report on environmentally relevant heavy metals in p-fertilizer … · 2017-07-04 · report on...

BONUS PROMISE DELIVERABLE 2.3

Report on environmentally relevant heavy metals

in P-fertilizer materials

Minna Sarvi, Kari Ylivainio, Eila Turtola

DEL 2.3 BONUS PROMISE

2

Phosphorus Recycling of Mixed Substances (BONUS PROMISE)

DELIVERABLE 2.3

Report on environmentally relevant heavy metals

in P-fertilizer materials

AUTHORS: Minna Sarvi, Kari Ylivainio, Eila Turtola

DATE: March, 2017

BONUS PROMISE project has received funding from BONUS

(Art 185), funded jointly by the EU and Ministry of Agriculture

and Forestry, PTJ and VINNOVA


3

Contents

1. Summary ......................................................................................................................................... 4

2. Introduction .................................................................................................................................... 4

3. Material and methods .................................................................................................................... 6

3.1 Sampling .................................................................................................................................. 6

3.2 Determination of heavy metals .............................................................................................. 7

4. Results ............................................................................................................................................. 7

4.1 Heavy metal concentrations in P sources ..................................................................................... 7

4.2 ASH DEC-process ......................................................................................................................... 12

5. Conclusions ................................................................................................................................... 14

6. References .................................................................................................................................... 15

Appendix I

Appendix II


4

1. Summary Food production in EU is largely dependent on imported non-renewable primary phosphorus (P)

minerals. However, P reserves are depleting and their quality is declining in the future highlighting

the importance of more effective recycling of organic materials containing P. Like inorganic P

fertilizer, also the organic P sources contain heavy metals. In manures heavy metals originate mainly

from feed and pharmaceuticals and concentrations vary both between and within the animal types.

For municipal sewage sludges, industrial flows often increase their heavy metal contents. In this

study we examined heavy metal concentrations in different P sources. We also studied the

effectiveness of ASH DEC –process to reduce heavy metal contents in sewage sludge ash. Among the

studied P sources zinc (Zn, 27 g kg-1 P), copper (Cu, 7 g kg-1 P), chromium (Cr, 0.8 g kg-1 P) and nickel

(Ni, 0.4 g kg-1 P) were the most abundant heavy metals, whereas mercury (Hg, 5 mg kg-1 P) and

cadmium (Cd, 17 mg kg-1 P) had the lowest concentrations. In manures, Zn and Cu concentrations

were highest and their concentrations decreased in the order pig > poultry > cattle manure. In

manures, heavy metal concentrations were generally higher than in superphosphate (where the

apatite originates from Siilinjärvi mine), but lower than in solid sewage sludges. In solid sewage

sludges the most abundant heavy metals were Zn, Cu, Cr, Ni, uranium (U) and lead (Pb) and

concentrations were higher than in superphosphate. Sewage sludges sampled from Finland and

Sweden had higher U concentrations (Sweden: 1072 mg kg-1 P, n=3; Finland: 593 mg kg-1 P, n=6) than

those sampled in Germany (52 mg kg-1 P, n=1) probably due to the geology of these areas. Struvite,

liquid fraction of sewage sludge and superphosphate had most often the lowest heavy metal

concentrations. ASH DEC –process reduced Cd by 59% and Hg concentrations from 0.3 to <0.02 mg

kg-1 DM compared to the sewage sludge used as feeding material, whereas Cr and Ni contents

increased due to the corrosion of unprotected steel reactor walls of test equipment in contrast to

refractory lined industrial equipment.

2. Introduction Phosphorus (P) is an essential major plant nutrient that cannot be substituted by any other element

and thus it is crucial for the food production. At present agriculture mainly uses P obtained from

phosphate rock and is therefore dependent on non-renewable resources (Cordell et al. 2009, van

Dijk et al. 2016). According to Cordell et al. (2009) easily exploitable rock phosphate reserves will be

depleted in 50-100 years. Furthermore, the quality of the remaining rock phosphate reserves will

decline in terms of heavy metals. The reserves are controlled by few countries, making P supply

vulnerable to geopolitical issues. Cooper et al. (2011) highlighted that 77% of known P rock reserves

are located in Morocco and its share is estimated to increase in the future. At present EU’s food

production is already dependent on imported primary P (van Dijk et al. 2016). Both the declining

quality and imbalanced regional distribution of P rocks will affect the accessibility and price of P

fertilizers in the near future. Therefore more efficient utilization of the inorganic P as well as

recycling of organic materials containing P has drawn more attention.

Despite of the growing awareness, P recycling rate and efficiency are relatively low at the EU level

(van Dijk et al. 2016). While manures are almost fully recycled at the EU level (van Dijk et al. 2016),

their use may be very inefficient. Manures are often spread near the production houses due to the

high transportation costs because of low nutrient and high water content. This will result in high soil

phosphorus level with increased P leaching risk near the animal production units (e.g. Ylivainio et al.


5

2014). Sewage sludges are regionally even more concentrated. Because both manures and sewage

sludges may contain inorganic (heavy metals) and organic contaminants (e.g. pharmaceuticals),

there is a risk for their accumulation in soils as well and bioaccumulation in the food chain. For

example, Sheppard and Sanipelli (2012) noticed Zn accumulation in soils with long-term manure

application.

In manures, heavy metals largely originate from feed since e.g. Cu, Zn and cobolt (Co) are used as

feed additives to avoid deficiencies and promote animal health and growth (e.g. Poulsen 1998, Bolan

et al. 2004, Sheppard and Sanipelli 2012). In general, heavy metal concentrations in manures reflect

their concentrations in feedstuffs (Nicholson et al. 1999, Sheppard and Sanipelli 2012). Once

ingested, heavy metals mainly pass through the animal and end up to manure (Sheppard et al. 2010,

Sheppard and Sanipelli 2012). Other sources of heavy metals in livestock production are

pharmaceuticals (e.g. Bolan et al. 2004, Sheppard and Sanipelli 2012). Heavy metal concentrations in

manures vary between different animals and among the animal type. For example, Sheppard and

Sanipelli (2012) noticed that layer manure had the highest heavy metal concentrations (except Cu)

among poultry manure and among swine manures Cu and Zn concentrations were significantly

higher in nursery barns than in other swine barns. In contrast the concentrations were much less

variable in dairy manures. Nicholson et al. (1999) noticed that Zn and Cu were the most important

heavy metals in manures and their concentrations decreased in the following order: pig manures >

poultry manures > cattle manures.

In sewage sludges Cd, Cr, Cu, Hg, Ni, Pb, Zn and arsenic (As) are generally considered to be the most

relevant heavy metals. They originate from discharge of households, run-off and industrial waste

water (Sörme and Lagerkvist 2002). In addition U, known to be chemotoxic, radiotoxic and

carsinogenic element, can occur in sewage sludges (Bastian et al. 2005, Kratz et al. 2008, Jiménes et

al. 2011). Naturally the heavy metal concentrations in sewage sludges vary depending on the

activities in the catchment area and sources of the waste water entering the treatment plant.

Industrial processes often elevate the heavy metal contents of sludges (Herzel et al. 2016). In a case

study in Stockholm, Sörme and Lagerkvist (2002) calculated that households were the main source

for Cu, Zn and Hg. The main source of Cu was from pipes and taps and roofs, Zn from food, pipes and

taps but also from galvanized goods and car washes. Car washes dominated Cd, Pb and Cr emissions.

The heavy metal concentrations in sewage sludges have decreased over the decades, however (e.g.

Sörme and Lagerkvist 2002, European Commission 2010).

There are great variation in sewage sludge treatment methods and disposal practices between EU

member states (Kelessidis and Stasinakis 2012, Hukari et al. 2016). Commonly used treatment

methods in the EU are aerobic and anaerobic digestion, lime stabilization, composting, thermal

drying and long-term storage (Kelessidis and Stasinakis 2012). According to Kelessidis and Stasinakis

(2012) most of the sludge produced in the EU is used in agriculture (41%) followed by smaller shares

of incinerating (19%), landfilling (17%) and composting (12%). Incineration is most common in the

Netherlands (68%), Belgium (53%) and Germany (51%). In case of sewage sludge ashes (SSAs) their

low P availability together with elevated heavy metal contents often restricts their use as fertilizers

unless further treated (Krüger and Adam 2015). By far many different technologies at various phase

of development have been investigated to reduce heavy metal content in the end-product when

recovering P from SSAs (Egle et al. 2015). One of these technologies is Outotec’s thermochemical

ASH DEC –treatment, where sodium sulfate (Na2SO4) is mixed with SSA after which the mixture is


6

treated in a rotary kiln at high temperatures to produce more bioavailable P compounds with

reduced heavy metal contents (Egle et al. 2015, Havukainen et al. 2016).

The aim of this study was to examine the heavy metal contents in different kinds of organic P

sources, derived from manures and sewage sludges as well as in struvite and ASH DEC –material

(sewage sludge as a starting material). Different P sources were collected from Finland, Sweden and

Germany and their suitability for agricultural use was evaluated. Here we focused on the total

concentrations of heavy metals in relation to the present EU legislation, although solubility and

bioavailability determines more accurately the risk for the environment and people (e.g. Bolan et al.

2004). In addition to the heavy metals (Cd, Cu, Hg, Ni, Pb, Zn) regulated by EU’s Sewage Sludge

Directive, also Cr, As, Co and U were included in the study. Cr is regulated by national legislation in

Finland, Germany and Sweden, whereas As is regulated only in Finnish legislation among these three

countries (Ylivainio and Turtola 2016). At present there is no limit value for U concentrations in

fertilizers, although its concentration in inorganic P fertilizers can be elevated (Kratz et al. 2016) and

P fertilization can increase U concentrations in soils (Rogasik et al. 2008). In this report differences in

concentrations between various materials are discussed together with the effectiveness of the ASH

DEC –procedure to reduce the heavy metal contents in SSA.

3. Material and methods

3.1 Sampling

The sampled materials were various manures (dairy cattle, pig and poultry), digestates (derived from

manure and sewage sludge), liquid P sources, struvite (from Germany) and ASH DEC -product.

Struvite is a magnesium-ammonium-phosphate product from precipitation of dissolved P with

magnesium compounds (Egle et al. 2015).

Total of 27 digestion plants from Finland (13 plants), Sweden (6) and Germany (8) were sampled. The

distribution of plants according to manure types used as substrate is described by Bloem and

Lehmann (2016). From each biogas plant samples were taken before anaerobic digestion, from the

reactor or right after the reactor and from the end-products that were ready to be spread to the

fields. However, heavy metal contents were analyzed only from the samples allowed to be spread to

agricultural fields as P sources. Thus e.g. undigested sewage sludge samples and samples taken from

reactor were excluded from heavy metal analyses. Manure derived digestates also often had

different kinds of plant materials and industrial waste streams as feeding materials. The total

amount of samples was 70 including mineral P fertilizer (superphosphate) as a reference P source.

Raw material (apatite) used for producing superphosphate originated from Siilinjärvi mine (Finland).

In order to evaluate the effect of ASH DEC -process in reducing heavy metal concentrations in SSAs,

samples were taken from different process steps. First step was the gasification of the sewage

sludge to get sewage sludge ash (SSA) for the ASH DEC –treatment, in which SSA with specific

additives was treated in a rotary kiln at high temperatures. Before the treatment in the rotary kiln

SSA was sieved >630 µm to separate the bed material from the SSA. The process is described in

detail by Hermann and Schaaf (2016). First sample was taken from the sludge used in the ASH DEC –

process, second from dried sewage sludge (same as previous, but dried), third from the SSA, fourth

from sieved (>630 µm) SSA and fifth from the ASH DEC –product.


7

3.2 Determination of heavy metals

Heavy metal analyses were done from dried (at 37 °C in temperature controlled cabinet) and ground

(with a ball mill) samples to ensure homogeneity of the samples. Samples were digested with aqua

regia and heavy metal (As, Cd, Cr, Cu, Ni, Pb, Zn, Co) concentrations in the extracts were analyzed

with ICP-OES (Thermo Jarrel Ash Iris Advantage) and U by analyzing 238U isotope with high resolution

sector field ICP-MS (Element XR, Thermo). Part of the Hg measurements were done from aqua regia

extracts with Varian Cetac M-6000 A Mercury Analyzer, but due to the equipment failure, rest of the

Hg determinations were done directly from the air-dried samples by Teledyne Hydra IIc according to

the EPA 7473 method. The comparability of Hg determinations with two different methods was

checked by analyzing four samples with both methods. According to this comparison EPA 7473

method gave higher (53% at the highest) concentrations. However, all Hg concentrations were very

low being well below limit values set by EU and thus differences between two different methods can

be considered to be negligible. Duplicates were done frequently to ensure reliability of the results.

Dry matter contents (105 °C) were determined in three replicates.

4. Results

4.1 Heavy metal concentrations in P sources

Studied P sources were grouped as described in Table 1. One digestate contained pig slurry, sewage

sludge and biowastes. This digestate was included in solid digestates, not in sludges. Heavy metal

concentrations were calculated per P kilogram (Fig 1) and mineral P fertilizer, superphosphate, was

used as a reference P source. In addition, heavy metal loads per hectare were calculated using P

fertilizing rate of 10 kg ha-1 (Table 3). Heavy metal concentrations in dry matter (DM) are presented

in Appendices I and II.

Table 1. Grouping of studied P sources.

Abbreviation Description

Cattle Cattle manures and slurries Pig Pig manures and slurries Poultry Poultry manures Cattle and pig Mixture of cattle and pig manure Digestates (s) Solid fraction of biogas digestates derived from

manure Digestates (l) Liquid fraction of biogas digestates derived from

manure Sludge (s) Solid sewage sludge including both digested and

composted sludges Sludge (l)* Liquid fraction after centrifugation and struvite

precipitation of digested sludge Struvite Magnesium-ammonium-phosphate ASH DEC –product Product from Outotec’s thermochemical ASH

DEC –treatment *Due to the low dry matter content of the liquid, the sample amount wasn’t enough for dry matter analysis after heavy

metal determinations and thus the results are calculated on air-dried basis unlike in the other samples where results are on

a dry matter basis.


8

Variation of heavy metal concentrations within the same group of studied P sources were quite large

reflecting the heterogeneity of the materials (Fig. 1, Appendices I-II). Due to this large variation,

differences between countries with few exceptions were not observed (Appendices I-II). Because of

the variation and limited number of samples in some specific sample groups, results per P kilogram

from the same sample group were pooled (Fig. 1). However, some trends can be though seen in the

results.

Generally within the studied P sources (excluding ASH DEC-product), Zn, Cu, Cr and Ni were the most

abundant heavy metals, with the mean concentrations of 27, 7, 0.8 and 0.4 g kg-1 P, respectively

(Table 2). The rarest heavy metals were Hg and Cd with the mean concentrations of 5 and 17 mg kg-1

P, respectively (Table 2). In comparison, the most abundant heavy metals in superphosphate used as

a reference material were Cu, Zn, Cr and Pb, with the mean concentrations of 1.4, 1.1, 0.08, 0.06 g

kg-1 P, respectively (Table 2). Among the European mineral P fertilizers, studied superphosphate had

much lower Zn, Cr, Cd, Ni and As concentrations per P kilogram, whereas Pb concentration was at

the same level (Nziguheba and Smolders, 2008). The rarest heavy metal in superphosphate was Hg

(Table 2). Struvite together with superphosphate and sludge (l) had most often the lowest heavy

metal concentrations (Fig. 1). Among all the studied P sources, sludge (l) had though one of the

highest As (126 mg kg-1 P) and Ni (498 mg kg-1 P) concentrations. Related to struvite, only Pb and Hg

concentrations were slightly higher than in superphosphate (Fig. 1). However, it must be noticed

that in this study only one struvite, sludge (l) and superphosphate sample was studied.

In manures, the most abundant heavy metals were Zn and Cu, whereas Pb, As and Hg concentrations

were often under the detection limits (Fig. 1, Appendix I). In general, manures contained more heavy

metals per kilogram of P than superphosphate, with the exceptions of Cd and U, which were at the

same level (Table 2). Compared to solid sludges, manures contained, in average, less heavy metals

per P kilogram with the exception of Zn (Table 2). Heavy metal concentrations varied largely among

different animal types reflecting different feeding systems. Concentrations of Zn and Cu between

different manures followed the same pattern as found by Nicholson et al. (1999) in England and

Wales: The concentrations decreased in the following order: pig > poultry > cattle manures (Fig. 1,

Appendix I). In Swedish pig and poultry manure Zn concentration was higher than in the other

countries (Appendix I). Also Swedish cattle and pig manure mixture contained more Zn, Cu and Cd

than German one, whereas German mixture contained more Pb and Cr (Appendix I). However, only

one cattle and pig manure mixture sample was studied from both countries. In general, heavy metal

(Zn, Cu, Cd, Pb, Cr, Ni, As, Hg) concentrations (mg kg-1 DM) in different manures were lower or at the

same level as reported by Nicholson et al (1999) and Amlinger et al. (2004). When calculated per P

kilogram, only Hg concentration in cattle manures was above the values reported by McBride and

Spiers (2001). In pig manures mean Zn, Cu, Cd, Pb and Ni concentrations in relation to the P content

were lower and Cr concentration higher than reported by Kumaragamage et al. (2016). Compared to

the studies by Moore et al. (1998) and Ihnat and Fernandes (1996), only P related Cr concentration

in poultry manure were higher, whereas Zn, Cu, Cd, Pb, Ni and As concentrations were either under

the values reported or at the same level. Mean U concentration in manures (cattle 0.27, pig 0.55,

poultry 0.82 mg kg-1 DM) were at the same level with the study by Kratz et al. (2008), where U

concentration in cattle manure ranged from 0.03 to 2.8, in pig manure from 0.05 to 11.1 and in

poultry manure from 0.19 to 11.6 mg kg-1 DM. When manures are used as a P fertilizer at

fertilization rate of 10 kg P ha-1, highest heavy metal loads come from Zn, Cu, Cr, Ni and Pb (Table 3).


9

Solid sludges contained more heavy metals per kilogram of P than superphosphate (Fig. 1, Table 2).

The most abundant heavy metals in solid sludges were Zn, Cu, Cr, Ni, U and Pb (Table 2, Fig. 1).

German solid sludges contained more Zn, Pb and Cr (mg kg-1 DM) than Finnish and Swedish sludges

(Appendix II). The large variation in Cr concentration of German solid sludges results from one

sample with exceptionally high Cr concentration (664 mg kg-1 DM). Concentrations of Zn, Cu, Cd, Pb,

Cr, Ni and Hg in dry matter basis were at the range reported in EU countries (Amlinger et al. 2004).

Concentration of U varied largely between countries, concentration being highest in Sweden (mean

1072 mg kg-1 P, variation 358-2335 mg kg-1 P) and Finland (mean 593 mg kg-1 P, variation 72.9-1565

mg kg-1 P)(Fig. 1, Appendix II). Most probably this is due to high U concentrations in bedrock, soils

and groundwater in specific areas in Sweden and Finland. Weathering of bedrock releases natural

radionuclides to soil and thus the highest aqua regia –soluble U concentrations in European

agricultural soils are found in Sweden, Portugal and Finland (Reimann et al. 2014).

Table 2. Mean heavy metal concentrations in manures, solid sludges, average for all studied P

sources, ASH DEC-product and Siilinjärvi superphosphate (g kg-1 or mg kg-1 of P in the material).

Standard deviation is presented in parenthesis.

g kg-1 P mg kg-1 P

Zn/P Cu/P Cd/P Pb/P Co/P Cr/P Ni/P As/P Hg/P U/P

Manures (n*

=26) 32.3 (17.8)

7.6 (7.1)

15.2 (7.0)

162 (124)

120 (67)

377 (205)

303 (170)

51.2 (23.0)

3.4 (1.7)

42.5 (44.2)

Sludge (s) (n=12)

18.4 (4.6)

10.0 (2.7)

22.3 (3.4)

529 (142)

250 (163)

2501 (5417)

713 (210)

124 (81)

12.2 (2.9)

683 (793)

All studied P sources** (n=68)

26.5 (14.6)

7.0 (5.4)

17.2 (6.9)

261 (212)

151 (97.8)

780 (2272)

406 (233)

64.1 (55.8)

5.1 (4.0)

151 (408)

ASH DEC-product (n=1)

27.2 14.3 4.3 892 187 59898 31436 82.4 <0.02 73.5

Siilinjärvi superphosphate (n=1)

1.1 1.4 13.7 57.1 24.7 82.0 17.9 12.2 0.1 38.4

*n is number of samples

**excluding superphosphate and ASH DEC-product

Table 3. Heavy metal loads (g ha-1) with P fertilization rate of 10 kg ha-1.

Zn Cu Cr Cd Pb Co Ni As Hg U

Cattle 225 52 3 0 2 2 3 1 0 0 Poultry 304 54 4 0 1 1 3 1 0 1 Pig 453 148 4 0 1 1 3 0 0 0 Cattle and pig 527 106 5 0 3 1 3 0 0 0 Sludge (s) 184 100 25 0 5 2 7 1 0 7 Digestates (s) 267 61 5 0 2 1 4 0 0 0 Digestates (l) 236 44 4 0 2 1 4 1 0 0 Sludge (l) 39 12 1 0 0 1 5 1 0 0 Struvite 4 3 1 0 1 0 0 0 0 0 Superphosphate 11 14 1 0 1 0 0 0 0 0 ASH DEC 272 143 599 0 9 2 314 1 0 1


10

According to Reimann et al. (2014) European agricultural soils contain 0.77 mg U kg-1 DM (median,

range <0.04-24 mg kg-1 DM, n=2108) and permanent grasslands 0.74 mg kg-1 (median, range 0.047-

73 mg kg-1 DM, n=2024). In contrast to northern Europe, U concentration in agricultural soils of

central Europe are low (Reimann et al. 2014), which may explain much lower U concentration in

studied German solid sludge sample (52 mg kg-1 P) compared to those taken from Finland and

Sweden. However, in this study U was analyzed only from one German solid sludge sample. From

soil and bedrock, U dissolves to water for household consumption, which finally ends up to sewage

water treatment plants. According to Lahermo et al. (2002), mean U concentration in Finnish

manmade shallow wells (n=739) is 0.846 µg l-1, maximum being 36.6 µg l-1, whereas in drilled

bedrock wells (n=263) mean concentration is 13.7 µg l-1 maximum being 643 µg l-1. Locally

concentrations can be much higher and U concentration as high as 15 mg l-1 is found in wells drilled

in bedrock in Helsinki region (Åström et al. 2009). This spatial variation may explain the large

variation in U concentrations in Finnish solid sludges. The maximum concentrations in Finnish (52 mg

kg-1 DM) and Swedish solid sludges (75 mg kg-1 DM) are higher than maximum value in German

sewage sludges (18 mg kg-1 DM) reported by Kratz et al. (2008).

When solid sludges are used as a P-fertilizer with fertilizing rate of 10 kg P ha-1, highest heavy metal

loads come from Zn, Cu, Cr (Table 3). Average U load is 7 g ha-1, which is more than evaluated by

Kratz et al. (2008) for sewage sludges (mean 3.2 g ha-1, range 0.001-19 g ha-1, P rate 22 kg ha-1) but is

within the range of mineral P fertilizers. Also the maximum loads (16 g ha-1 in Finland and 23 g ha-1 in

Sweden) are within the range of U loads from mineral P fertilizers (Kratz et al. 2008).

Among the solid and liquid digestates, Zn, Cu, Cr and Ni had the highest concentrations and only U

concentrations were lower than in superphosphate (Fig. 1). German liquid digestates contained

more Zn, Cu, Cd, Cr and As than the Finnish ones (Appendix II).

For the ASH DEC-product, only Cd and Hg concentrations were lower than in superphosphate (Fig. 1,

Table 2) and the main heavy metals were Cr, Ni, Zn and Cu (Fig. 1, Table 3). However, exceptionally

high Cr and Ni concentrations result from the technical problem encountered in the process as

discussed in the following chapter.


11

Fig.1. Heavy metal concentrations (±SD) in studied P sources and in Siilinjärvi superphosphate

calculated per kilogram of P. Number of samples is presented in parenthesis. Abbreviations: s = solid

fraction, l = liquid fraction, × = result of one deviating sewage sludge sample.

0102030405060708090

g Z

n k

g-1

P

05

101520253035

g C

u k

g-1

P

02468

101214161820

g C

r k

g-1

P 59.9

0

5

10

15

20

25

30

35m

g C

d k

g-1

P

0100200300400500600700800900

1000

mg

Pb

kg

-1 P

050

100150200250300350400450500

mg

Co

kg

-1P


12

Fig. 1. Continues.

4.2 ASH DEC-process

As described in chapter 4.1 the main heavy metals in ASH DEC-product were Cr (3.5 g kg-1 DM), Ni

(1.9 g kg-1 DM), Zn (1.6 g kg-1 DM) and Cu (0.8 g kg-1 DM). Along the process heavy metal

concentrations decreased (except Ni) during gasification and increased after sieving the most bed

material away (except Ni) meaning that the bed material diluted the concentrations during the

gasification (Fig. 2). ASH DEC-process reduced Cd (59%) and Hg (from 0.3 to <0.02 mg kg-1 DM)

concentrations compared to sewage sludge used as feeding material. On the contrary, Cr and Ni

concentrations were elevated due to the corrosive attack of sewage sludge on unprotected steel

walls of the reactors in the reducing conditions (Hermann and Schaaf 2016). When produced in

industrial scale, however, corrosion is easily overcome by protecting the reactor walls by refractory

material (Hermann and Schaaf 2016).

31 4360

500100015002000250030003500400045005000

mg

Ni

kg

-1P

0255075

100125150175200225

mg

As

kg

-1 P

02468

101214161820

mg

Hg

kg

-1P

0100200300400500600700800900

1000

mg

U k

g-1

P


13

Fig. 2. Heavy metal concentrations (mg kg-1 DM) along the ASH DEC -process. SSA is sewage sludge

ash.

0

500

1000

1500

2000

2500

3000

3500

4000

Zn Cu Cr Ni

mg

kg

-1D

M

Sludge Sludge. dried with warm air SSA >630 SSA ASHDEC product

0

10

20

30

40

50

60

Cd Pb Co As Hg U

mg

kg

-1D

M

Sludge Sludge. dried with warm air SSA >630 SSA ASHDEC product


14

5. Conclusions Variation in heavy metal concentrations was large within the same manure type and other group of

P sources. Despite of this large variation, some trends could be seen in the results. Among all studied

P sources, Zn, Cu, Cr and Ni were the most abundant heavy metals, whereas Hg and Cd were the

rarest. For manures, Zn and Cu concentrations were highest in pig manures and lowest in cattle

manures. In Swedish pig and poultry manure Zn concentration was higher than in the other

countries. Compared to the superphosphate, manures contained more heavy metals per kilogram of

P with the exceptions of Cd and U. However, manures contained mostly less heavy metals than the

solid sludges. Compared to the literature, P related heavy metal concentrations were mostly at the

same level, only Hg content in cattle manures and Cr content in pig and poultry manures were

higher.

Heavy metal concentrations in solid sludges were higher than in superphosphate and the most

abundant heavy metals were Zn, Cu, Cr, Ni, U and Pb. Concentrations were at the range reported in

the EU. Uranium concentrations were higher in Swedish and Finnish sludges possibly due to the

geology of these areas. At present, studies about uranium in sewage sludges and other organic P

sources are scarce and the issue should be studied further.

In both solid and liquid fractions of manure derived digestates the main heavy metals were Zn, Cu,

Cr and Ni and only U concentrations were lower than in superphosphate. Struvite, liquid fraction of

sludge and superphosphate had most often the lowest heavy metal concentrations.

ASH DEC –process reduced Cd and Hg concentrations compared to the sewage sludge used as a

feeding material, whereas Cr and Ni contents increased due to the corrosion of unprotected steel

reactor walls of test equipment in contrast to refractory lined reactor walls of industrial equipment.


15

6. References Amlinger, F., Pollak, M. and Favoino, E. 2004. Heavy metals and organic compounds from wastes

used as organic fertilizers. ENV.A.2./ETU/2001/0024. Final report.

http://ec.europa.eu/environment/waste/compost/pdf/hm_finalreport.pdf

Bastian, R.K., Bachmaier, J.T., Schmidt, D.W., Salomon, S.N., Jones, A., Chiu, W.A., Setlow, L.W.,

Wolbarst, A.B., Yu, C., Goodman, J. and Lenhart, T. 2005. Radioactive Materials in Biosolids: National

Survey, Dose Modeling, and Publicly Owned Treatment Works (POTW) Guidance. Journal of

Environmental Quality 34: 64-74.

Bloem, E. and Lehmann, L. 2016. Report on contamination of P-rich waste materials with organic

xenobiotics. BONUS Promise deliverable 2.2. 15p.

Bolan, N.S., Adriano, D.C. and Mahimairaja, S. 2004. Distribution and bioavailability of trace

elements in livestock and poultry manure by-products. Critical Reviews in Environmental Science and

Technology 34:291–338.

Cooper, J., Lombardi, R., Boardman, D. and Carliell-Marquet, C. 2011. The future distribution and

production of global phosphate rock reserves. Resources, Conservation and Recycling 57: 78–86.

Cordell, D., Drangert, J-O. and White, S. 2009. The story of phosphorus: Global food security and

food for thought. Global Environmental Change 19: 292–305.

Egle, L., Rechberger, H. and Zessner, M. 2015. Overview and description of technologies for

recovering phosphorus from municipal wastewater. Resources, Conservation and Recycling 105:

325–346.

EPA 7473. Mercury in solids and solutions by thermal decomposition amalgamation and atomic

absorption spectrometry. 17p.

European Commission 2010. Environmental, economic and social impacts of the use of sewage

sludge on land. Final report. Part III: Project Interim Reports.

http://ec.europa.eu/environment/archives/waste/sludge/pdf/part_iii_report.pdf.

Havukainen, J., Nguyen, M.T., Hermann, L., Horttanainen, M., Mikkilä, M., Deviatkin, I. and Linnanen,

L. 2016. Potential of phosphorus recovery from sewage sludge and manure ash by thermochemical

treatment. Waste Management 49: 221–229.

Hermann, L. and Schaaf, T. 2016. Report on thermo-chemical processing of organic P-rich waste

materials. BONUS Promise deliverable 3.1. 14p.

Herzel, H., Krüger, O., Hermann, L. and Adam, C. 2016. Sewage sludge ash — A promising secondary

phosphorus source for fertilizer production. Science of the Total Environment 542: 1136–1143

Hukari, S., Hermann, L. and Nättorp, A. 2016. From wastewater to fertilisers — Technical overview

and critical review of European legislation governing phosphorus recycling. Science of the Total

Environment 542: 1127–1135.


16

Ihnat, M. and Fernandes, L. 1996. Trace elemental characterization of composted poultry manure.

Bioresource Technology 57: 143-156.

Jiménez, F., Debán, L., Pardo, R., López, R. and García-Talavera, M. 2011. Levels of 131I and Six Natural

Radionuclides in Sludge from the Sewage Treatment Plant of Valladolid, Spain. Water, Air & Soil

Pollution 217:515–521.

Kelessidis, A. and Stasinakis, A.S. 2012. Comparative study of the methods used for treatment and

final disposal of sewage sludge in European countries. Waste Management 32: 1186–1195.

Kratz, S., Knappe, F., Rogasik, J. and Schnug, E. 2008. Uranium balances in agroecosystems. In: De

Kok, L. J. and Schnug, E. (eds.). 2008. Loads and Fate of Fertilizer-derived Uranium. Backhuys

Publishers, Leiden, The Netherlands. 219p.

Kratz, S., Schick, J. and Schnug, E., 2016. Trace elements in rock phosphates and P containing mineral

and organo-mineral fertilizers sold in Germany. Science of The Total Environment 542: 1013-1019.

Krüger, O. and Adam, C. 2015. Recovery potential of German sewage sludge ash. Waste

Management 45: 400–406.

Kumaragamage, D., Akinremi, O.O. and Racz, G.J. 2016. Comparison of Nutrient and Metal Loadings

with the Application of Swine Manure Slurries and Their Liquid Separates to Soils. Journal of

Environmental Quality 45:1769–1775.

Lahermo, P, Tarvainen, T., Hatakka, T. Backman, B., Juntunen, R., Kortelainen, N., Lakomaa, T.,

Nikkarinen, M., Vesterbacka, P., Väisänen, U. and Suomela, P. 2002. Tuhat kaivoa – Suomen

kaivovesien fysikaalis-kemiallinen laatu vuonna 1999. Summary: One thousand wells – the physical-

chemical quality of Finnish well waters in 1999. Geological Survey of Finland. Report of Investigation

155. 92p.

McBride, M.B. and Spiers, G. 2001. Trace element content of selected fertilizers and dairy manures

as determined by ICP-MS. Communications in Soil Science and Plant Analysis 32: 139-156.

Moore, P.A.Jr., Daniel, T.C., Gilmour, J.T., Shreve, B.R., Edwards, D.R. and Wood, B.H. 1998.

Decreasing metal runoff from poultry litter with aluminium sulfate. Journal of Environmental Quality

27: 92-99.

Nziguheba, G. and Smolders, E., 2008. Inputs of trace elements in agricultural soils via phosphate

fertilizers in European countries. Science of The Total Environment 390: 53-57.

Nicholson, F.A., Chambers, B. J., Williams, J.R and Unwin, R.J. 1999. Heavy metal contents of

livestock feeds and animal manures in England and Wales. Bioresource Technology 70: 23-31.

Poulsen, H.D. 1998. Zinc and copper as feed additives, growth factors or unwanted environmental

factors. Journal of Animal and Feed Sciences 7: 135-142.

Reimann, C., Demetriades, A., Birke, M., Filzmoser, P., O’Connor, P., Halamic, J., Ladenberger, A. and

the GEMAS Project Team 2014. Distribution of elements/parameters in agricultural and grazing land

soil of Europe. Uranium (U). In: Reimann, C., Birke, M., Demetriades, A., Filzmoser, P. and O’Connor,


17

P. (eds.). 2014. Chemistry of Europe’s agricultural soils. Part A. Methodology and interpretation of

the GEMAS data set. Geologisches Jahrbuch, Reihe B, Heft 102. 528p.

Rogasik, J., Kratz, S., Funder, U., Panten, K., Barkusky, D., Baumecker, M., Gutser, R., Lausen, P.,

Scherer, H.W., Schmidt, L. and Schnug, E. 2008. Uranium in soils of German long-term fertilizer

experiments. In: De Kok, L. J. and Schnug, E. (eds.). 2008. Loads and Fate of Fertilizer-derived

Uranium. Backhuys Publishers, Leiden, The Netherlands. 219p.

Sheppard, S.C, Long, J.M. and Sanipelli, B. 2010. Verification of radionuclide transfer factors to

domestic-animal food products, using indigenous elements and with emphasis on iodine. Journal of

Environmental Radioactivity 101: 895-901.

Sheppard, S.C. and Sanipelli, B. 2012. Trace Elements in feed, manure and manured soils. Journal of

Environmental Quality 41: 1846-1856.

Sörme, L. and Lagerkvist, R. 2002. Sources of heavy metals in urban wastewater in Stockholm. The

Science of the Total Environment 298: 131–145.

Van Dijk, K. C., Lesschen, J.P. and Oenema, O. 2016. Phosphorus flows and balances of the European

Union Member States. Science of the Total Environment 542:1078–1093.

Ylivainio, K., Sarvi, M., Lemola, R., Uusitalo, R., and Turtola, E. 2014. Regional P stocks in soil and in

animal manure as compared to P requirement of plants in Finland. MTT Report 124. 35p.

http://www.mtt.fi/mttraportti/pdf/mttraportti124.pdf.

Ylivainio, K. and Turtola, E. 2016. Report on specifications of waste materials to be suitable for

recycling. BONUS Promise Deliverable 3.2. 11p.

Åström, M. E., Peltola, P., Rönnback, P., Lavergren, U., Bergbäck, B., Tarvainen, T., Backman, B. and

Salminen, R. 2009. Uranium in surface and groundwaters in Boreal Europe. Geochemistry:

Exploration, Environment, Analysis 9: 51-62.


18

Appendix I. Heavy metal concentrations (mg kg-1 in dry matter) in manures and solid sludges (sludge

(s)) sampled from different countries (±SD). Dotted line shows respective concentration in mineral P

fertilizer (superphosphate) originating from Siilinjärvi, Finland.

0

100

200

300

400

500

600

700

Cat

tle

Po

ult

ry Pig

Cat

tle

and

pig

Slu

dge

(s)

Cu

mg

kg

-1

0

200

400

600

800

1000

1200

1400

1600

Cat

tle

Po

ult

ry Pig

Cat

tle

and

pig

Slu

dge

(s)

Zn

mg

kg

-1

FINLAND

SWEDEN

GERMANY

Superphosphate

0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.4

Cat

tle

Po

ult

ry Pig

Cat

tle

and

pig

Slu

dge

(s)

Cd

mg

kg

-1

0

5

10

15

20

25

30

35

Cat

tle

Po

ult

ry Pig

Cat

tle

and

pig

Slu

dge

(s)

Pb

mg

kg

-1


19

0

10

20

30

40

50

60

70

80

90

100

Cat

tle

Po

ult

ry Pig

Cat

tle

and

pig

Slu

dge

(s)

Cr

mg

kg

-1

343

0

5

10

15

20

25

30

35

Cat

tle

Po

ult

ry Pig

Cat

tle

and

pig

Slu

dge

(s)

Ni

mg

kg

-1

0

1

2

3

4

5

6

7

8

Cat

tle

Po

ult

ry Pig

Cat

tle

and

pig

Slu

dge

(s)

As

mg

kg

-1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Cat

tle

Po

ult

ry Pig

Cat

tle

and

pig

Slu

dge

(s)

Hg

mg

kg

-1

0

5

10

15

20

25

30

35

40

Cat

tle

Po

ult

ry Pig

Cat

tle

and

pig

Slu

dge

(s)

U m

g k

g-1

0

2

4

6

8

10

12

14

16

18

20C

attl

e

Po

ult

ry Pig

Cat

tle

and

pig

Slu

dge

(s)

Co

mg

kg

-1

FINLANDSWEDENGERMANY


20

Appendix II. Heavy metal concentrations (mg kg-1 in dry matter) in sludges, digestates and struvite

sampled from different countries (±SD). Dotted line shows respective concentration in mineral P

fertilizer (superphosphate) originating from Siilinjärvi, Finland. Abbreviations: s = solid, l = liquid.

0

100

200

300

400

500

600

700

Slu

dge

(s)

Slu

dge

(l)

Stru

vite

Dig

esta

tes

(s)

Dig

esta

tes

(l)

Cu

mg

kg

-1

0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.4

Slu

dge

(s)

Slu

dge

(l)

Stru

vite

Dig

esta

tes

(s)

Dig

esta

tes

(l)

Cd

mg

kg

-1

0

5

10

15

20

25

30

35

Slu

dge

(s)

Slu

dge

(l)

Stru

vite

Dig

esta

tes

(s)

Dig

esta

tes

(l)

Pb

mg

kg

-1

0

200

400

600

800

1000

1200

Slu

dge

(s)

Slu

dge

(l)

Stru

vite

Dig

esta

tes

(s)

Dig

esta

tes

(l)

Zn

mg

kg

-1

FINLANDSWEDENGERMANYSuperphosphate


21

0

2

4

6

8

10

12

14

16

Slu

dge

(s)

Slu

dge

(l)

Stru

vite

Dig

esta

tes

(s)

Dig

esta

tes

(l)

Co

mg

kg

-1

FINLANDSWEDENGERMANYSuperphosphate

0

5

10

15

20

25

30

35

40

Slu

dge

(s)

Slu

dge

(l)

Stru

vite

Dig

esta

tes

(s)

Dig

esta

tes

(l)

Cr

mg

kg

-1

0

5

10

15

20

25

30

35

Slu

dge

(s)

Slu

dge

(l)

Stru

vite

Dig

esta

tes

(s)

Dig

esta

tes

(l)

Ni

mg

kg

-1

0

1

2

3

4

5

6

7

8

Slu

dge

(s)

Slu

dge

(l)

Stru

vite

Dig

esta

tes

(s)

Dig

esta

tes

(l)

As

mg

kg

-1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Slu

dge

(s)

Slu

dge

(l)

Stru

vite

Dig

esta

tes

(s)

Dig

esta

tes

(l)

Hg

mg

kg

-1

0

5

10

15

20

25

30

35

Slu

dge

(s)

Slu

dge

(l)

Stru

vite

Dig

esta

tes

(s)

Dig

esta

tes

(l)

U m

g k

g-1

report on environmentally relevant heavy metals in p-fertilizer … · 2017-07-04 · report on...

Documents