process before the effluent exit. In such an implementation the
potential breakdown products by O3 may then be removed during the
biological treatment hence minimizing the release of undesirable (toxic)
compounds via the STP effluent into the environment. However, one drawback
may be the higher amount of O3 that may be required due to the higher content
of suspended materials (solids) during aeration than at the end of the process.
80
81
TACK till alla som på ett eller annat sätt har gjort denna resa möjlig. Speciellt
stort tack går till mina kära barn, ni är bara bäst och ni förgyller mitt liv i stort
som smått. Vad vore livet utan er kärlek? Jag älskar er och ni har alla en given
plats i mitt hjärta. Min hjärtevän, du har också en given plats i mitt hjärta och
med följande tre ord sammanfattar jag vad du betyder för mig – jag älskar dig!
Vilken tur att man har ett stort hjärta som gör att kärleken räcker till er alla.
TACK till mina handledare, ni har självklart varit värdefulla bollplank och ni
har på ett eller annat sätt bidragit till att denna bok nu äntligen är klar. Peter
Haglund, tack för att du trodde på mig! Du besitter en sådan enorm kunskap
inom en mängd områden (även utanför din expertis) som du har delat med dig
av under resans gång och som har givit mig ovärderlig kompetens inom
miljökemins underbara värld. Staffan Lundstedt, du tar dig verkligen tid att
besvara alla möjliga frågor och jag har aldrig tvekat att rådfråga dig när det har
uppstått funderingar. Jag lever efter devisen, ”det är bättre att ställa dumma
frågor än att göra dumma misstag”, vilket jag tror att ni vid det här laget känner
till.
TACK alla ni andra på ”miljökemi” (nya som gamla miljökemister) som jag har
haft nöjet att lära känna och arbeta med under alla dessa år. Ni har också på ert
alldeles speciella sätt mer eller mindre bidragit till att målet nu är nått. Ingen
nämnd och ingen glömd.
TACK till mina medförfattare, för intressanta diskussioner och ett gott
samarbete. Ni är alla guld värda.
TACK till all personal vid reningsverken, för er hjälpsamhet med provtagning
och delgivande av signifikant processinformation.
TACK till Naturvårdsverket, för finansiering och till Knut och Alice Wallenbergs
Stiftelse och COST Action 636, för ekonomiska bidrag till konferensresor.
TACK mor och far för att ni finns, och kom ihåg - kärleken övervinner allt.
TACK käre bror, för den tid vi fick tillsammans.
Ulrika Olofsson
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A1
Molecular structures of the compounds included in this thesis.
Adipates
Diethyl adipate (DEAP)
Dibutyl adipate (DBA)
Di-iso-butyl adipate (DIBA)
Di(2-ethylhexyl) adipate (DEHA)
Dioctyl adipate (DOA)
Di-iso-octyl adipate (DIOA)
Didecyl adipate (DDA)
Di-iso-decyl adipate (DIDA)
Biocides
Benzylparabene
Butylparabene
Ethylparabene
Methylparabene
Propylparabene
4-Chloro-3-cresol
O
OCH3
O
O CH3
O
OCH3
O
O CH3
O
O
CH3
CH3
O
O
CH3
CH3
O
O CH3
CH3O
OCH3
CH3
O
OCH3
O
O CH3
O
O
CH3
CH3
O
O
CH3
CH3
O
O CH3
O
OCH3
O
O
CH3
CH3
O
O
CH3
CH3
O
O
OH
O
O
CH3
OH
O
O
CH3OH
O
O CH3
OH
O
O
CH3
OH
OH
CH3
Cl
A2
2-Mercaptobenzothiazole
2-(Tiocyanomethylthio)benzothiazole
N-didecyldimethylammonium chloride (DDMAC)
Propiconazole
Resorcinol
Triclosan (TCS)
Chlorophenols (CPs)
2-monochlorophenol (2-CP)
3-monochlorophenol (3-CP)
4-monochlorophenol (4-CP)
2,3-dichlorophenol (23-CP)
2,4-dichlorophenol (24-CP)
2,5-dichlorophenol (25-CP)
2,6-dichlorophenol (26-CP)
3,4-dichlorophenol (34-CP)
3,5-dichlorophenol (35-CP)
2,3,4-trichlorophenol (234-CP)
N
S
SH
N
S
S
N S
NCl
CH3CH3
CH3CH3
ClCl
N
N
N
O CH3
O
OH
OH
O
OH
Cl ClCl
OH
Cl
OH
Cl
OHCl
OH
Cl Cl
OHCl
Cl
OH
Cl
Cl
OH
Cl
Cl
OHCl
Cl
OH
Cl
Cl
OHCl
Cl Cl
A3
2,3,5-trichlorophenol (235-CP)
2,3,6-trichlorophenol (236-CP)
2,4,5-trichlorophenol (245-CP)
2,4,6-trichlorophenol (246-CP)
3,4,5-trichlorophenol (345-CP)
2,3,4,5-tetrachlorophenol (2345-CP)
2,3,4,6-tetrachlorophenol (2346-CP)
2,3,5,6-tetrachlorophenol (2356-CP)
Pentachlorophenol (PCP)
Butylhydroxytoluene (BHT)
4-Nonylphenol (4NP)
OH
Cl
Cl Cl
OH
Cl
Cl
Cl
OH
Cl
Cl
Cl
OHCl
Cl
Cl
OH
Cl
Cl
Cl
OH
Cl
Cl
Cl Cl
OH
Cl
Cl
Cl
Cl
OH
ClCl
Cl Cl
OH
Cl
Cl
Cl Cl
Cl
OHCH3
CH3
CH3CH3
CH3 CH3
CH3
OH
CH3
CH3
CH3
CH3
A4
Organophosphorus compounds (OPs)
Tributyl phosphate (TBP)
Tris(2-butoxyethyl) phosphate (TBEP)
Triphenyl phosphate (TPP)
2-Ethylhexyl phosphate (EHDPP)
Tricresyl phosphate (TCP)
Tris(2-chloroethyl) phosphate (TCEP)
Tris(2-chloroisopropyl) phosphate (TCPP)
Tris(1,3-dichloro-2-propyl) phosphate (TDCPP)
O
P O
CH3
O
CH3
O
CH3
OPO
O
CH3
O
O
CH3
O
OCH3
O
P
O
O
O
OP
O
O
O
CH3
CH3
O
P
O
CH3O
CH3
O
CH3
OPO
Cl
O Cl
O
Cl
OPO
Cl
CH3O Cl
CH3
O
Cl
CH3
OPO
Cl
Cl
O Cl
Cl
O
Cl
Cl
A5
Organotin compounds (OTCs)
Monobutyltin (MBT)
Dibutyltin (DBT)
Tributyltin (TBT)
Monophenyltin (MPhT)
Diphenyltin (DPhT)
Triphenyltin (TPHT)
Perfluorochemicals
(PFCs)
Perfluorohexane acid (PFHxA)
Perfluoroheptane acid (PFHpA)
Perfluorooctane acid (PFOA)
Perfluorononane acid (PFNA)
Perfluorodecane acid (PFDA)
Perfluoroundecane acid (PFUnA)
Perfluorododecane acid (PFDoDA)
Perfluorotridecane acid (PFTrDA)
Perfluorotetradecane acid (PFTeDA)
CH3
SnH(II)
CH3
Sn(II)
CH3
SnH
CH3
CH3CH3
SnH(II)
Sn(II)
SnH
O
OH
F
F
F
F
F
F
F
F
F
F
F
O
OH
F
F
F
F
F
F
F
F
F
F
F
F
F
O
OH
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
O
OH
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
O
OH
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
OH
O F
F
F
F
F
F
F
F
F
F F
F F
F F
F F
F
F
F
F
O
OH
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
O
OH
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
O
OH
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
A6
Perfluorohexane sulfonate (PFHxS)
Perfluorooctane sulfonate (PFOS)
Perfluorodecane sulfonate (PFDS)
Perfluorooctane sulfonamide (PFOSA)
Pesticides
Herbicides
Aclonifen
Alachlor
Aminomethylphosphonic acid (AMPA)
Atrazine
Carfentrazone ethyl
Chloridazon
Chlorpropham
Cinidon ethyl
Cyanazine
S
O
O
O
K
F
F
F
F
F
F
F
F
F
F
F
F
F
S
O
O
O
K
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
O S
O
OH
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
O
S
O
NH
CH3
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
O
Cl
NH2N+
O-
O
CH3
CH3 N
O CH3
O
Cl
OP
NH2
OH
OH
N
N
N
NH
CH3
CH3
NH
CH3
Cl
F
ClClO
O
CH3
N
ON
F F
CH3
N
N
OCl
NH2
N
CH3
CH3
O
O
NH
Cl
O
O
N
O
O
Cl
Cl
CH3
CH3
NH
N
Cl
N
NH
CH3
CH3
N
N
A7
Desethylatrazine (DEA)
Desisopropylatrazine (DIPA)
Dichlorobenil
Diflufenican
Ethofumesate
Flurtamone
Glyphosate
Hexazinone
Metabenzthiazuron
Metamitron
Methazachlor
Metribuzin
Pendimethaline
Cl
N
NH
CH3
CH3
N
NH2
N
Cl
N
NH2
N
NH
CH3 N
Cl
Cl
N
N
O
F
F
F
O
NH
F
F
CH3
O
O
OS
CH3
O
OCH3
CH3
O
F
F
F
NHCH3 O
OH
O
NH
P OHOH
OO
N
N
OCH3
N
CH3
CH3
N
CH3 NH
O
N
CH3N
S
NN
CH3
N
NH2 O
CH3
CH3 N
O
Cl
N N
O
N
NH2S
CH3
N
N
CH3 CH3
CH3
CH3
CH3NHCH3
CH3 N+
O-
O
N+O-
O
A8
Phenmedipham
Propyzamide
Prosulfocarb
Simazine
Terbuthylazine
Terbuthylazine desethyl
(DETA)
Terbutryn
Trifluralin
Fungicides
Azoxystrobine
BAM (2,6-dichlorobenzamide)
Bitertanol
Captan
CH3
NH
O
O
NH
O
OCH3
CH3
CH3
NH
O
Cl
Cl
CH
S
O
N CH3
CH3
N
N
N
NH
CH3
NH
CH3
Cl
N
N
N
NH
CH3
CH3
CH3
NH
CH3
Cl
O
N
CH3
CH3
CH3
CH3
NH
N
NHCH3
CH3CH3
N
SCH3
N
CH3
N CH3
N+
O-
O
F
F
F
N+O-
O
N
O
N N
O
O
OCH3
OCH3
NH2
O
Cl
Cl
O
OH
CH3
CH3CH3
N N
N
O
N
SCl
ClCl
O
A9
Chlorothalonil
Cyprodinil
Diphenylamine
Diuron
Fenpropimorph
Imazalil
Iprodione
Isoproturon
Metalaxyl
Pentachloroaniline
Prochloraz
Propiconazole
Pyraclostrobin
N
N
Cl
Cl Cl
Cl
NH
NCH3
N
NH
O
N
CH3
CH3NH
Cl
Cl
CH3
CH3
CH3
CH3N
CH3
O
CH3
Cl
Cl
O
CH2
N
N
Cl
Cl
N
O
NO
NHCH3
CH3
O
CH3
CH3
NH
O
N
CH3
CH3
CH3OO
N
CH3
O
O
CH3
CH3
CH3
NH2
ClCl
Cl
Cl Cl
Cl
Cl
Cl O
N CH3
O
N
N
Cl
Cl
N
N
N
O
CH3
O
O
O
CH3
N
O CH3
O
NN
Cl
A10
Pyrimethanil
Quintozene
Spiroxamine
Thiabendazole
Tolchlofosmethyl
Tolylfluanid
Vinclozolin
Insecticides
Acephate
Aldrin
Azinophosmethyl
Bromopropylate
Carbaryl
Carbofuran
Carbophenothion
NH
N
CH3
CH3
N
O-
N+
O
Cl
Cl
Cl Cl
Cl
CH3
CH3
CH3O
N
CH3
CH3
O
N
N
H
S
N
SP
O
CH3
O CH3
O
Cl
CH3
Cl
CH3
N
CH3
S
O
O
N
S
F
Cl
Cl
CH3
Cl
Cl
N
OCH3CH2
O
O
CH3 O
P
O
NH
CH3
O
SCH3
Cl
ClCl
Cl
Cl
Cl
S
PO
CH3
O
CH3
S
N
NN
O
OHBr
Br
O
O
CH3
CH3
O
O
NH
CH3
O
O
O
CH3CH3
NH
CH3
CH3
OP
S
O
CH3
S
SCl
A11
Carbosulfan
α-chlordane
γ-chlordane
Chlorfenvinphos
Chlorobenzilate
Chlorpyrifos
λ-cyhalotrin
Cyflutrine
β-cyflutrine
α-cypermethrine
Cypermethrine
O
CH3
CH3
O
O
N
CH3
SN
CH3
CH3
Cl
ClCl
Cl
Cl
Cl
Cl
Cl
Cl
ClCl
Cl Cl
Cl
Cl Cl
CH3
O
PO
OCH3
O
Cl
Cl
Cl
O
O
CH3
OHCl
Cl
CH3
O
P
S
O
CH3
O
N
Cl
Cl
Cl
F
F
F Cl
CH3
CH3
O
O
N
O
CH3
CH3 Cl
Cl
O
O
N
F
O
CH3
CH3 Cl
Cl
O
O
N
F
O
Cl
Cl
CH3
CH3
O
O
N
O
Cl
Cl
CH3
CH3
O
O
N
O
A12
DDD-p,p
DDE-p,p
DDT-o,p
DDT-p,p
Deltamethrine
Diazinon
Dichlorvos
Dieldrin
Dimethoate
α-endosulfan
β-endosulfan
Endosulfan sulfate
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl Cl
Cl
CH3
CH3 Br
Br
O
O
N
O
OP
OCH3
O
N
N
CH3
CH3
CH3
S
CH3
O P
OCH3
O
CH3
O
Cl
Cl
Cl
ClCl
O
Cl
Cl
Cl
O
NH CH3
S
P O
CH3
O
CH3
S
Cl
ClCl Cl
Cl
Cl
O
S
O O
O S
O
O
Cl
Cl
Cl
Cl
Cl
Cl
ClCl
Cl
O
SO
OO
Cl
Cl
Cl
A13
Endrin
Esfenvalerate
Fensulfothion
Fenvalerate
Flucythrinate
α-, β-, δ-, γ-HCH (γ-HCH: Lindane)
Heptachlor
Heptachlorepoxide
Keto-endrin
Methidathion
Methoxychlor
Parathion ethyl
Parathion methyl
Cl
ClCl
O
Cl
Cl
Cl
Cl
CH3
CH3 O
O
N
O
CH3
OP
S
O
CH3
OS
CH3
O
CH3
CH3
O
O
N
O
Cl
CH3
CH3
O
O
N
O
O
F
F
Cl Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
ClCl
Cl
Cl
O
Cl
Cl
Cl
ClCl
Cl
Cl
O
Cl
Cl
Cl
Cl
Cl
S P
OCH3
O
CH3
S
N
O
S
OCH3 N
CH3
O
O
CH3
Cl
Cl
Cl
CH3
OP
S
O
CH3
ON+
O-
O
CH3 O
P
S
OCH3
ON+
O-
O
A14
Permethrine
Pirimicarb
Pirimiphos methyl
Propargite
Propoxur
Pyridaben
Quinalphos
Tetradiphone
Pharmaceuticals
Antibiotics
Ciprofloxacin
Norfloxacin
Ofloxacin
Trimethoprim
CH3
CH3Cl
Cl
O
O
O
CH3
N
CH3O
O
N
N
CH3 CH3
N
CH3
CH3
CH3
N
CH3N
CH3
OP
S
O
CH3
O
CH3
N
CH3
CH3
CH3
OOS
O
O
CH
CH3
NH
O
O
O
CH3
CH3
CH3
CH3
CH3S
ClO
N
CH3
CH3
CH3 N
CH3
OP
S
O
CH3
O
N
N
ClS
O
O
Cl
Cl
Cl
NHN
NO
OH
O
F
NHN
N
CH3
O
OH
O
F
N CH3N
F
O
O
OH
N O
CH3
OCH3
O
CH3OCH3
NH2
N
NH2 N
A15
Hormones
Estriol
Estradiol
Ethinylestradiol
Norethindrone
NSAIDs
Ibuprofen
Naproxen
Ketoprofen
Diclofenac
Tetracyclines (TCs)
Oxytetracycline
Tetracycline
Demeclocycline
Chlorotetracycline
Doxycycline
CH3
OH
OH
OH
CH3
OH
OH
OH
CHOH
CH3
CH3
O
OH
CH
O
OH
CH3
CH3 CH3
CH3
O
CH3
OH
O
O
O
OH
CH3
OH
O
NH
Cl
Cl
H
HOH
H
OOH
CH3 OH
OHOH
O
NH2
O
OH
H N
CH3
CH3
HH
OOH
CH3OH
OHOH
O NH2
O
OH
HN
CH3
CH3
OH O OHOH
O
O
NH2
OH
NCH3 CH3
OHCl
O
NH2
OH
NCH3 CH3
OHOH
OH
OH
Cl CH3
O O
CH3 OH NCH3 CH3
NH2
O
OOH
OOH OH
OH
A16
Phthalates
Dimethyl phthalate (DMP)
Diethyl phthalate (DEP)
Di-n-butyl phthalate (DBP)
Butylbenzyl phthalate (BBP)
Di-(2-ethylhexyl) phthalate (DEHP)
Di-n-octyl phthalate (DNOP)
Di-iso-decyl phthalate (DIDP)
Di-iso-nonyl phthalate (DINP)
O
OCH3
O
OCH3
O
O CH3
O
O CH3
O
O CH3
O
O CH3
O
O
O
O CH3
O
OCH3
CH3
O
O CH3
CH3O
O CH3
O
O CH3
CH3
CH3
O
O
O
O
CH3CH3
O
O
O
CH3
CH3
O
CH3
CH3
A17
Polybrominated diphenyl ethers (PBDEs)
PBDE 28
PBDE 47
PBDE 99
PBDE 100
PBDE 153
PBDE 154
PBDE 183
PBDE 209
Polychlorinated alkanes (PCAs)
Short chain chlorinated paraffins (SCCP)
Medium chain chlorinated paraffins (MCCP)
Long chain chlorinated paraffins (LCCP)
Br
Br
O
Br
Br
Br
O
Br
Br
Br
Br
O
Br
Br
Br
Br
O
BrBr
Br Br
Br
Br
OBr
Br Br
Br
Br
Br
O
Br
Br
Br
Br
Br
Br
O
Br
Br
Br
Br
Br
OBr
Br
Br
Br
Br
Br
Br
Br
Br
Br
CH3
Cl
CH3
CH3
Cl
CH3
CH3
Cl
CH3
A18
Polychlorinated biphenyls (PCBs)
PCB 28
PCB 52
PCB 101
PCB 105
PCB 114
PCB 118
PCB 123
PCB 138
PCB 153
PCB 156
PCB 157
PCB 167
PCB 180
PCB 189
Cl
Cl Cl
Cl
ClCl
Cl Cl
ClCl
Cl
Cl
Cl Cl Cl
ClCl
Cl Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl Cl
Cl
ClCl
Cl
Cl Cl Cl
Cl
Cl
Cl
Cl
ClCl
Cl
Cl Cl
Cl Cl Cl
Cl
ClCl
Cl
Cl Cl Cl
Cl
ClCl
Cl
A19
Planar PCBs
PCB 77
PCB 81
PCB 126
PCB 169
Polychlorinated dioxins/furans (PCDD/Fs)
Polychlorinated dibenzo-p-dioxins (PCDDs)
2,3,7,8-TCDD
1,2,3,7,8-PeCDD
1,2,3,4,7,8-HxCDD
1,2,3,6,7,8-HxCDD
1,2,3,7,8,9-HxCDD
1,2,3,4,6,7,8-HpCDD
OCDD
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
ClCl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
ClOCl
Cl O Cl
Cl
O Cl
ClO
Cl
Cl
Cl
Cl
Cl
Cl
O
ClO
Cl
ClO
O
Cl
ClCl
Cl
Cl
Cl
O
Cl
Cl
ClO
Cl
Cl
Cl
Cl
Cl
O Cl
Cl
Cl
O
Cl
Cl
Cl
Cl
O
Cl
Cl
Cl
Cl
O
Cl
A20
Polychlorinated dibenzofurans (PCDFs)
2,3,7,8-TCDF
1,2,3,7,8-PeCDF
2,3,4,7,8-PeCDF
1,2,3,4,7,8-HxCDF
1,2,3,6,7,8-HxCDF
2,3,4,6,7,8-HxCDF
1,2,3,7,8,9-HxCDF
1,2,3,4,6,7,8-HpCDF
1,2,3,4,7,8,9-HpCDF
OCDF
Cl
O
Cl
Cl Cl
ClCl
Cl
Cl
O
Cl
ClCl
Cl
OCl
Cl
ClCl
Cl
Cl
OCl
Cl
ClCl
Cl
Cl
ClO
Cl
ClCl
Cl
ClO
Cl
Cl
Cl
O
ClCl
Cl Cl
Cl
ClCl
Cl
Cl
ClO
Cl
Cl
Cl
O
ClCl
Cl
Cl
Cl
Cl
Cl
ClCl
OCl
Cl
ClCl
Cl
A21
Polychlorobenzenes (PCBz)
1,2-dichlorobenzene (12CBz)
1,3-dichlorobenzene (13CBz)
1,4-dichlorobenzene (14CBz)
1,2,3-trichlorobenzene (123CBz)
1,2,4-trichlorobenzene (124CBz)
1,3,5-trichlorobenzene (135CBz)
1,2,3,4-tetrachlorobenzene (1234CBz)
1,2,3,5-tetrachlorobenzene (1235CBz)
1,2,4,5-tetrachlorobenzene (1245CBz)
Pentachlorobenzene (PCBz)
Hexachlorobenzene (HCBz)
Polycyclic aromatic hydrocarbons (PAHs)
Fluoranthene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Benzo(a)pyrene
ClCl
Cl
Cl
Cl
Cl
Cl
ClCl
Cl Cl
Cl
Cl
Cl
Cl
Cl
Cl
ClCl
Cl Cl
Cl
Cl
Cl Cl
ClCl
Cl Cl
Cl
ClCl
Cl Cl
Cl
Cl
Cl
Cl
A22
Benzo(g,h,i)perylene
Benzo(g,h,i)perylene
Siloxanes
Octamethylcyclotetrasiloxane (D4)
Decamethylcyclopentasiloxane (D5)
Dodecamethylcyclohexasiloxane (D6)
Hexamethyldisiloxane (MM)
Octamethyltrisiloxane (MDM)
Decamethyltetrasiloxane (MD2M)
Dodecamethyltetrasiloxane (MD3M)
Terpenes
d-, l-limonene
CH3Si
CH3O
Si
CH3
CH3
O
SiCH3
CH3
OSi
CH3
CH3
O
CH3Si
CH3OSi
CH3CH3
O
Si
CH3
CH3 O
Si
CH3 CH3
O
Si
CH3
CH3
O
CH3Si
OSiO
Si
O
Si
O Si
CH3CH3
O
Si
O
CH3
CH3CH3
CH3
CH3
CH3
CH3CH3CH3
CH3Si
CH3
CH3
OSi
CH3
CH3
CH3
CH3
Si
CH3
CH3OSi
CH3
CH3
O
Si
CH3
CH3
CH3
CH3
SiCH3
CH3
O
Si
CH3
CH3
OSi
CH3
CH3
O
Si
CH3
CH3
CH3
CH3
Si CH3
CH3O
SiCH3
CH3
O
Si
CH3CH3
OSi
CH3
CH3
OSi
CH3
CH3 CH3
CH2
CH3
CH3