Sludge from Pulp and Paper Mills
February 16, 2000
Dear Minister Sawicki:
Draft Three of the Pulp Mill Sludge Regulation and the Guideline for the Land Application of Pulp and Paper Mill Sludge will open the floodgates of land spreading of pulp mill sludge. We urge you to prohibit any further spreading of pulp mill sludge until testing has conclusively proven that it is safe for people in communities, workers and the environment.
Pulp mill waste water contains a mix of hundreds of chemicals that harm the environment. In British Columbia we know this only too well, and it took years to get laws that made the mills install secondary treatment to clean up the effluent. Secondary treatment removes those bad chemicals from the water and puts them into the sludge. Now the Ministry wants to approve spreading toxic sludge on the farms, forests and parks of British Columbia.
No one knows all of the contaminants in pulp mill sludge. We do know that it contains a variety of heavy metals, benzenes and phenolics. We also know that other jurisdictions in North America that have experimented with spreading sludge have experienced unexpected problems, and frequently halt the sludge spreading programmes in a wave of citizen protest.
In 1998, when your Ministry finally agreed to commit $20,000 to independent testing of the sludge to find out what is in it and whether it could harm people or the environment, the Council of Forest Industries withdrew from the advisory table. Behind closed doors, your staff continued to draw up regulations to allow the sludge to be spread across the province. The only testing ordered in the Regulation is for chemicals listed in the Contaminated Sites Act. This is inadequate. The few tests available show a wide range of poorly understood chemicals, including a large amount of material that cannot be identified.
If the regulation is passed, BC citizens will have no recourse, no avenue to appeal when truck after truck of sludge is dumped in their communities. Workers will be forced into contact with the sludge that often contains harmful bacteria.
Minister, we urge you to be guided by the Precautionary Principle in this matter and order thorough testing and consideration by independent scientists before you open the flood gates to over 50,000 truckloads per year of this unknown material spread all over British Columbia.
British Columbia has suffered enough toxic pollution from kraft pulp mills. Let's stop this contamination before it start
The BC Ministry of Environment Lands and Parks has issued Draft Three of a Sludge Regulation, which calls for some minimal testing of sludge before it is spread on farms, forests and parks. A further Ministry guideline on sludge handling and spreading warns that the sludge can contaminate ground water.
The pulp mills call it "bio solids." The government calls it pulp mill sludge. We call it Industrial Waste.
There has been no independent testing of this material to determine what's really in it. We do not know if this industrial waste causes genetic mutations or harms the hormone system of wildlife or people exposed to it. We do not know what gasses off the sludge to harm the workers who have to handle it.
What Is It?
Pulp mill sludge is a complex and changeable mixture of dozens or even hundreds of compounds, just like mill waste water. Some are well known, like heavy metals, dioxin and other organochlorines. Some, created by the bacteria in the treatment ponds, are probably unknown to science.
Environment Canada scientists in the Maritimes believe nonylphenol compounds are responsible for the decline in Atlantic salmon returns. We know that the pulp and paper industry uses one third of the nonylphenols in Canada, and we suspect these hormone disruptors wind up in sludge.
History of the Issue in BC
In 1994 a Kamloops farmer decided to experiment by feeding pulp mill sludge to cattle, until the Pulp, Paper and Woodworkers of Canada (PPWC) alerted the public. In 1996 a quiet rural neighbourhood near Krestova was upset when Celgar mill spread 80 tonnes of kraft sludge within 170 feet of a local well. The land was subsequently sold. In 1998 a neighbourhood near Quesnel BC was shocked to find Quesnel River sludge dumped on frozen land that sloped toward creeks and a local lake. The mill subsequently removed the sludge.
In 1996, the Ministry of Environment set up a Pulp Mill Sludge Advisory Committee that was to examine all aspects of pulp mill solid waste. Environmental groups like Reach for Unbleached! participated fully, repeatedly demanding that the waste material undergo testing before it was broadcast over the environment.
By 1998, when the Ministry of Environment agreed to do some independent testing, to see what really was in the sludge, the Council of Forest Industries (COFI) promptly withdrew from the committee, and the budget for testing was lost.
The Ministry produced the Draft Three Sludge Regulations and Guidelines in October 1999.
There has been some limited spreading of pulp and paper sludge in British Columbia under special approvals. Paper mill sludge is mixed with GVRD municipal sludge and spread on Scott Paper poplar plantations on islands in the Fraser River. Quesnel River Pulp spreads some of its sludge on farmland in the Quesnel area. Celgar kraft sludge has been spread on some orchards and agricultural land.
This regulation throws the doors wide open for over 50,000 truckloads of sludge per year to be spread in BC communities, with virtually no government oversight and no independent monitoring.
The Pulp, Paper and Woodworkers of Canada has called for sludge to be treated as regulated "toxic waste" until "the pulp and paper industry can supply verifiable and irrefutable proof (through valid scientific testing) that there are no ill side effects to the workers who handle these products"
The US Environmental Protection Agency (EPA) is considering listing paper mill sludge as hazardous waste.
Ontarians have been complaining about the spreading of pulp and paper sludge for years. In 1999 the Ontario Environmental Commissioner wrote: "The applicants cite concerns about the contamination of soil, ground water and surface water, as well as impacts on livestock, wildlife and soil microorganisms. Many have also complained about odour, and symptoms such as headaches, burning eyes and breathing difficulties associated with freshly spread sludges."
The State of New Hampshire abruptly cancelled a mill sludge spreading program in 1998 after the discovery of unexpected toxic chemicals leaching into ground water. Additionally the state is now facing a lawsuit over the spreading of mill sludge that should have been classified as hazardous waste.
In Ontario a multi million dollar lawsuit has just been settled over the death of 43 acres of grapes where paper sludge had been piled in between the rows at Hernder Winery in St. Catherines.
What We Want
* Peter Ronald, Campaign Coordinator, Georgia Strait Alliance;
* Delores Broten, former Executive Director, Reach for Unbleached, Box 39, Whaletown, British Columbia Canada V0P 1Z0
Maureen Reilly is an environmental researcher with Uxbridge Conservation Association, Ontario. She would like to hear from organizations or individuals who have experience or information about this issue.
There appears to be growing literature on the health impacts of bioaerosols in both indoor and outdoor environments. From the experience of affected individuals from Beaverton, Cornwall, and Sault Ste Marie, there appears to be growing evidence that some individuals are becoming impacted by bioaerosols from paper mill sludge. This is a health concern since properties adjacent to large land application projects are often subjected to unincorporated sludge operations as often as twice a year. Unincorporated refers to the practice of top dressing, or leaving the sludge on the surface of the soil without mixing it into the soil. Often sludge piles are left to decompose for months or even years, and when these piles are opened there is often powerful impacts such as burning of nostrils, and breathing difficulty. Thus there are a wide variety of conditions under which sludge decomposes and can have a variety of on site and off site effects.
The sludges appear to support a wide variety of microbial growths, and further work should be done to characterize the types of growths that are present in the sludge in various stages of decomposition. Bioaerosols are also a concern in the composting of sewage sludges.
Reported effects including tightening of the chest and allergic reactions. There is some concern about mutagenicity, and acute toxicity as well. Much of the literature on bioaerosols reviews the heath impact on healthy male employees at composting sites. It does not capture the impact of these bioaerosols on subject populations living adjacent to sludge operations. These individuals may be elderly, immunocompromised from transplants, cardiac surgery, diabetes, or may be children or infants in poor health. These individuals are subject to the bioaerosols on a 24 hour a day, seven day a week basis. Unlike an affected worker, they have no recourse to remedies available to workers such as changing jobs or duties, nor are they eligible for Workmans Compensation for injuries they have suffered.
For these reasons, the Ministry of the Environment and the Ministry of Health should require land applied sludges to be thoroughly investigated for bioaerosols, including, mould and fungal growth, mycotoxins and endotoxins, under a wide variety of environmental conditions. There are health standards for the presence of such growths in the environmental health and safety field, and this literature can be used as a starting point for investigating the levels of such agents present in rural land application initiatives, especially in those areas where health impacts are suspected.
Here is a small sample of the available literature:
Abstract: OSHLINE 0903-1936 Thorn et al 1999. Airway inflammation among workers in paper industry.European Rep.J. 13 (5) 1151-1157
00212944 Epstein & Epstein 1985. Health Risks of Composting. BioCycle 26(4) 38-40
00212942 Occurrence of Aspergillus fumigatus during Composting. Applied Environmental Microbiology. 34(6) 765-772
00192869 Rylander 1987. Role of Endotoxins. European J. Of Respiratory Disease 71 supl 154 p136-144
00164040. Clark 1986. Comparisons of Organic Dust Exposures. Am.J.Ind.Med. 10(3) 286-287.
00146810 Clark 1986. Health Effects Associated with Wastewater Treatment. J. Water Poll. Control Fed. 56(6)
00077057 Millner et al. 1980. Dispersal of Aspergillus Fumigatus from Sewage Sludge Compost Applied & Env. Microbiology 39(5) 1000-10009
Darragh A. et al. 1997. Quantification of Air Contaminants at a Municipal Sewage Sludge Composting Facility. Appl. Occup.Environ.Hyg. 12(3)190-194
Rylander R. 1994. Organic Dusts from knowledge to prevention. Scandinavian Journal of Work and Environmental Health 1994;20 special issue: 116-22
Olenchock S. 1994. Health Effects of Biological Agents: The Role of Endotoxins. Applied Occupational Environmental Hygiene 9(1), January 1994 62-64
Macher J.1999. Bioaerosols: Assessment & Control. Chptrs. 19,23.24.
ACGIH, Cincinnati, OH, 1999,
Pulmonary Responses After Wood Chip Mulch Exposure, Wintermeyer et al, American College of Occupational and Environmental Medicine, Division of Pulmonary and Critical Care Medicine, University of California San Francisco.
The following document was presented to the British Columbia Provincial Advisory Committee on Pulp Mill Solid Waste Disposal as the beginning of discussions about testing the safety and benefits of landspreading sludge.
How to Proceed
Industry needs (or wants) to dispose of this material into the general environment, either air or land. Therefore, industry should pay for testing to determine the suitability of such disposal, as part of the cost of doing business. The public should not have to pay for the disposal of potential hazards into the commons.
Industry should set up a fund, which will be held by government. The contributors must be determined by industry, baring in mind that the entire North American industry will benefit if we are able to resolve this issue to the satisfaction of all parties.
Disbursement of the fund would be under the control of a nine-member tripartite committee, with representation from several scientific disciplines, especially including microbiology, chemistry, toxicology and biology - three people from each sector ?one nominated by the sector with no veto, one nominated by the sector but subject to veto, and three members, one for each sector, chosen by consensus of the whole.
The fund would pay for the following research.
Testing and Monitoring Required
From an analysis of available data on the chemical composition of sludge, ash and green liquor residues from pulp and paper mills, (see What We Know About Sludge) the most obvious observation is the limited nature of these data, in terms of the range of chemicals tested, the frequency with which residues are analysed, and the amount of variability in the chemical composition of different sludge samples.
Clearly, to adequately assess the environmental affects associated with the land application of pulp mill sludge and ash residues, stringent guidelines need to be established regarding monitoring of a suite of chemicals of concern in the residues themselves, and the concentrations of these contaminants in amended soils and groundwater in trial plots. Along with comprehensive chemical analysis, sludge needs to be assessed for potential environmental impact by using a number of ecologically-sound biomonitoring programs. Further, there is no short or long term benefit to society to allowing the dispersal of these wastes unless a definitive environmental gain can be demonstrated. In other words, there must be a demonstration of benefit, not merely an indication of absence of harm, in order for society to approve the long term risk.
Monitoring sludge composition and environmental impacts of land application
Priority pollutants and chemicals of concern that must be analysed in pulp mill residues include heavy metals, PCDD/PCDFs, chlorinated hydrocarbons, chlorobenzenes, PAHs, chlorinated phenols, chlorinated catechols, chlorinated guaiacols, phthalates, resin acids, alkylphenols and alkyphenol ethoxylates, and plant sterols.
Standardization of methodology for the analysis of specific chemical components needs to be a priority, and mills should be required to release the results of these analyses to interest groups in the public.
One of the major problems with a biomediated solid like sludge, especially a chemically complicated one, is that we do not know what compounds have been created by the bacteria in the system, and therefore we do not know what to look for, nor what its impacts will be. However, rather than ignoring this problem, there must be scientific ways to approach the issue, begin testing, and come to resolution. Ignoring the question will not solve any of our problems.
If results indicate the possibility of proceeding, the next step in chemical analysis would have to be development of protocols to characterize variability. The ability to predict batches of sludge which fall beyond the regular range of constituents would allow any testing program to proceed with greater confidence.
Prior to any land application of solid residues, the levels of chemicals of concern need to be routinely demonstrated to fall below realistic regulatory levels. Small-scale sludge mulch trials need to be undertaken so that the long-term affects of sludge application on the chemical composition of soil and ground-waters can be monitored over a two to five year time-frame. These preliminary studies should also incorporate a comprehensive biomonitoring program to assess the impact of sludge amendment on local soil microbe populations and a range of sentinel animal and plant species. These studies also need to assess the impact of various levels of composting - from eight hours to a year - and assess the hazards to workers of various ways of working with this material during the composting process. The implications of handling massive amounts of material which give off hazardous substances, and whether safe methods can be designed, must be assessed, especially by the workers involved.
Toxicity tests conducted in laboratories under arbitrarily defined conditions are incapable of perfectly simulating environmental conditions. In the actual waste, there may be unidentified components. In the actual environment many other factors may have an influence, therefore there is a need to complement laboratory data with data collected under field conditions. The use of multiple species in toxicity testing is important to simulate the effects of waste and leachates on soil micro and macro fauna.
Even with biomonitoring, the variability of each batch of sludge will necessitate continual testing:
Long term testing will be required to determine the real impact of sludge on soil, because at this point the studies claiming beneficial results have been short-term.
Compounds of concern possibly present in primary and secondary kraft sludge
Chemicals for which a series of characterization tests must be conducted, and, if present, for which soil microfauna toxicity, sorption, mobility and degradation pathways must be traced before the issue of sludge land spreading can be considered, and which must also be considered in the issue of burning of sludge and dispersal of airborne contaminants.
NOTE: many of these chemicals have both a chlorinated and non-chlorinated
Alkylphenols and alkyphenol ethoxylates d:
Chlorinated acetic acids (mono, di, and tri) and acetones
Chlorobenzenes (di, tri, tetra, penta, and hexachlorobenzene):
Chlorinated catechols, guaiacols and phenols:
Dioxins and Furans
MX [3-chloro-4(dichloromethyl)-5-hydroy-2(5H) - furanone]:
Terpenes, chlorinated and nonchlorinated mono, di and triterpenes:
Nonchlorinated organic compounds (Toluene, napthalene, dibutyl pthalate, xylene, acids and vanillins identified in effluent)
* Prepared by Delores Broten, with the help of Dr. Colleen O'Mallee and Paul
August 11, 1997
The BC Ministry of Environment has released its decision on the appeal of the Powell River kraft pulp mill's permit to spread grate ash and lime dregs in "experimental" applications. The appeal, by writer Anne Cameron, Paddy Goggins, and Reach for Unbleached, was denied in its attempt to have the permit squashed, but substantively upheld in the matter of further testing as requested by Reach and ordered by Deputy Director of Waste Management Dave F. Brown, the official hearing the appeal.
The mill wished to use the grate ash as a roadbed material, and apply the lime dregs to a disused golf course as a soil amendment.
The decision grouped the grounds for appeal and responded to each argument.
A) The permit fails to protect the environment:
Ruling: "For the most part" dismissed:
B) The permit violates the precautionary principle
Ruling: UPHELD! Permit must be amended to require:
C) The waste material contains phthalates, including DEHP
Ruling: Denied; but additional testing to determine if the DEHP was a "transitory contaminant."
D) lack of public consultation
Copies of all required reports to be provided to appellants and the community
March 15, 1997
Prepared For: Reach for Unbleached! Box 39 Whaletown, British
Columbia Canada V0P 1Z0
The following report summarizes our assessment of the land application of Powell River pulp mill grate ash, primary and secondary sludge, and lime dregs. Clearly, land application of these industrial by-products is a desirable alternative to land filling. Forests that are being harvested for pulp or wood products are being robbed of carbon and nutrients that would otherwise be recycled into the system. Thus, land spreading of these by-products represents an attempt to recover some of the carbon loss from the forest floor and mineral soil. Numerous considerations, however, must be taken into account when considering the use of any one of these by products. Heavy metals, dioxins, organic halogens, nutrient loading, habitat alteration, and succession influence are some of the concerns associated with landspreading of these materials. In this report we attempt to address the following:
Assessment Of Chemical Analyses
The physical and chemical characteristics of pulp mill by-products of the Powell River Division (PRD) mill of MacMillan Bloedel in Powell River, BC are provided in a report prepared by Organix (1995). These data were generated to fulfill requirements of a permit application to the BC Ministry of Environment, Lands, and Parks which would allow for the land application of grate ash from power boilers, composted primary sludge, secondary sludge effluent, and green liquor dregs. This report describes the intention to divert these by-products from the land fill to be used as follows:
High concentrations of dioxin in the primary and secondary sludge has precluded broad scale land application of these by-products. The permit application has thus been scaled back to treatment of roads with grate ash and pilot treatment of an abandoned golf course with sludge. Regardless of permitting, the following addresses the chemical characteristics of each of the by-products should they be land applied in the future.
Physical And Chemical Analyses And Their Implications
Grate Ash and Green Liquor Dregs
The grate ash has a moisture content of close to 50% and a dry bulk density of 0.35 to 0.44. Upon drying, the material should create a crust on the road surface. Although it would likely not be vulnerable to wind dispersal, truck traffic will clearly destroy the aggregate and, thus, enhance potential for wind dispersal. Rain impact on the uncovered surface would also likely result in raindrop dispersal of the material and ultimate surface runoff.
The material has a pH of 7.5 to 10.5 representing liming potential. The material is N limited (C:N =100:1), but the quality of the carbon present (percent hydrolyzable sugars, amino acids, and polyphenolics) is not given to indicate whether the C present would result in increased microbial immobilization of soil N.
Plant available nutrient levels are given in Table 2 of the report. It must be kept in mind that plant available levels of metals would be highly suppressed by the alkaline conditions associated with the ash (Lindsay, 1979). This is also reflected in Table 2 which presents the total nutrient concentrations. Sodium levels are relatively high, but are balanced by the very high calcium concentrations. Sodium adsorption ratios (SAR = [Na]/(([Ca]+[Mg])/2)1/2) of the plant available nutrients is close to 10, a level considered to disperse clay aggregates and potentially reduce infiltration rates (Schwab et al., 1996). Boron concentrations present in the sludge are high enough to warrant some concern. Boron toxicity to crop species has been reported at concentrations as low as 0.33 ppm (Schwab et al., 1996).
Nitrate and ammonium are surprisingly high considering high C:N, this implies that inorganic N will either be rapidly immobilized or the C present in the ash is highly recalcitrant thus not resulting in N immobilization. Sulfate is high, and in the later two samples, Al and phosphate are quite high. The high pH and high Ca concentration should reduce any potential Al hazard, but will also potentially limit P availability in the long run. Under these conditions Al will exist in hydroxide complexes or precipitates and P will precipitate as insoluble Ca-phosphates. The concentrations of nutrients in the ash are similar to those reported by Naylor and Schmidt (1989). Their work indicates a net increase in productivity of alfalfa with ash amendment to an acid, high Al soil. It should be noted, however, that alfalfa requires moderately acid to slightly alkaline conditions for growth and N fixation. Roadside grasses that are adapted to somewhat acid soils may not respond as well to such ash amendments. Clearly, the Powell River grate ash will provide some fertility but will create N and micronutrient limited conditions.
The proposed pilot trial for application of the green liquor dregs appears appropriate, as long as thorough testing of the treated soils is performed. They are low in N and would not serve well as a soil amendment because of N limitations. This material is also very high in Na and relatively low in extractable Ca creating a significant Na hazard for soil. These high Na concentrations may cause dispersion of soil organic matter and clay particles leading to reduced infiltration and ponding of water on the soil surface. If ponding occurs, the large quantities of sulfate present in the sludge may be reduced to sulfide, a form not available for plant use. It should be noted, however, that sulfate reducing bacteria have the capacity to degrade aromatic organic compounds under anaerobic conditions (Paul and Clark, 1996).
Dioxin and Other Organic Contaminants
Although the Powell River report suggests that runoff and leaching are the most probable route of off-site movement of the dioxins, there is significant potential for wind dispersal as well. The potential for air dispersal of dioxins is greatest with the use of the grate ash as a dust suppressant. In this case, trucks driving over the treated roadbed would destroy the aggregate releasing the low density, pulverized material for wind dispersal. Inhalation and dermal absorption of dioxin is an alternative pathway for exposure (Banks and Birnbaum, 1991; Nessel et al., 1992). If later tests show a higher dioxin concentration or if numerous road applications results in a concentration of dioxin in a limited area, then the road treatment with this by-product should be reconsidered.
There are numerous other organic compounds of potential concern that might exist in the ash that have not been monitored for in the ash including: total organochlorines, adsorbed organic halides (AOX), chlorolignins, total phenolics, total phthalate esters, PCBs, and several specific organochlorines. A more thorough discussion of these missing analyses is given in a later section. Analysis of AOX has come under significant scrutiny due to the uncertainty of the analyses and questions surrounding the use of the results (McCubbin and Folke, 1995; Sullivan and Douek, 1996). Currently there are no maximum contaminant levels given for any organic compounds in ash intended for land application under EPA guidelines outside of dioxin.
The low metal and dioxin content of the grate ash makes this by-product a likely candidate for land application. This material has significant liming potential and could definitely be used in reclamation of disturbed acidic soils. We foresee only limited concern with the application of the grate ash to road sides or beneath an asphalt seal. Use of the ash as a dust suppressant needs to be carefully monitored for off site movement of the product. A pilot program should be conducted with replicated plots and thorough monitoring of off-site movement of the ash as runoff or dust. Further suggestions for monitoring are given below.
Primary and Secondary Sludge
Currently the primary and secondary sludge are to be used only in a pilot trial on an abandoned golf course. The following discusses some of the chemical and physical questions that need to be considered during such a trial.
The moisture content of this material indicates that hauling costs may be relatively high. Ammonium levels are high considering the high C:N ratio associated with this material. Ammonium will likely be readily immobilized upon application of this material to soil. Base cations in this material, Ca, Na, Mg, and K are again relatively high, but the numbers presented are highly variable. Sodium concentrations are not high enough to create soil dispersal problems. Aluminum concentrations are quite high and pose a potential problem with Al toxicity at the pH associated with this material. Sulfur, Cu, and Zn are all present in limited supply, but these concentrations should not pose any plant nutrition problems.
The secondary sludge is a far superior fertility amendment compared to the primary sludge. This material has a C:N of about 10:1, low bulk density, high B, Ca, Na, and Mg concentrations, and low available Al concentration. Although Al does not appear to be a concern in the secondary sludge, the SAR for this material is well above Na hazard ratings for irrigation water (Schwab et al., 1996). Although not likely a problem with turf or forest applications, the B concentrations present have the potential to be phytotoxic to crop species under acidic conditions. The land application of the secondary sludge, may result in the dispersion of soil aggregates and the long term loss of soil permeability.
Dioxin and Other Organic Contaminants
Since dioxin is highly adsorbed to soil particles, it is thought that ingestion of soil is required to allow for exposure. However, disturbance of soils treated with dioxin containing materials may result in dust dispersal. Dermal and inhalation exposure to the chlorinated phenols are possible alternative routes of exposure. Dermal absorption appears to very slow (Banks and Birnbaum, 1991). Inhalation or ingestion of airborne dust particles might be a more likely route through which humans and other animals might be exposed to dioxin from land that has been treated with dioxin (Olson et al., 1988). Thus, dust dispersal should be added as a potential off site loss of dioxin that should be monitored along with runoff. Leaching of dioxin is actually of limited concern because of the strong sorption of dioxin to soil colloidal material.
Microbial degradation of dioxin in soil is considered to be extremely slow (half life of 3 - 10 years in subsoils). Since dioxin in soil does not affect soil respiration rates, it is thought that the reason for slow degradation rates is a result of the strong surface sorption of dioxin to soil organic matter. Dioxin is very hydrophobic and thus is strongly sorbed to soil organic matter. Composting of sludge should only increase the degree of sorption and reduce the rate of degradation. The long-term fate of these compounds is unknown. Any condition that stimulates C mineralization (e.g. application of N fertilizers or lack of C input to soil following disturbance such as tillage or logging with whole tree harvest) may result in the release of dioxin.
Again numerous other possible organic contaminants likely exist in the sludges (Table 1). The relatively high concentrations of TCDD in the sludge indicates that there would likely be high concentrations of total organochlorines (TOC). It would be useful to know what concentrations the various compounds exist at in the sludge prior to any land application of such material. In this case, we would consider the classes of compounds shown in Table 1. Since there is little toxicity data available with regard to these compounds, risk assessments for these compounds are not readily available. However, the potential exists for synergistic effects of combinations of different chlorinated organic contaminants. Ideally, these should be screened for more than just lethal dose curves or cancer risk as various compounds may pose a number of "minor" or long-term health effects that do not pose an immediate health effect. However, this is unlikely because of costs and the shear numbers of possible impacts that would have to be addressed.
Chlorinated phenols are present in a number of forms in primary or secondary sludge at the Celgar mill. Since levels of dioxin are far higher at Powell River compared to Celgar, it is likely that levels of other chlorinated organics will also be in higher concentrations in the Powell River sludge. Kookana and Rogers (1995) provide an excellent discussion of the possible fate of chlorinated organic compounds once land applied. Chlorinated phenols may be bioaccumulated in soil macrofauna (e.g. earthworms with 1800 ppm of CPs in soils with only 54 ppm of CPs). Such bioaccumulation will clearly be biomagnified in higher trophic levels (e.g. song birds and raptors). Toxicity levels for soil macrofauna are greatly influenced by pH, PCP is approximately three times more toxic to a species of earthworm at pH 7.0 than at pH 4.0. Thus, application of grate ash with the sludge would likely increase toxicity of chlorinated phenols to soil macrofauna. Earthworms are favoured by alkaline conditions, thus the very conditions that would favour their presence, would result in greater toxicity in the presence of chlorinated phenols. Soil microorganisms in general appear to be more tolerant of chlorinated phenols. It is not uncommon for soil respiration rates and eve total biomass to increase immediately following pesticide or CP applications (Mooreman, 1994; Sherman, 1996). This increase in respiration is actually due to application of a C source and short term kill of some organisms creating a new food source (Mooreman, 1994). This process may result in an increase in total microbial biomass, but generally results in a reduction in diversity of soil organisms.
Table 1. Concentration of organic compounds commonly found in pulp mill effluent following bleaching with hypochlorite (adapted from Kookana and Rogers, 1995).
Chlorinated phenols are also known to exhibit phytotoxic effects on numerous food plants (Kookana and Rogers, 1995). These compounds are thus highly stable in soils and degrade very slowly. These compounds may be methylated, sorbed (surface adherence), or bound to humic materials in soil. In this process, the organic halides are actually polymerized into the humus molecule, making them impossible to identify or extract using solvent extractions (Mooreman, 1994; Bollag and Lu, 1990). Composting of sludge will increase levels of humic acids and will likely increase the sorption and formation of bound residues of chlorinated phenols. These compounds will likely remain in this form until some disturbance causes significant mineralization of soil organic matter as described above. The released organic halides may be more or less toxic than the form that was applied to the soil. There is very little information regarding this process as humus degrades so slowly.
Halogenated alkanes and alkenes (e.g. trichloroethylene, trichloroethane, chloroform) are common in untreated effluent. TCE is known to be carcinogenic and mutagenic. Toxicity to soil organisms is poorly understood. Degradation of these compounds is thought to be greatly cometabolic (enzymatic degradation by organisms degrading other compounds) and thus dependent upon a readily available source of C (which the sludge should provide). Analysis of TCE, TCA and chloroform should be performed on the sludge to determine its concentration. These should then be monitored over time in soil.
Chlorolignins are a major component of pulp mill effluent originating from the bleach process. These are partially degraded chlorinated lignin fractions. These tend to have a low aromatic component and a high carbonyl and carboxyl content and are about 10 percent Cl by weight. This is really the major component of the AOX fraction. There is little known with regard to toxicity to soil organisms or higher organisms. The large size and complexity of these compounds generally reduces their toxicity (difficult to take across membranes). However, conditions that stimulate degradation of lignin compounds (low available C content) result in increased toxicity effects. These compounds are not readily degraded by microorganisms, but the compounds released are considered to be potentially more toxic than the long chained compounds. Degradation of AOX by actinomycetes has been reported to be relatively rapid under some conditions (Winter et al., 1991).
Clearly a standardized method of AOX determination must be used for comparison of AOX from different mills and following land application. Sorption on activated carbon, shaking methods, and ultrafiltration are all used (Sullivan and Douek, 1996). These authors suggest the use of the shaker method for high molecular weight AOX and the ultrafiltration method for low molecular weight AOX.
Use of bleach substitutes or even a partial bleach substitution greatly reduce the concentrations of TOCs in the mill effluent. A 100 % chlorine substitution at the first bleach stage has been reported to result in a AOX concentration reduction from 5.2 to 0.6 kg t-1 (Kookana and Rogers, 1995). Secondary treatment of the sludge, generally results in a significant reduction (20 - 50%) in AOX.
Nonchlorinated organic compounds exist in relatively high concentrations in primary and secondary pulp mill sludge. Groups of compounds and specific compounds of concern include resin acids, vanillin, xylene, naphthalene, and dibutyl phthalate (Kookana and Rogers, 1995). All o these compounds are found on the EPA priority pollutant list, although none are considered to be mutagenic or genotoxic. Vanillins and resin acids are known to be significant toxins of aquatic life. It is likely that these compounds exist in relatively high concentrations in the Powell River sludge.
Potential Long And Short Term Impacts Of Land Application Of Pulp Mill Sludge
The benefits to land application of pulp mill sludge are many and have been demonstrated in numerous studies (Brockway and Urie. 1983; Schimek et al., 1988; McDonald et al., 1993; Bellamy et al., 1995; Sherman, 1995). Increased tree growth, increased crop nutrition, and improved soil physical conditions can be readily attributed to pulp mill sludge applications. Obviously, pulp mill sludge is somewhat limited by the high C:N ratio in primary sludge. Mixes or composts of primary and secondary sludge to create a C:N of 20:1 create a high quality soil amendment. This material provides the soil with a slow release of minerals, a source of replenishment of base cations, and a source of C for microorganisms in soils that may be starved for C following years of cultivation or forest rotations. The increased C content should stimulate microbial activity and result in an increased humus content which relates directly to increased water holding capacity, increased CEC, increased metal sorption, and increased aggregation of soils. Lastly an important benefit of this type of application is diversion of a useable organic material from the waste stream into a beneficial use.
Applications of 2 - 24 tons/ha have demonstrated significant increases in crop yields and productivity similar or greater than that accomplished with synthetic fertilizers (Simpson et al., 1983; Shimek et al., 1988). Application levels of less than 10 t ha-1 appear to be needed to achieve significant yield increases with minimal loss of NO3- to ground water (Brockway and Urie, 1983). This is going to be dependent upon the C:N of the sludge in question. Nitrogen loss rates would have to be determined based on expected crop uptake and estimated N mineralization rates based on C:N.
Applications of ash or lime dregs are useful as liming agents and increasing base cation status of the soils. Both materials create a highly efficient lime source which can be used to adjust the pH of acid soils for agricultural purposes. Base cation deficiencies can also be corrected using these materials (Naylor and Schmidt, 1989). Beneficial application rates of ash to a hay crop were reported to be a minimum of 12 Mg ha-1. Yield increases in forest ecosystems treated with these materials have been modest at best (McDonald et al., 1994).
Unfortunately, there are a number of real and potential long-term detriments associated with the application of pulp mill sludge to forest plantations or even road right of ways (Kraske and Fernandez, 1993; McDonald et al., 1994). Since much of these impacts are described above, the following only focuses on the inorganic chemical and plant community impacts.
Leaching of NO3- would likely be a potential concern on the sites treated with Powell River secondary sludge, but not on sites treated with primary sludge. The high levels of Na in Powell River sludge may create a long term problem with dispersion of soils and actually decreased free drainage (due to dispersion of clays and loss of macropores).
Enhancement of weed communities with sludge applications has been reported. Salal growth in a red spruce forest was reported to be luxuriant in the high N application of pulp mill sludge plus fish wastes (McDonald et al., 1994). In this same study production of top growth with limited or no diameter growth in established forest communities was reported. Although numerous sludges contain elevated levels of heavy metals, Powell River sludge does not pose a major metal contamination threat. Obviously, land spreading of sludge can create significant dioxin contamination of soils and poisoning of wildlife (Olson et al., 1988). As described above, the various compounds present in the sludge can have an adverse impact on soil micro, meso, and macro fauna diversity, although total numbers will likely increase with the sludge application. Annual applications of sludge will result in the accumulation of various contaminants which may result in decline in soil organisms or development of phytotoxicity.
In a general sense, the application of sludge to roadsides, poplar plantations, and forest soils must be studied under controlled conditions. The potential phytotoxicity of high Al concentrations must be followed. Calcium will leach more readily under the conditions in this climate than Al. Sites receiving high levels of sludge may ultimately have elevated, potentially phytotoxic concentrations of Al. The fate of numerous organic compounds associated with the sludge can be ascertained as well. Compounds of immediate concern appear to be the dioxin, various chlorinated phenolics described above, and phthalate esters. The controversy surrounding AOX, the relatively low toxicity of the high molecular weight AOX, and its unreliability as an assay reduce its utility as an index of system contamination following application of sludge.
Sampling Protocol For Future Monitoring Of Effects
Although the Powell River pulp mill sludge appears to be of value as a fertilizer (secondary sludge) and as a soil amendment (primary sludge) with little metal concerns, the concentrations of dioxin in these sludges indicates that there is likely high concentrations of various organic compounds. Based on the description of the use of the pulp mill by-products from Powell River, it is clear that a more elaborate study design must be used to determine the effects of the applications on their intended purpose (e.g. poplar growth) as well as on environmental contamination and environmental biotic indicators. This type of intensive study would be of great utility to the mill and would be of interest to those living in surrounding areas. Due to unclear health concerns regarding the land spreading of primary and secondary sludge, grate ash, or green liquor dregs, no large scale applications of these materials should be made until small scale research studies involving intensive monitoring for dioxin and other chlorinated organic compounds of concern in plant tissues, soils, and animal life. Pilot studies using replicated plots including untreated control plots should be used to determine actual treatment. These plots should be set out in a randomized complete block design to avoid effects of fallout gradients (e.g. industrial fallout contamination of control plots should they be placed closer to the source).
Sampling of soils should be done on a monthly basis for the first year and then on an annual basis from that time forward. Borrow pits should be instrumented with sediment traps to determine amounts of runoff and sedimentation of the borrow pit. If possible, a means of monitoring dust loss (especially from treated road sites) should be set up. Something as simple as fly paper mounted on poles near the site or as elaborate as air pollution monitoring devices could be used. Earthworms or other soil macrofauna could be collected and analysed for bioaccumulation of dioxin. Soils, dust, and sediment should be analysed for metals and compounds of concern noted above. Plant tissue should be monitored for signs of phytotoxicity and analysed for Cr and Al concentrations. If water courses are nearby, fish and lower aquatic organisms should be monitored during summer months for measurable levels of contaminants (pre and post sampling).
Additionally, a more elaborate analysis of the sludge, grate ash and liquor dregs must be performed. The concentration of all of the contaminants in the sludge from metals to dioxin will vary with time and with location. Since the halogenated organic compounds are directly related to the bleaching process, the concentrations of these compounds would potentially be greatest in effluent directly released from first bleaching stages. Additionally, dioxin and furan concentrations appear to be increased during aerobic secondary treatment of sludge, thus timing of sampling the secondary sludge would potentially greatly influence concentration of these compounds. At the same time, however, TOC and AOX have been reported to decrease by over 50% during secondary aerobic treatment of the effluent.
The quality of sludge from different plants also varies greatly. A plant using a 50% chlorine dioxide substitution will have approximately 50% less total AOX compared to a conventional chlorine bleach plant. At the same time, these plants may have a greater COD than the conventional bleach plants. Many US mills that use a partial ClO2 bleach substitution claim TCDD levels to be below detection limits in primary sludge. We know that 100% ClO2 substitution at the first bleach stage results in a reduction of TCDD and TCDF to below detection limits and AOX levels to be decreased by nearly 10 fold. Use of extensive delignification and oxygen prebleaching can reduce the amounts of required bleach at the primary bleach stage and alternative approaches to lignin degradation during the pulp stage has been reported to allow for effective use of peroxide bleach.
Compounds of concern that should be focussed on in future studies are: total chlorophenols, specific mono, di, and tri chlorochatecols, chloroguaiacols, chlorovanillin, chlorogaiacol, and PCP. Halogenated alkynes and alkenes including TCE, TCA, and chloroform. All dioxin and furan compounds should be monitored closely. Finally, resin acids and phthalate esters should be monitored in this pilot study.
Banks, Y. B. and L. S. Birnbaum. 1991. Adsorption of 2,3,7,8, tetrachlorodibenzo-p-dioxin (TCDD) after low dose dermal exposure. Toxicol. Appl. Pharm. 107:302 310.
Bellamy, K. L., C. Chong, and R. A. Cline. 1995. Paper sludge utilization in agriculture and container nursery culture. J. Environ. Qual. 24:1074-1082.
Bjerke, D. L., T. J. Brown, N. J. MacLusky, R. B. Hocberg, and R. E. Peterson. 1994. Partial demasculinization and feminization of sex behavior in male rats by in utero and lactational exposure to 2,3,7,8,-tetrachlorodibenzo-p dioxin is not associated with alterations in estrogen receptor binding or volumes of sexually differentiated brain nuclei. Toxicol Appl. Pharm. 127:258-267.
Bockheim, J. G. T. C. Benzel, R. Lu, and D. A. Thiel. 1988. Groundwater and soil inorganic leachate nitrogen in a Wisconsin red pine plantation amended with paper industry sludge. J. Environ. Qual. 17:729-734.
Bollag J. M. and S. Y. Liu. 1990. Biological transformation process of pesticides. pp. 169-211. In: Pesticides in soil environments. Cheng, H. H. (ed). SSSA Book Series #2. American Society of Agronomy, Madison, WI.
Brockway, D. G. and D. R. Urie. 1983. Determining fertilizer rates for forests from nitrate-N leachate and groundwater. J. Envrion. Qual. 12:487-492.
Dickerson, R., L. H. Keller, and S. Safe. 1995. Alkyl polychlorinated dibenzofurans and related compounds as antiestrogens in the female rate uterus: Structure-activity studies. Tox. Appl. Pharm. 135:287-298.
Kookana, R. S. and S. L. Rogers. Effects of pulp mill effluent disposal on soil. Rev. Environ. Contam. Toxicol. 142:14-65.
Kraske, C. R. and I. J. Fernandez. 1993. Biogeochemical responses of a forested watershed to both clearcut harvesting and paper mill sludge application. J. Environ. Qual. 22:776-786.
Leita, L., and M. DeNobili. 1991. Water soluble fractions of heavy metals during composting of municipal solid waste. J. Environ. Qual. 20:73-78.
Lindsay, W. 1979. Chemical Equilibria in Soils. Wiley, NY.
McConnell, E. E., G. W. Lucier, R. C. Rumbaugh, P. W. Albro, D. J. Harvan, J. R. Haas, and M. W. Harris. 1984. Dioxin in soil: Bioavailability after ingestion by rats and guinea pigs. Science 223:1077-1079.
McCubbin, N. and J. Folke. 1995. Significance of AOX vs. unchlorinated organics. Pulp Paper Can. 96:43-48.
Mooreman, T. B. 1994. Pesticide degradation by soil microorganisms: Environmental, ecological, and management effects. Pp. 121-165. In: Soil Biology: Effects on soil quality. Advances in Soil Science. J. L. Hatfield and B. A. Stewart (eds.). Lewis Publishers, Ann Arbor, MI.
Naylor, L. M. and E. Schmidt. 1989. Paper mill wood ash as a fertilizer and liming material: field trials. 72:199-206.
O'Connor, B. I. 1996. Characterization of pulp and paper mill solid residues: a review. Misc. Rept. 324. Pulp Paper Res. Inst. Canada. 13 pp.
Olson, L. J., H. A. Anderson, and V. Beth Jones. 1988. Landspeading dioxin contaminated paper mill sludge: a complex problem. Arch. Environ. Health 43:186 189.
Sulivan, J. and M. Douek. 1996. Method and sample relate problems in the determination of AOX in effluents. 79:145-154.
Pritchel, J. R. W. A. Dick, and P. Sutton. 1994. Comparison of amendments and management practices for long-term reclamation of abandoned mine lands. J. Environ. Qual. 23:766-772.
Schwab, G. O., D. D. Fangmeier, and W. J. Elliot. 1996. Soil and water management systems. John Wiley, NY. 371 pp.
Sherman, W. R. 1995. A review of the Maine Appendix A sludge research program. TAPPI 78:135-150.
Simpson, G. G., L. D. King, B. L. Carlile, and P. S. Blickensderfer. 1983. Paper mill sludges, coal fly ash, and surplus lime mud as soil amendments in crop production. TAPPI 66:71-74.
Simeoni, L. A., K. A. Barbarick, and B. R. Sabey. 1984. Effect of small scale composting of sewage sludge on heavy metal availability to plants. J. Environ. Qual. 13:264-268.
Thiel, D. A., S. G. Martin, J. W. Duncan, and W. R. Lance. 1989. The effects of sludge containing dioxin on wildlife in pine plantations. TAPPI 72:95-99
Vasconcelos, E. and F. Cabral. 1993. Use and environmental implications of pulp-mill sludge as an organic fertilizer. Environ. Pollution. 80:159-162.
Vera, C. J. and Servello, F. A. 1994. Effects of paper mill sludge in spruce fir forests on wildlife in Maine. J. Wildl. Mange. 58:719-727.
Winter, B., A. Fiechter, and W. Zimmermann. 1991. Degradation of organochlorine compounds in spent sulfite bleach plant effluents by actinomycetes. Appl. Environ. Microbiol. 57:2858-2863.
Statement of Intent
How much pulp and paper mill sludge is there?
In Canada, mills installed secondary treatment after the passage of the AOX and Dioxin emission laws in the early 1990s. Interior mills do not have as much problem with sludge, because they use large lagoons for treatment. Coastal mills which installed UNOX systems expected to burn the sludge, but this material is difficult to handle, hard to dry, causes increases in sulphur dioxide emissions, and gasses off toxic hydrogen sulphide compounds.
In Canada in 1994, estimates were that 1222 t/d of primary sludges were produced, while the amount of secondary sludge was expected to increase tenfold to 282 t/d in the five years from 1990 to 1995. MB Powell River produces about 25,000 dry tons per year of primary sludge and 7500 tons of secondary sludge. [At a wild guess, this is about 2,200 gravel truckloads.]
What do we do with it now?
What's the problem?
Using sludge or composted sludge residues as a soil amendment in forests or on agricultural land is gaining popularity as a means of disposal of these solid residues. Obviously there are benefits in adding sludge rich in organic material to soils. However, the extensive chemical processing involved in converting wood fibre to pulp means that residues such as sludge and fly-ash are potentially contaminated with a number of chemicals, some of which (including organochlorines generated in bleached Kraft processing) are known to persist in the environment and are toxic, carcinogenic, or affect reproduction in a range of animals (including humans).
Currently there are no guidelines regulating the chemical composition of sludge residues. This document is an attempt to review what is known about sludge and to highlight the gaps in the existing data.
Chemical composition of sludge
"The severe cadmium restrictions obstruct the use of sludges and ashes for soil improvement, landscaping, and as fertilizer". Helsinki University, Department of Forest Technology Research: "Treatability of pulp and paper industry solid wastes"
Maximum acceptable levels
The study examined the long-term effects of biosolid (mixed domestic/industrial anaerobically digested sewage sludge) application to forested land on the kidney cadmium concentrations in omniverous mice and insectiverous shrews in Western Washington. Various amounts of biosolids were applied over a 15 year period. Cadmium levels in shrews in treatment sites (apart from the lowest dose sites) were significantly greater than controls. 'Cadmium accumulates in tissues of herbiverous and omniverous rodents inhabiting areas amended with biosolids or sewage wastewater, but the concentrations are generally not high enough to cause toxicity.'
Nickleson, S.A. and West, S.D. (1996) Renal cadmium concentrations in mice and shrews collected from forest lands treated with biosolids. J. Environmental Quality Vol.25:86-91
Other Heavy Metals
"...There is evidence that in some parts of Europe that large scale regional problems are partly due to heavy metal deposition in some compartments of the environment, particularly raw humus in forest soils, lakes and arable soils." (p. 23)7.
Trace nutrients such as chromium, cobalt, copper, molybdenum and zinc, all essential to plants are toxic at relatively low concentrations. Arsenic, cadmium, lead, mercury, nickel and selenium play no vital role in metabolic functions, and are toxic to plants at low concentrations.8
Dioxins in Sludge
The US EPA has estimated that at current exposure levels, the dioxin related cancer risk is between 1 in 1,000 and 1 in 10,000; that is 100 to 1000 times higher than the generally 'acceptable' risk levels for cancer causing agents.9 The principal sources of dioxin in the environment are chemical manufacturing, waste incineration, metal refining and smelting, pulp and paper mills, and 'reservoir' sources (dioxin-contaminated soils and sediments).10
"The presence of trace organic components in pulp and paper solid residues, either as contaminants or by-products of the particular process, has been an area for concern for regulatory agencies and the general public. A primary concern in the land application of pulp and paper mill residues has been the presence of trace amounts of chlorinated dioxins and furans".4
"The environmental risk from using secondary sludge on poplar stands comes from the presence of PCDD/Fs. ...The main pathways of exposure include the accumulation of PCDD/Fs, nutrient leaching and runoff."2
n = number of sludge samples
The variability in dioxin levels in different sludge samples from the same mill is not easily explained, but given the up to 28-fold concentration difference in dioxins detected in secondary sludge samples it is clear that monitoring of sludge composition should involve multiple testing of different 'batches', and not rely on one off sampling of a 'generic' sludge.
"Due to the limited data available it is difficult to generalize as to whether the dioxin content of all pulp and paper sludge and ash is acceptable for land application. However given that the concentration of dioxins in most sludge samples is extremely low and the fact that the industry has taken steps to vastly decrease its discharge of dioxins, would seem to imply that dioxin contamination should not be of great concern."4
"...the variability shown by this limited sampling indicates that highly contaminated solids occur frequently enough to be of serious concern and that more sampling would be required to realistically estimate loadings or the risk entailed in land application. It must be remembered that merely 'diluting' a highly contaminated waste with a larger amount of lesser-contaminated material just avoids the problem instead of reducing overall contaminant loadings. While dilution may serve to decrease bulk concentrations of solids below some regulatory benchmark, the total environment loadings (the most important aspect of persistent and bioaccumulative contaminants) still increase."13
"...[Following composting of the sludge] PCDD/F [polychlorinated dibenzo p-dioxins and polychlorinated dibenzofurans] concentrations will be the same or slightly above those in the primary sludge because they resist biological breakdown."2
"The secondary sludge currently contains PCDD/Fs at higher concentrations than would be found in soils."2 "A typical first year application would be about 12 tonnes/ha dry matter. Based on current data this would add approximately 1.8 pg/g PCDD/F TEQ to the soil."2
"Monitoring data collected in sludge-amended forest soils in Wisconsin indicate TCDD levels in eggs of some bird species, particularly robins, that are sufficiently high to suggest risks to developing embryos. ...'Best estimate' risks as a result of runoff into aquatic areas adjacent to treated areas suggest that exposures may pose low to moderate risks to fish and to predators eating such aquatic life"15
Experimental evidence shows that after weathering in soil for a year 50 70% of the original concentration of dioxin is recoverable.12 The persistence of dioxins that leach out of sediments and soil residues into wetland areas or rivers is also high, with the half-life of 2,3,7,8-TCDD in a model aquatic environment calculated to be in the order of 600 days.12
The complex nature of bleached pulp mill effluent in relation to their organochlorine content, has resulted in the monitoring of discharges by means of the collective parameter AOX which represents the absorbable organic halogens (organic compounds containing bromine, chlorine or iodine; generally it is chlorine that is measured) present in water or sediment/soil samples.
AOX has serious limitations as aregulatory parameter because of the undefined nature of the components that make up an AOX result. Similarity in AOX concentration in samples does not necessarily indicate similarity in AOX composition30. In BC, pulp and paper mill effluents show large fluctuations in AOX levels (up to 30%), even when samples are taken within hours of each other.13 AOX levels have been shown to be significantly decreased in ECF mills (down to 0.2 kg/tonne) and secondary treatment of effluent can further reduce AOX by half .18
While a large number of the organochlorine molecules discharged by the pulp and paper industry are derived from reactions between lignin or cellulose components of the pulp and bleaching chemicals, the specific structure, properties and toxicity of many of these chlorinated compounds are unknown.17 Although it was previously thought that high molecular weight chlorolignin, which makes up 70-80% of total AOX discharged by pulp and paper mills,30 was non-bioaccumulative, non-toxic and inert, there is now some evidence to contradict this.19 Chlorolignin itself appears to be resistant to microbial degradation,19 but other organochlorines in pulp residues (such as chlorinated phenolics), can be microbially converted to more lipophilic compounds in treatment ponds, yielding compounds that have bioconcentration factors 10-100 times greater than the parent compound.20
In soil AOX can range from 210 to 1440 ug/g (210 ppm to 1440 ppm) which is probably the upper natural range (e.g. humic soil from bogs).24 There are no regulatory standards for AOX in soils or for residues applied to soils in Canada.
Other Organic Compounds of Concern
Some of the chlorinated compounds included in this category may also figure as part of the collective AOX measurements noted above, however the chemical properties of cholorphenolics and chloroform are such that they form part of the Extractable Organic Halogen (EOX) fraction. Since chlorophenols are relatively lipophilic in nature they have the potential to bioaccumulate in the fatty tissue of organisms and therefore cause toxic effects.30 There is evidence linking chlorophenols with health effects in humans including depression, anemia, liver and kidney dysfunction and death in acute occupational exposure.30 Laboratory studies indicate that chlorophenols may have carcinogenic and mutagenic properties, and may interfere with reproduction in some animals.30
Non-chlorinated phenolic compounds ( phenol, cresols, acetovanillin, acetosyringone and hydroxybenzaldehyde) were detected in shallow soil waters underlying a poplar plantation which had been mulched with pulp mill sludge. Monitoring the soil and ground waters at this site over a three year showed non-chlorinated phenolic compounds at concentrations of 5 500 ppb.14
Other organic compounds in this group are highly volatile (eg chloroform and toluene) and are essentially undetectable in sludge after treatment processes (but are likely redeposited some distance from the source, possibly in a modified form). As with the majority of sludge contaminants, there is little (if any) data available regarding the biological fate of these chemicals and their degradation products.
Phthalates are chemicals that are used as plasticisers in the manufacture of plastics and in some inks used to print on plastics. They are fat soluble and so have the ability to accumulate in body fat.25 Di-(2 ethylhexyl)phthalate (DEHP, also called di-sec-octylphthalate) makes up one quarter of total plasticisers ever produced25, and is known to leach from food wrapping and plastic tubing.12 Phthalates are considered to be the most abundant man-made pollutants, with human dietary intake estimated to be in the range of tens of milligrams per day (Danish EPA). DEHP is a testicular toxicant and has been associated with reduced sperm counts and increased incidence of miscarriage in occupationally exposed workers.25 Other phthalates have been shown to have estrogenic properties (ie act as hormone disruptors) in laboratory studies.25
Phthalate contamination has been recorded in sediments of Lake Superior (DEHP: 200 ppb), and municipal sludge samples from seven different sites in the Netherlands showed an average DEHP concentration of 72.2 ppm.12 High concentrations of DEHP have been noted in fish in the Gulf of St Lawerence (6.5 ppm in mackeral).12
In assessing the fertilizer value of pulp mill sludge, aside from justified concerns about contaminant levels of heavy metals, organochlorines and other organic chemicals, it is important to consider the concentrations of essential plant nutrients as well as those metals or salts likely to be toxic to plants at elevated concentrations.
"Other important characteristics [of residues applied to agricultural land] are carbon to nitrogen (C/N) ratio as well as boron and salt concentrations... It is known that excess concentrations of boron can lead to phytotoxicity and lower crop yields while excess salts can lead to soil deterioration and reduced water availability."4
Currently only a handful of studies have monitored the effects of sludge application on plant growth and on the chemical composition of soil and groundwater potentially affected by sludge leachates. Data from one study suggests that two years after land application there was neither a soil risk nor a significant improvement in trials using a mixture of pulp mill sludge and cattle slurry.31
"The C:N ratio of 30:1 in combined sludge is optimum for plant growth. The limiting macro- and micronutrients for plant growth appear to be phosphorous and copper."1
Salt concentrations in sludge
"The salt content of sludges can also be a constraint to use on some crops. Salt concentrations are high for some sludges (up to 1.5%) which can injure salt-sensitive plants....and may also lower the pH of the soil. The salt content of sludge then, is a concern, but not enough use has occurred to determine the extent of the problem. Field research may be needed...." Usable Waste Products for the Farm, an Inventory for Maine, 1986
"The [sludge] residual is slightly saline with a higher proportion of sodium than ideal, but this is not a great concern."1
The salt concentrations of sludge (involving lithium, sulphate, calcium, magnesium and sodium) are significant with respect to their impacts on soil properties and subsurface water qualities.8
"Water quality in soil under the [pulp mill sludge] mulch is significantly and rapidly affected by the application. Within one or two months of application, total dissolved contents nearly double. ...Concentrations of the various species [Cl, NH3, Ca, Fe, K, Mg, Mn, Na, Sr] begin to decrease in the second year after application."14
In sludge-treated plots sodium, potassium and chloride concentrations were elevated in surface water compared to levels in control plots.14
"Based on past experience and the literature, ground water and vegetation testing [in sludge-applied land] does not appear warranted."2
The annual maximum sodium addition to Ontario soils is 400-1000 kg/ha. In Ontario the Sodium Adsorption Ratio (SAR) should be less than 5."6
"The coarse texture and high carbon content of the fly ash does not lend itself as a stand-alone soil medium, although it could be used as a soil amendment."1
a = Di-(2-ethylhexyl)phthalate b = Dibutylphthalate c = Phenanthrene
"The concentration of tin and boron in the grate ash marginally exceeded the BCE criteria for Agriculture."2
"The only element of concern could be boron which was slightly higher than the CMCS criteria for agricultural soils."1
Green liquor dregs
From an analysis of available data on the chemical composition of sludge, ash and green liquor residues from pulp and paper mills the most obvious observation is the limited nature of these data, in terms of the range of chemicals tested , the frequency with which residues are analysed, and the amount of variability in the chemical composition of different sludge samples. The current regulations governing the monitoring of the chemical composition of solid wastes from pulp mills are totally inadequate.
"Since the land application of pulp and paper solid residues is handled on a case-by-case basis in Canada, the provincial agencies are generally hesitant in providing a 'one size fits all' outline of analytical work that might be required for residue characterization. This is especially true in the case of organic contaminant characterization (e.g., dioxins, PAH, chlorinated organics, etc.).This information would only come to light during specific negotiations between the mill and the relevant authorities."6
In granting permission for the land application of sludge from Quesnel River Pulp Company, BC Ministry of Environment, Lands and Parks required the testing of sludge for a range of heavy metals, phosphorous, nitrogen and sodium. In order to monitor the environmental effects of sludge application the ministry requires annual analysis of soil samples for conductivity, Sodium Adsorption Ratio (SAR), nitrogen, phosphorous, sulphate and total carbon concentrations. Groundwater in the vicinity of the sludge is required to be tested annually for nitrates, sodium and hardness.33
"Regulatory agencies may be more willing to grant permit approvals if it can be demonstrated that a [sludge] residue's chemical composition varies within a given range which would consistently be in compliance with the guidelines. Unfortunately this type of information appears to be lacking from the general literature."4
"Land application of organic residuals such as combined [pulp mill sludge] residual is currently viewed by regulators as a discharge of 'industrial waste' to the environment."1 No regulations have been drafted for the land application of 'industrial' by-products.1
Clearly, to adequately assess the environmental affects associated with the land application of pulp mill sludge and ash residues stringent guidelines need to be established regarding monitoring of a suite of chemicals of concern in the residues themselves, and the concentrations of these contaminants in amended soils and groundwater in trial plots. Along with comprehensive chemical analysis, sludge needs to be assessed for potential environmental impact by using a number of ecologically sound biomonitoring programs.
Monitoring sludge composition and environmental impacts of land
Standardization of methodology for the analysis of specific chemical components needs to be a priority, and mills should be required to release the results of these analyses to interest groups in the public.
Prior to any land application of solid residues, the levels of chemicals of concern need to be routinely demonstrated to fall below realistic regulatory levels. Small-scale sludge mulch trials need to be undertaken so that the long-term affects of sludge application on the chemical composition of soil and ground-waters can be monitored over a two to five year time-frame. These preliminary studies should also incorporate a comprehensive biomonitoring program to assess the impact of sludge amendment on local soil microbe populations and a range of sentinel animal and plant species.
Toxicity tests conducted in laboratories under arbitrarily defined conditions are incapable of perfectly simulating environmental conditions. In the actual environment many other factors may have an influence, therefore there is a need to complement laboratory data with data collected under field conditions.32
The use of multiple species in toxicity testing is important to simulate the effects of wastewaters and leachates on aquatic food-chains.32
"One major advantage of biological toxicity tests, over chemical analysis, is their direct assessment of potential biotic impact without extrapolation from chemical analysis of uncertain completeness of substances analysed."32
One or two years after pulp mill sludge application to a forested area in Maine there was no evidence that sludge affected breeding birds or small mammal populations in the area. However, caution was recommended against extending these results to other species or forest communities. "In particular, forest communities with abundant earthworm populations differ in their potential for TCDD bioaccumulation and transfer to vertebrate wildlife ... 'Because direct effects of TCDD are species specific, we suggest that future research should emphasize field toxicological studies to determine concentrations of TCDD and related compounds and routes of exposure for potential high-risk species. Longer-term studies may be needed with longer-lived species because TCDD bioaccumulates in food chains.'34
Even with biomonitoring, the variability of each batch of sludge necessitates continual testing: "Because of the variable nature of paper sludge from different mills, it is recommended that each product should be subject to investigation before being recycled to agricultural land."35
Long term testing will be required to determine the real impact of sludge on soil, because at this point the studies claiming beneficial results have been short-term: ...'It is recognized that much of the work completed to date in the Niagara region has been short-term, and that tong-term effects of repeated annual sludge treatments, at the same locations are needed to document sludge effects on soil properties and soil performance.'36
1) Beneficial Reuse Pilot Trials - Landing Revegetation and Landscape Soil Production, PGL Organix for Celgar Pulp Company, January 1996, and further testing supplied by Jim McLaren, Technical Services, Celgar Pulp
2) Documentation to support an Application for a Permit under the Provisions of the Waste Management Act (Refuse) Macmillan Bloedel Limited - Powell River Division in Powell River BC, PGL Organix, November 1995 and further testing supplied by Drew Kilbeck, Environmental Manager
7) Heavy Metals Emissions Substantiation Report, Background Information Paper for a Heavy Metals Protocol under the United Nations Economic Commission for Europe Convention on Long Range Transboundary Air Pollution, prepared for Environment Canada by C. C. Doiron & Associates, February 1996
8) Agricultural utilization of paper mill sludge in the Niagara area. Bellamy, K.L. et al. (1990) Environment Canada 13th international Symposium on Watewater Treatment and Drinking Water 2nd Workshop, Montreal, Nov.14-16: pp65-81
10) Health assessment document for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds. US EPA (1994) Vol I, Office of Research and Development, EPA/600/BP-92/001a, External Review Draft, June 1994.
16 and references therein) Towards zero-effluent pulp and paper production: the pivotal role of totally chlorine free bleaching. Johnston, P.A. et al.(1996) Technical report 7/96, Greenpeace Research Laboratories, Exeter, UK
17) Modelling the fate of 2,4,6-trichlorophenol in pulp and paper mill effluent in Lake Saimaa, Finland. Mackay, D. et al. (1996) pp 219-228 in: Environmental fate and effects of pulp and paper mill effluents. Servos, M. et al. St. Lucie Press, Florida.
18) Origins of effluent chemicals and toxicity: recent research and future directions. Servos, M. (1996) pp 159-168 in: Environmental fate and effects of pulp and paper mill effluents. Servos, M. et al. St. Lucie Press, Florida.
19) Environmental fate and distribution of substances. Carlberg, G. E. (1996) pp 169-178 in: Environmental fate and effects of pulp and paper mill effluents. Servos, M. et al. St. Lucie Press, Florida.
20 and references therein) Recent advances in environmental fate of chemicals from pulp mills. Gifford, J. S. (1996) pp 271-280 in: Environmental fate and effects of pulp and paper mill effluents. Servos, M. et al. St. Lucie Press, Florida.
23) Effects of internal process changes and external treatment on effluent chemistry. Stromberg, L. et al. (1996) pp 3-18 in: Environmental fate and effects of pulp and paper mill effluents. Servos, M. et al. St. Lucie Press, Florida.
30 and references therein) AOX as a regulatory parameter: A scientific review of AOX toxicity and environmental fate. McKinnon, L. (1992) Draft report prepared for BC Ministry of Environmnet, Lands and Parks, September 11, 1992
32) Toxicity of TCF and ECF pulp bleaching effluents assessed by biological toxicity tests. Ahtiainen, J et al. (1996) pp 33-40 in: Environmental fate and effects of pulp and paper mill effluents. Servos, M. et al. St. Lucie Press, Florida.
33) Permit (PE 13412) issued by BC Ministry
of Environment, Lands and Parks to Quesnel River Pulp Company for
the discharge of sludge to the ground. June 14, 1995
Miscellaneous Report MR 324
NOTE: The points made in this critique apply with even greater relevance to the individual mill waste characterizations which accompany various permit applications in the province of BC.
In Paprican Miscellaneous Report MR 324 - Characterization of Pulp & Paper Mill Solid Residues: a Review, (B. J. O'Connor, February 1996) the author sets out to review literature pertaining to the industry's solid waste, focusing on characterization of the wastes, comparisons to municipal and sewage sludges, and comments on the variability of the available data. This is done to " facilitate the selection of the most appropriate uses for the solid residues."
The use being considered here is land application of the solids. The mill wastes contain nutrients which could be used as fertilizer, but are also laced with contaminants. (The review confines itself only to Dioxins and Heavy Metals.) The reasoning is that if a typical mill waste can be defined ,and contaminant levels are no worse than the guidelines used for municipal sludges, then the case for land application is made stronger. In this evaluation of the review, we take exception to some of the author's methodology, comparisons and conclusions, based on the data provided.
The author states that "the properties of the residues vary considerably between pulp and paper processes". It is this variability which should be of concern in both characterization and uses of these wastes. From the data shown in the Appendices, variability is the predominant characteristic of the residues.
It is useful to examine the data and references in the Appendices before any conclusions or graphs are drawn , or averages (means) calculated. It is the author's use of graphs and means that are the most problematic aspects of data interpretation in this review since they give the impression of a legitimacy which is not reflected in the data from which they are supposedly derived.
Looking at Appendix 1 for Heavy Metals, it is clear that the number of sludges and ashes sampled is low in relation to the range they exhibit. Typically, n = about four or five samples, from a low of one to a high of ten. The ranges are often over several orders of magnitude.
This raises the question of the legitimacy of the calculated mean. When attempting to characterize a material known to have widely varying characteristics, it is not enough to merely calculate a mean and assume that it is representative of the whole. Just one data point can have a profound effect on the average. If the data points range widely, as they often do in this review, it would not be correct to give much weight to the calculated mean generated by such low numbers of samples.
The range data here would indicate that the calculated means are a mathematical construct rather than a reasonable approximation of a typical waste. The known variability of mill waste composition, which is reflected in the range data, plus the low number of samples would indicate that there is not enough information here to reach an intelligent conclusion about what constitutes a typical waste.
Despite these warning signs, the author calculates the means, then compounds the problem by bar-graphing the results for comparison with various guidelines.
Unfortunately, we are not supplied with the individual sample concentration data, which would have been useful in evaluating the adequacy of the mean calculation, but we can still draw some conclusions from the range and sample number data. It can be seen in one case that at least one out of five samples had Cadmium results close to or over the limit the author uses as a benchmark. Another case has one out of six ash samples over the limit, with lesser but significant ranges for the other sample groups. Graphing the mean of these groups tends to obscure this information. If the author concludes from the bar- graphs that most samples were of low concentration, he should also conclude that a significant number were not.
Calculating the average "smooths out" the differences between a relatively small number of samples, and tends to lose information by obscuring variability. Small sample groups contain less information than large ones, so every effort should be made to maximize the information available. The conclusion this should lead to is that for both sludges and ashes we should be cautious about relying on few and infrequent analyses to characterize these solid wastes.
When the data for Dioxins is examined, we find that the bar-graph has been generated by only six sludge and three ash samples. While the results are not averaged this time, the variability of the few samples is again the most obvious characteristic of the data set.
The limited data presented show that one out of six sludges (17%) and one out of three ashes (33%) are very close to his benchmark limit. Again, the variability shown by this limited sampling indicates that highly contaminated solids occur frequently enough to be of serious concern and that more sampling would be required to realistically estimate loadings or the risk entailed in land application. The review deals with this by noting that "it is difficult to generalize as to whether the dioxin content of all pulp & paper sludge and ash is acceptable for land application."
Nonetheless, he does, saying that "the concentrations of dioxins in most samples were extremely low"and that "dioxin contamination should not be of great concern". It must be remembered that merely "diluting" a highly contaminated waste with a larger amount of lesser-contaminated material just avoids the problem instead of reducing overall contaminant loadings. While dilution may serve to decease bulk concentrations of solids below some regulatory benchmark, the total environmental loadings (the most important aspect of persistent and bioaccumulative contaminants) still increase.
Several points made in the section on Dioxins should be addressed:
It is the author's last point on variability which should receive more prominence, as it becomes the controlling factor from which all other decisions should come, including interpretation of analytical results. Most importantly , it affects our ability to realistically characterize the residues and has a profound effect on our ability to judge the risks involved in land application.
Only three papers are cited as research on the variability of the residues chemical composition, focusing on nutrients and some metals. There are no references to dioxin levels or other persistent organochlorines. This information "appears to be lacking in the general literature".
However, the scant information on variability is instructive. Confining itself to nutrients and metals, these studies show changes over time of 10-20 fold, 3-70 fold and "up to 50- fold."
It has been shown earlier that a significant number of the samples were close to or over the limits for even the relatively forgiving comparisons to municipal and sewage sludges. Factoring in these variabilities would predict a high probability that a significant number of residues would be highly contaminated.
It is not surprising to find great variability in the wastes of a mill when all of the variables which change, daily and hourly, in the mill operation are considered. It is to be expected that characterization of the waste streams of a complex operation will not be simple. Experience has shown that conclusions reached on the basis of inappropriate use of the average may be not only inaccurate, but wildly inaccurate. It is therefore important not to apply simplistic techniques of data reduction to this task.
It is also important to understand when there is not enough information to reach an intelligent conclusion regarding environmental samples. That perspective seems to be lacking in this review. While circumstances sometimes force decisions based on questionable data, that is not the case here. The characterization data necessary to resolve the questions can be obtained through more sampling, analysis, and research. In this we concur with the author.
What kinds of analysis do we need for solid wastes?
It may be that a dual approach is best. On one hand, a proper search of the available analytical data which does exist would reveal which compounds we already know exist, or are likely to exist, in the effluents. On the other word, priority pollutants, or chemicals of concern, should be defined and applied to whatever we find when we search the lit.
First, some things we know we should be looking for are:
This is by no means a complete list, and would be added to as additional information comes to light, hopefully from a greater effort in comprehensive testing of the waste streams to monitor the waste's composition. This detailed characterization will not only aid in adjusting mill operating procedures, but will also be a first step in evaluation of synergistic effects.
Further to the testing parameters, the frequency of sampling needs to be increased, until the issue of variability is settled, either by testing of each batch to be land-spread, or by eventual predictability of results due to correlation with operating conditions at the mill in question.