This is an archive post-print (ie final draft post-refereeing)

Please cite this scientific paper as:

Beauchamp, C.J., Charest, M.-H. and Gosselin,, A. 2002. Examination of

environmental quality of raw and composting de-inking paper sludge. Chemosphere

46(6) : 887-895.

For PDF : https://doi.org/10.1016/S0045-6535(01)00134-5

EXAMINATION OF ENVIRONMENTAL QUALITY OF RAW AND COMPOSTING

DE-INKING PAPER SLUDGE

Chantal J. Beauchamp*, Marie-Hélène Charest and André Gosselin

Département de phytologie, Université Laval, Sainte-Foy, QC, CANADA, G1K 7P4

*Corresponding author : Chantal J. Beauchamp

E-mail: Chantal.Beauchamp@plg.ulaval.ca

Tel.: (418) 656-2131 extension 7349

Fax: (418) 656-7856

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ABSTRACT

The paper sludges were traditionally landfilled or burned. Over the years, the use of

paper sludges on soils has increased, as well as the concerns about their

environmental effects. Therefore, the chemical characterization of paper sludges and

their young (immature) compost needed to be investigated, and over 150 inorganic

and organic chemicals were analyzed in de-inking paper sludge (DPS). In general,

nitrogen, phosphorus and potassium contents were low but variable in raw DPS and

its young compost. Their contents in arsenic, boron, cadmium, cobalt, chromium,

manganese, mercury, molybdenum, nickel, lead, selenium and zinc were also low

and showed low variability. However, their contents in copper were above the

Canadian compost regulation for unrestricted use and required a follow up. The fatty

and resin acids, and polycyclic aromatic hydrocarbons were the organic chemicals

measured at the highest concentrations. For resinic acids, care should be taken to

avoid that leachates reach aquatic life. For polycyclic aromatic hydrocarbons,

naphthalene should be followed until soil content reaches 0.1 µg g-1, the maximum

allowed for soil use for agricultural purposes according to Canadian Environmental

Quality Guidelines. In young compost, the concentration of these chemical families

decreased over time and most compounds were below the detection limits after 24

weeks of composting. In raw DPS, among the phenol, halogenated and

monoaromatic hydrocarbon, dioxin and furan, and polychlorinated biphenyl families,

most compounds were below the detection limits. The raw DPS and its young

compost do not represent a major threat for the environment but can require an

environmental follow up.

Keywords: copper, resin acids, polycyclic aromatic hydrocarbons

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1. INTRODUCTION

Currently, solid wastes of pulp and paper origin are disposed of through

combustion or landfilling. In Canada in 1995, these solid wastes represented 7.1 dry

Mt/a of which 2.9 dry Mt/a were available for use instead of been landfilled or

burned (Reid 1997). For the Quebec province only, about 1.2 dry Mt/a were produced

in 1999 of which 0,8 dry Mt/a were available for use (unpublished data, MEF 1999).

These wastes included wood and bark, sludges, ash and recausting, and

miscellaneous residues.

The sludges can be divided into several categories; the wastepaper coming

from the production of virgin wood fiber, called primary sludge; the wastepaper

produced by removing inks from post-consumer fiber, called paper de-inking sludge

(DPS); the activated sludge from the secondary treatment systems, called secondary

sludge; and combined wastepaper and activated sludge, called combined sludges. Of

the total solid wasted produced by the whole Canadian industry, 42% are primary

sludge, 12% de-inking sludge, 26% are secondary sludge, and 18% are combined

sludge (Reid 1997).

DPS has been selected for this study since it should contain more contaminants

than other sludges. DPS contains to a lower extent, minerals such as clays and chalks,

and chemical additives added during the manufacture of paper, printing and

recycling. Among the organic contaminants reported in paper sludges, the dioxins,

polychlorinated biphenyls (PCBs), volatile organic priority pollutants, phenols, fatty

and resin acids have been mentioned (NCASI 1991; CQVB 1996; Bellamy et al. 1995).

The paper sludges can be used to improve soil properties since they contain

mainly carbon (C); thus, they can have beneficial effects on soils that are deficient in

organic matter. Some paper sludges have been used in agriculture, as soil

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amendment, since the mid-forties (NCASI 1959). DPS contains about 45 to 85%

organic carbon, such as short cellulose fibers (Latva-Somppi et al. 1994). However,

raw DPS, similar to most fresh organic matter, immobilizes temporary soil nitrogen

(N) and phosphorus (P) since its C : N ratio and C : P ratio are high (Fierro et al. 1997).

Compost is the product of degradation of fresh organic matters by

microorganisms responsible for the increase in temperature from about 55 to 70°C.

The sugars, cellulose and hemicellulose fractions of DPS are normally degraded in the

first step of composting followed by the lignin fraction in the last step (Brouillette et

al. 1996). At that stage, the temperature of the compost should be in the mesophilic

range (45 to 10°C) and its organic matter should be stabilized. Addition of stabilized

compost to soil should not immobilize soil nutrients that can be an advantage

compared to raw DPS.

For composting, water, C, N, phosphorus (P) and potassium (K) contents of

wastes should be considered, as well as their availability to microbes involved in the

decomposition process (Mustin 1987). Raw DPS has a moisture content higher than

50% water and poorly biodegradable carbon (Chantigny et al. 1999). Animal slurries

contain more than 90% moisture and N, P and K available to feed the trophic chain. It

has been observed that raw DPS can absorb up to 70-75% liquid and, thereafter,

leaching occurs. For ligno-cellulose wastes, the addition of organic nitrogen without

reaching a C : N ratio of 25 is acceptable (Mustin 1987), as long as an increase in

temperature indicates that the composting process is underway. The P content should

be between 0.2 and 1.0%, and K content between 0.2 and 0.5%.

Using animal slurries in sequence, to avoid important leaching and to correct

the nutrients available to several microbe generations, appears an interesting avenue

for an integrated management of DPS and animal slurries that needed to be

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evaluated. However, concerns about the possible adverse effects of raw DPS and its

young or immature compost on the environment still remain. Therefore, an important

question to be addressed is the potential risk that raw DPS contains organic and

inorganic contaminants and the evolution of these contaminants during the

composting process. The goals of this study were to characterize the chemical

compounds present in raw DPS over a period of two years and to measure the

evolution of the chemical compounds in its young compost over a period of 24 weeks.

2. Materials and methods

2.1 Paper de-inking sludge characterization. The DPS came from a local de-inking

plant in Quebec City (Daishowa, QC, CANADA). The DPS were collected at about

four-month intervals for two years. At each sampling period, one day-truck out of

two was sampled for about two weeks and for a total of 25 trucks. For each truck, ten

subsamples were taken randomly with a 250 mL glass beaker to a 30 cm depth, mixed

in a 6 L glass flask, and then, one 500 mL glass container was filled per truck. The

glass containers were immediately put and kept in darkness at -4°C. A total of 25

glass containers were collected per sampling period. These containers were thawed

and one composite sample of 2 L was sent, on ice, to an external laboratory

(Novaman Ltée, Lachine, QC, CANADA) and analyzed.

The moisture content was measured after oven-drying DPS at 105 ˚C for 24 h.

The pH was measured in a 1 : 10 (v/v) DPS : water slurry (MEF, 1990). The total

carbon was determined by dry combustion method using an automated analyzer

(CHN, Carlos Erba, Milan, Italy). Standard procedures were used to convert

organically bound nitrogen to ammonia and the sum of free and converted-ammonia

were measured by colorimetric analysis/Skalar to determine the Total Kjeldahl

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nitrogen (N) (APHA 1989). The total elements were first obtained by the HNO3-HCl

wet digestion (EPA 3050: U.S. EPA 1986). Then, total phosphorus (P), potassium (K),

calcium (Ca), magnesium (Mg) and trace elements (arsenic (As), boron (B), cadmium

(Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn),

molybdenum (Mo), nickel (Ni), lead (Pb), selenium (Se) and zinc (Zn)) were obtained

by inductively coupled plasma/atomic emission spectroscopy (EPA 3050: U.S. EPA

1986; MEF 1990). Mercury (Hg) was measured by cold vapor atomic absorption

spectrometry (EPA 7471: U.S. EPA 1986). Resin and fatty acids were extracted using

dichloromethan and derived with N-O-bis-trimethylsyliltrifluoroacetamid (BSTFA)

before they were quantified by gas chromatography and mass spectrometry (GC/MS)

(MEF 1988). Polycyclic aromatic hydrocarbons were extracted using methyl-t-butyl-

ether (MTBE). The organic phases were dried on Na2SO4, concentrated and exchanged

by hexan (C6H14), and then, purified on a silica cartridge. Resin and fatty acids were

determined and quantified by gas chromatography and mass spectrometry (GC/MS)

(U.S. EPA 1986; MEF 1990). Also, volatile organic compounds, phenols and,

polychlorinated dibenzofurans and dibenzodioxins were analyzed by GC/MS and

polychlorinated biphenyls were analyzed by GC/ECD using standard methods (U.S.

EPA 1986; Environnement Canada 1990; MEF 1990).

2.2 Composting paper de-inking sludge. This study was undertaken in an area

having pig slurry surplus, and required a composting permit from the Quebec

Ministry of the Environment. The permit allowed only raw DPS and animal slurry or

manure on the experimental site. No other component was permitted.

The pile size and shape, and sequential addition of pig slurry and liquid

poultry manure were selected to allow the composting process under the cool and

7

humid conditions in north-eastern Canada. Trapezoid piles of about 250 m3 were

formed at a composting plant (Les Composts du Québec, Inc., Saint-Henri-de-Lévis,

QC, CANADA). They were 2.5 m high, 10 m wide and 10 m long with a depression

on the top to allow absorption of animal slurry or liquid manure by DPS and avoid

leaching.

Three replicated piles in time (one summer and two consecutive falls) were

formed with DPS (90% v/v), pig slurry and liquid poultry manure (10% v/v), and 3

kg of 26-13-13 (N-P2O

5-K

2O) per Mg DPS. To avoid important leaching, every

weekday, the piles were sprayed with pig slurry and during weekend with liquid

poultry manure for 24 weeks to decrease the C : N : P : K ratios over time. The pig

slurry and liquid poultry manure were obtained from five large farms growing pigs

and piglets, and broiler chicks in the Rivière-Appalache neighbourhood. The pig

slurry and liquid poultry manure were analyzed for their total elements in our

laboratory. The total elements were determined after wet digestion by HNO3-HCl.

Total N (Kjeldahl) was determined by distillation and titration (Horwitz 1980). The

other total elements were determined by flame emission or atomic absorption

spectrometry (EPA 3050; U.S. EPA 1986). Pig slurry contained only 0.6% dry matter

and 0.21% total N (dry weight; dw), 0.02% P (dw) and 0.07% K (dw). Only Fe was

measured at 19 µg g-1 (dw), whereas the other trace elements were below the

detection limits (B < 5 µg g-1, Cd < 1 µg g-1, Co < 2 µg g-1, Cr < 2 µg g-1, Cu < 5 µg g-

1, Mn < 5 µg g-1, Ni < 10 µg g-1, Pb < 20 µg g-1, Zn < 10 µg g-1). Liquid poultry

manure contained 1.6% dry matter and between 0.25 to 0.76% total N (dw), 0.08 to

0.25% P (dw) and 0.09 to 0.15% K (dw). Only Fe and Mn were measured at 21 and 7

µg g-1 (dw), respectively. The other trace elements were below the detection limits.

8

Piles were mechanically turned after two weeks of composting and thereafter

at every four weeks. To evaluate the composting process, the pile temperature was

recorded with a thermometer every week for four weeks and thereafter only once a

month. The piles were sampled after 0, 8, 16 and 24 weeks of composting and at more

than 40 random points at a depth of 30 cm, for a total of 10 L. These subsamples were

mixed in glass containers and one composite sample of 5 L was put in each glass

container. The composite sample was kept in darkness at 4°C and sent to an external

laboratory for analyses (Novaman Ltée, Lachine, QC, CANADA). The pH, total C, N

(CNS-1000 Leco), P, K, Ca, Mg and trace elements, fatty and resin acids, PAHs and

phenols, were analyzed as described above.

2.3 Statistical analyses. Means and standard deviations were calculated using

detection limits for non detectable compounds. When all data were under detection

limit, only this value was presented.

3. Results and discussion

3.1 Physical characteristics and nutrient elements of paper de-inking sludge and its

young compost. Raw DPS showed variability in total C, N, P, K, Ca and Mg (Table 1).

The high total C content of raw DPS is related to its content of wood fibers and

indirectly to its low clay content. The nutrient elements were low compared to

mineral fertilizers; in particular total N, P and K contents of raw DPS were likely to

be growth-limiting for microorganisms or plants.

After piles formation, temperature raised at about 55 to 60°C, that is typical of

paper sludge compost (Chong and Cline 1991) and indicated microbial activities and

that the composting process was underway. The temperature remained at about 60°C

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even during the winter periods where ambient temperatures were below 0°C.

Therefore, the composting process was underway. After 24 weeks of composting, the

temperature did not decrease, indicating that this compost was not mature. The pH

(Table 1) was representative of compost in the thermophilic stage (Crawford 1983)

and paper sludge compost (Campbell et al. 1995). The moisture content of

composting DPS was maintained in the optimum range of 50 to 70% (Crawford 1983).

The total C content, that was 44% at piles formation, decreased to 36% after 24

weeks of composting. The bioavailable C, for example, sugars and cellulose, was

transformed by microbes into CO2 and H2O, and resulted in the loss of organic matter

that concentrated nutrient contents. This slow decrease in total C underlined the poor

biodegradability of wood fibers in DPS. This resistance of DPS to decomposition

appears similar to newsprint (Lu et al. 1995) and increases the composting period

required to obtain mature compost.

The total N content increased from 0.1% to about 0.5% during the same period

of time, due to sequential addition of pig slurry and liquid poultry manure, and the

loss of organic matter. This resulted in a C : N ratio of 81 within 24 weeks of

composting, which is above the recommended ratio of 25 to 35 (Campbell et al. 1995;

Mustin 1987) but showed a similar trend to composted bark amended with urea,

where the initial C : N ratio of 155 decreased to 50 (Darbyshire et al. 1989).

The total P and K contents were about 0.2% within 24 weeks of composting

due to sequential addition of pig slurry and liquid poultry manure, and the loss of

organic matter. Again, the total N, P and K contents in composting DPS were

relatively low compared to mineral fertilizers (Table 1).

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3.2 Trace elements of paper de-inking sludge and its young compost. The trace

elements were present in low concentrations and showed low variability in raw DPS

(Table 2). Similar or higher values have been found in DPS from other paper sludges

(NCASI 1991; Bellamy et al. 1995; CQVB 1996). The low proportion of chemical

additives used during the manufacture of newspapers and printing, as the de-inking

plant uses about 80% old newspapers and 20% old magazines, could explain our

results.

Iron and Cu were the trace elements found in the highest concentrations in raw

DPS (Table 2). First, the presence of Fe is more likely linked to the addition of clay to

paper and the presence of ink in the waste. In general, kaolin is the clay used to coat

paper and contains 1% Fe2O3 (Murray 1984). Iron content in raw DPS is negligible

compared to the level found in soil that is less than 50 000 µg g-1 (Kabata-Pendias and

Pendias 1992). Secondly, when composting DPS, Fe content increased likely due to

sequential addition of pig slurry and liquid poultry manure, and the loss of organic

matter. Copper was measured in different chemical additives used in the paper de-

inking process, but was not present in large concentration. In addition, chipped wood

generally contains little copper (Tremblay and Beauchamp 1998). However, the

analysis of the inks of one local newspaper showed 10 685 µg g-1 of Cu in the cyan

(blue) ink (Beauchamp, unpublished results). Therefore, the Cu content of DPS is

likely related to the presence of cyan ink. In composting DPS, the loss of organic

matter resulted again in concentration of trace elements. Cu content varied between

84 and 118 µg g-1 during this study. In comparison, Cu content of DPS and its young

compost is lower than those of several sewage sludges (up to 17 000 µg g-1; Bellamy

et al. 1995), mineral fertilizers (up to 300 µg g-1; Kabata-Pendias and Pendias 1992) or

11

pesticides (up to 500 000 µg g-1; Kabata-Pendias and Pendias 1992). In this study, pig

slurry and poultry manure contained less than 5 µg g-1 Cu (detection limit) that could

only increase slightly Cu content of the young compost. Bellamy et al. (1995) reported

an average of 15 µg g-1 Cu in manure. Nevertheless, in the future, other carbon

sources low in Cu, such as peat, food residues, etc. should be evaluated in

combination with DPS and manure containing low amounts of Cu. According to the

compost regulation in Canada (BNQ 1997), a maximum of 100 µg g-1 Cu is allowed

for unrestricted use of compost (class ‘’A and AA’’) and 775 µg g-1 Cu for restricted

use (class ‘’B’’). Ninety-five percent of Quebec soils, under extensive agricultural use,

contain less than 36 µg g-1 of Cu (Giroux et al. 1992). Theoretically, adding 22 dry t

ha-1 year-1 of DPS or its young compost represents an addition of 2.4 to 2.6 kg Cu ha-

1 year-1. Under these conditions, the soil Cu content will have reached the limit of 63

µg g-1 for agricultural use, according to Canadian Environmental Quality Guidelines

(CCME 1999), after 25 to 27 years of annual applications of DPS or its young compost

to soil.

Zinc, manganese, chromium and mercury have been detected in raw and

composting DPS. Zinc, chromium and mercury contents were well below the

provided values for compost (Table 2). Zinc and Cr contents were similar or less than

the mean concentrations found in most soils (Kabata-Pendias and Pendias 1992).

Manganese content was similar to the one found in chipped wood (Tremblay and

Beauchamp 1998). There was no high concentration in heavy metals even though the

organic matter was decreasing. These trace elements should not bring changes into

soil. Arsenic, Cd, Co, Mo, Ni, Pb and Se were all below the detection limits in raw

DPS and its young compost.

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3.3 Organic compounds of paper de-inking sludge and its young compost.

Seventeen resin and fatty acids were analyzed in raw DPS and eleven were detected

(Table 3). The resin and fatty acids are natural constituents of wood but some fatty

acids, such as oleic, linoleic and palmitic acids, came more likely from the soaps used

for de-inking process. The total resin acids in DPS was about 2000 µg g-1, and using a

DPS density of 0.11 g mL-1, resin acid concentration can be estimated to be about 220

mg L-1, a level potentially toxic for aquatic life (Peng and Roberts 2000) but

apparently not toxic for compost microorganisms. In fact, most resin and fatty acids

decreased rapidly in composting DPS underlying their degradation by thermophilic

microorganisms (Yu and Mohn 1999) and possible leaching. In fact, only abietic acid

was detected after 24 weeks of composting and reflected the degradation of abietic-

type resin acids by compost microorganisms. It can be estimated that abietic acid

would be less than 3 µg g-1 when the compost would be mature, i.e., more than 24

weeks of composting. Currently, there is no regulations and relatively little attention

has been focused on the toxic effect of resin acids on terrestrial life, since trees, such

as conifers, that are rich in resin acids, undergo microorganisms decomposition in

forest litter. In addition, when raw DPS was amended to clay loam or silty clay loam,

microbial biomass increased (Chantigny et al. 1999), underlying non-toxic effect of

DPS and, by extrapolation, of resin acids. Raw DPS and its young compost should not

represent a threat to the terrestrial environment, but care should be taken to avoid

amending DPS to soil where resin acids could easily reach an aquatic system.

Nineteen polycyclic aromatic hydrocarbons were analyzed but only five were

detected in raw DPS (Table 4). Acenaptene, acenaphthylene, antracene,

13

benzo[a]anthracene, benzo[b+k]anthracene, benzo[a]pyrene, benzo[e]pyrene,

chrysene, dibenzo[ah]anthracene, dibenzo[ai]pyrene, 7,12-dimethyl-benzanthracene,

fluorene, indenol[1-2-3,cd]pyrene, 3-methylcholanthrene were all below the detection

limit (0.1 to 0.4 µg g-1). The total PAHs in raw DPS was less than 6 µg g-1 (including

detection limits). The present results were higher than those of rural and urban soils,

which showed median concentration of PAHs of 0.07 and 1.10 µg g-1, respectively,

but lower than road dust that can contain up to 137 µg g-1 of PAHs (Menzie et al.

1992). In addition, DPS presented lower PAHs concentrations than some Canadian

sewage sludges that were used in agriculture (trace to 100 µg g-1; Webber and

Goodin 1992). The five PAHs initially detected in composting DPS decreased over

time and none were detected after 24 weeks of composting, at a detection limit of 0.3

µg g-1. PAHs decreases could be due to microbial degradation, but also to

volatilization and photo-oxidation. According to the existing Canadian

Environmental Quality Guidelines (CCME, 1999), naphthalene should be less than 0.1

µg g-1 soil used for agricultural purposes. Theoretically and assuming no

degradation, adding 22 dry t ha-1 year-1 of DPS or its young compost represented

naphthalene addition of 6.6 g ha-1 year-1 (using the detection limit of 0.3 µg g-1).

Under these conditions and using naphthalene background of rural soil of 0.07 µg g-

1, the naphthalene soil content will have reached the Canadian Environmental

Quality limit after 10 years of annual applications of DPS or its young compost to soil.

Their environmental impact is probably less, since the extrapolation presented here is

linked to the detection limit, the soil naphthalene background and the absence of

degradation.

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Phenol compounds were analyzed and were generally under detection limits.

2-chlorophenol, O-creosol, M and P-cresol, 3-dichlorophenol, 2,6-dichlorophenol,

isoeugenol, 2-methoxy phenol (guaiacol), 2-methoxy-4-(2-propenyl) phenol (eugenol)

and phenol were all below 0.2 µg g-1. 2,3,5,6-tetrachlorephenol was below 0.3 µg g-1.

2-nitrophenol, 4-nitrophenol and 2-methyl-4,6-dinitrophenol were below 0.5 µg g-1.

4-chloro-3-methylphenol and 2,4-dinitrophenol were below 0.6 µg g-1. 2,4-

dichlorophenol and 2,4,6-trichlorophenol were below 1.0 µg g-1 whereas 2,4-

dimethylphenol was below 1.2 µg g-1. Pentachlorophenol was once found at 0.6 µg g-

1 but, on average, its content was below 0.3 µg g-1. Pentachlorophenol was not found

in American DPS (NCASI 1991). Contaminated paper lots could explain the random

presence of pentachlorophenol. However, the level of pentachlorophenol in paper

sludge should decrease over time since it is not in use in Canada anymore. The

phenols were generally absent of the DPS compost (data not shown). Once in a while,

m- and p-cresol were measured close to their detection limit. These two phenol

molecules do not contain chlorine and do not represent a threat to the environment at

the measured concentrations.

The content of halogenated hydrocarbons in raw DPS was low (Table 5). All

monoaromatic hydrocarbons showed values less than 0.1 µg g-1; only M+P-xylene

and O-xylene were detected (Table 5). In general, the volatile organic priority

pollutants, including halogenated and monoaromatic hydrocarbons, are low in pulp

and paper residues (NCASI 1991; CQVB 1996). Therefore, halogenated and

monoaromatic hydrocarbons should have a low impact on the environment and their

evolution in composting DPS was not followed.

15

Dioxin and furan contents in raw DPS were low. Within the dioxin family, only

octachlorodibenzodioxin was detected, at a concentration of 0.13 ng g-1 (± 0.05).

Values for tetra, penta, hexa and hepta-chlorodibenzo-dioxins and tetra, penta, octa,

hexa and hepta-chlorodibenzo furans were at their limit of detection (from 0.10 to

0.23 ng g-1 for dioxin family, and 0.12 to 0.49 ng g-1 for furan family). In the past,

important sources of dioxins were paper plants using the chlorination process and the

combustion of chlorinated materials. Today, penta-, hexa- and

heptachlorodibenzodioxins are associated with ink while octachlorodibenzodioxins

are mostly associated with old corrugated containers, surrounding ashes and

environmental contaminants accumulated by recycling paper (Shariff and Nguyen

1992). The presence of total equivalent for dioxin varied from 1 to 48 ng TEQ/kg in

Ontario (Bellamy et al. 1995) and from 2 to 14 ng TEQ/kg in Quebec (CQVB 1996). In

Quebec, the current guideline allows the unrestricted use of residual matter when

dioxins and furans are below 17 ng TEQ/kg (dw), and restricted use between 18 and

100 ng TEQ/kg (dw) (MEF 1997). DPS respected these criteria and the determination

of dioxins and furans in composting DPS was not followed in time. However, three

spot tests showed a total TEQ/kg of 3.5, 4.5 and 4.8 in one-year-old compost.

Polychlorinated biphenyls were not detected at a concentration higher than 0.2

µg g-1 in raw DPS. Arochlor 1242 shows a value 100 times less than the limit of 10 µg

g-1 permitted for sewage sludges used in agriculture (MENVIQ and MAPAQ 1991).

PCBs have been determined at concentration lower than 7 µg g-1 (NCASI 1991; CQVB

1996; Bellamy et al. 1995). For the last 30 years, PCBs have not been used in carbonless

paper (NCASI 1991). Our result showed that PCBs in DPS are below analytical

16

detection limits and should not be a diffuse source of PCBs. The evolution of PCBs in

composting DPS was not followed.

4. Conclusion

The contents in total C, N and other major mineral elements of raw DPS varied

over time. The contents in arsenic, boron, cadmium, cobalt, chromium, manganese,

mercury, molybdenum, nickel, lead, selenium and zinc were low, and showed low

variability. In raw DPS and its young compost, copper was the trace element that was

above the Canadian compost standard for unrestricted use of compost. Therefore,

when composting DPS, another source of organic matter containing low

concentrations of Cu should also be included. Otherwise, when Cu content of DPS or

its compost is above 100 µg g-1, this trace element should be followed until soil

content reaches 63 Cu µg g-1, the maximum allowed for soils used for agricultural

purposes according to Canadian Environmental Quality Guidelines.

In raw DPS, the fatty and resin acids, and polycyclic aromatic hydrocarbons

were the organic chemicals measured at the highest concentrations, limiting its use.

Since no regulations exist for resin acids and since it is a natural product, care should

be taken to avoid soil amendment where leachate can reach the aquatic system. For

PAHs, naphthalene should be followed until soil content reaches 0.1 µg g-1, the

maximum allowed for soils used for agricultural purposes according to Canadian

Environmental Quality Guidelines. In raw DPS, among the phenols, halogenated and

monoaromatic hydrocarbon, dioxin and furan, and polychlorinated biphenyl families,

most compounds were below the detection limits. After 24 weeks of composting,

most resin and fatty acids, and PAHs were not detectable, except for abietic acid, a

17

molecule present in high concentration in DPS, but also a by-product of abietic-type

resin acids decomposition by microorganisms. However, by the time the compost

would be mature, these molecules should have been degraded.

Composting is an avenue where the heterogeneity of the microbes involved

allows the degradation of most organic contaminants over time. The raw DPS and its

young compost, studied here, do not represent a major threat for the environment but

can require some follow up over time, especially for Cu and naphthalene soil content.

Composting DPS with animal manure appears an interesting avenue for an

integrated management of waste management, but more research is required in order

to obtain mature compost.

AKNOWLEDGEMENTS

The authors thank Daishowa, Inc. for supplying DPS, as well as for their financial

support. They are also thanking Les Composts du Quebec, Inc., for providing

composting platforms and technical support. We also thank Serge Yelle for his

criticisms during the collection data phase of this study.

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22

Table 1. Physical characteristics and nutrient elements of raw and composting DPS

over a period of 24 weeks.

Compound Raw DPSa Composting DPSb

0 week 8 weeks 16 weeks 24 weeks

pH 7.8 ± 1.6 7.7 ± 1.6 8.7 ± 0.1 8.1± 0.3 7.4 ± 1.7

Water content (%) 57 ± 2 59 ± 2 61 ± 2 70 ± 1 68 ± 1

Total C (%) 44.5 ± 3.0 43.9 ± 1.3 37.9 ± 0.8 36.5 ± 1.7 36.3 ± 4.1

Total N (µg g-1) 1475 ± 518 1595 ± 178 3266 ± 809 4220 ± 574 4667 ± 1127

C/N 294 ± 100 280 ± 27 162 ± 43 91 ± 8 81 ± 13

Total P (µg g-1) 100 ± 74 62 ± 13 940 ± 412 1353 ± 530 2300 ± 71

K (µg g-1) 154 ± 60 143 ± 17 1270 ± 231 2000 ± 115 2250 ± 460

Ca (µg g-1) 8313 ± 2299 7367 ± 1710 10567 ± 2995 15667 ± 4599 10050 ± 353

Mg (µg g-1) 623 ± 217 550 ± 35 807 ± 237 1050 ± 325 1050 ± 36

a Mean of 8 samples over a period of 2 years (± standard error of means)

b Mean of 3 compost piles (± standard error of means)

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Table 2. Trace element contents of raw and composting DPS over a period of 24

weeks and and Canadian compost standard

Trace element

Raw DPSa Composting DPSb Canadian Compost Standard

0 week 8 weeks 16 weeks 24 weeks Unrestricted use (class AA

and A)

Restricted use

(class B) --------------------------------------------- µg g-1 ------------------------------------------------ As <10 <10 <10 <10 <10 13 75

B <5 5.9 ± 1.4 6.5 ± 2.3 9.0 ± 6.1 <5 N.A. c N.A.

Cd <1 <1 <1 <1 <1 3 20

Co <2 <2 <2 <2 <2 34 150

Cr 4.7 ± 0.9 5.0 ± 0.9 4.8 ± 1.3 5.6 ± 2.4 6.3 ± 2.7 210 1060

Cu 111 ± 19 115 ± 50 84 ± 14 113 ± 14 118 ± 38 100 757

Fe 428 ± 167 420 ± 87 957 ± 230 1190 ± 130 1190 ± 223 N.A. N.A.

Hg 0.30 ± 0.30 0.05 ± 0.02 0.04 ± 0.01 <0.02 <0.02 0.8 5

Mn 20 ± 7 74 ± 87 54 ± 13 76 ± 13 79 ± 13 N.A. N.A.

Mo <2 <2 <2 <2 <2 5 20

Ni <10 <10 <10 <10 <10 62 180

Pb <20 <20 <20 <20 <20 150 500

Se <2 <10 <10 <10 <10 2 14

Zn 39 ± 22 25 ± 2 51 ± 15 71 ± 11 72 ± 12 500 1850

a Mean of 8 samples over a period of 2 years (± standard error of means)

b Mean of 3 compost piles (± standard error of means)

c N.A. : Not available

24

Table 3. Resin and fatty acid contents of raw and composting DPS over a period of 24 weeks.

Resin and fatty acid Raw DPSa Composting DPSb

0 week 8 weeks 16 weeks 24 weeks

-------------------------------µg g-1------------------------------

Abietic acid 863 ± 884 618 ± 313 24 ± 7 19 ± 11 10 ± 15

12-chlorodehydroabietic acid <30 <20 <3 <3 <3

14-chlorodehydroabietic acid <30 <20 <3 <3 <3

Dehydroabietic acid 288 ± 171 210 ± 70 23 ± 12 12 ± 11 <3

12,14-dichlorodehydroabietic acid <30 <20 <20 <3 <3

9,10 dichlorostearic acid <30 <20 <3 <3 <3

Isopimaric acid 102 ± 44 70 ± 18 18 ± 16 15 ± 17 <3

Linoleic acid 73 ± 55 36 ± 6 18 ± 19 <3 <3

Linolenic acid <30 <3 4 ± 2 <3 <3

Neoabietic acid 30 ± 18 16 ± 5 6 ± 3 <3 <3

Oleic acid 115 ± 51 70 ± 5 19 ± 20 <3 <3

Palmitic acid 197 ± 127 149 ± 29 90 ± 67 12 ± 11 <3

Palmitoleic acid <30 3 ± 1 15 ± 15 <3 <3

Palustic and levopimaric acids 126 ± 72 82 ± 29 49 ± 26 3 ± 2 <3

Pimaric acid 53 ± 27 34 ± 10 29 ± 33 <3 <3

Sandaracopimaric acid 43 ± 38 26 ± 8 9 ± 4 <3 <3

Stearic acid 254 ± 176 186 ± 31 98 ± 61 10 ± 10 <3

a Mean of 8 samples over a period of 2 years (± standard error of means)

b Mean of 3 compost piles (± standard error of means)

25

Table 4. Polycyclic aromatic hydrocarbon contents of de-inking sludge over a period

of 24 weeks

Polycyclic aromatic

hydrocarbon

Raw

DPSa

Composting DPSb

0 week 8 weeks 16 weeks 24 weeks

---------------------------------µg g-1---------------------------------

Benzo[ghi]perylene 0.2 ± 0.1 <0.2 <0.2 <0.3 <0.3

Fluoranthene 0.4 ± 0.3 <0.2 <0.2 <0.3 <0.3

Naphtalene 0.2 ± 0.1 0.2 ± 0.1 0.2 ± 0.2 <0.3 <0.3

Phenantrene 0.6 ± 1.0 0.3 ± 0.1 <0.2 <0.3 <0.3

Pyrene 0.7 ± 0.1 0.6 ± 0.1 0.4 ± 0.2 <0.3 <0.3

a Mean of 8 samples over a period of 2 years (± standard error of means)

b Mean of 3 compost piles (± standard error of means)

26

Table 5. Halogenated and monoaromatic hydrocarbon contents of raw DPS

Halogenated hydrocarbon Mean Halogenated and

monoaromatic hydrocarbon

Mean

-- µg g-1 -- -- µg g-1-- Bromomethane <1.0 Bromodichloromethane <0.3 Chloroethane <1.0 Bromoform <0.3 2-Chlorethyl vinyl ether <1.0 Chloroforme <0.3 Trichlorofluoromethane <0.5 Dibromochloromethane <0.3 Vinyl chloride <0.5 M+P-Xylene 0.06 ± 0.03 a Dibromoethane <0.4 O-Xylene 0.05 ± 0.03 a Carbon tetrachloride <0.3 Benzene <0.1 Chloromethane <0.3 Bromochloromethane <0.1 1,1-Dichloroethane <0.3 Chlorobenzene <0.1 1,2-Dichloroethane <0.3 Chloro-1,2-bromo-propane <0.1 1,1-Dichloroethylene <0.3 1,2-Dichlorobenzene <0.1 trans-1,2-Dichloroethylene <0.3 1,3-Dichlorobenzene <0.1 Dichloromethane <0.3 1,4-Dichlorobenzene <0.1 1,2-Dichloropropane <0.3 1,4-Dichlorobutane <0.1 cis-1,3-Dichloropropene <0.3 Ethylbenzene <0.1 trans-1,3-Dichloropropene <0.3 Mesistylene <0.1 1,1,2,2-Tetrachloroethane <0.3 A-Mesistylene <0.1 Tetrachloroethylene <0.3 Styrene <0.1 1,1,1-Trichloroethane <0.3 Toluene <0.1 1,1,2-Trichloroethane <0.3 Trichloroethylene <0.3

a Mean of 8 samples over a period of 2 years (± standard error of means)