Toolkit for Identification and Quantification of Releases of Dioxins, Furans and Other Unintentional POPs
PART II Emission Factors
Source Group 9 Disposal / Landfill
Non-thermal waste disposal processes are addressed in this source group. Except in certain cases, these processes are only routes of PCDD/PCDF release, not sources of PCDD/PCDF formation and release. PCDD/PCDF that are already present in the wastes being treated become concentrated or released to one or more vectors by these treatment and disposal processes (see Table II.9.1).
These processes are used to dispose of PCDD/PCDF-contaminated wastes, many of which are residues of processes that have been addressed in other source groups. The management of these residues, e.g. physical, biological, chemical, or thermal treatment or containment in secure landfills, burial in dumps and pits, spreading on land, or direct discharge of untreated effluents into rivers, lakes or oceans, can result in PCDD/PCDF releases to the environment.
The fate of PCDD/PCDF-containing residues should be well-documented, because of the potential for mismanagement to result in increased and widespread exposure in humans and domestic animals. As an example, the Belgian chicken incident originated in a small volume of used PCB oil (contaminated with PCDF) being introduced into fat subsequently used for producing feedstuff for domestic animals (EU SCAN 2000).
Table II.9.1. Overview of source categories included in group 9 - Disposal
8 - Miscellaneous Potential release route Source categories Air Water Land Product Residue a Landfills, Waste Dumps and Landfill Mining x X b Sewage / sewage treatment (x) x x x x c Open water dumping x X* d Composting x x e Waste oil treatment (non-thermal) x x x x x
* Sediment in creeks, rivers, estuaries and oceans.
With relevance to the provisions of Article 5, sources in this category can be classified as follows:
Table II.9.2. Relevance to Article 5, Annex C of the Stockholm Convention
No Toolkit source category Part II Part III Relevant source category in Annex C 9e Waste oil treatment (non-thermal) X Waste oil refineries
An example of elaborating a source inventory and release estimate for this source group is included in the example inventory 10.
Landfills and waste dumps are sites where waste is buried in engineered landfills and unlined pits or deposited in surface piles (open dumps). An engineered landfill is a constructed waste storage site where the wastes are contained and controlled by liners and caps. In contrast, pits, dumps and piles have no engineered containment or pollution control techniques and are largely unregulated and uncontrolled.
In landfills and dumps, biodegradable wastes decompose with the formation of gases (with methane as a major constituent when the degradation proceeds anaerobically). The passage of rain and other water through the waste in landfills and dumps generates contaminated leachate and runoff. Where no collection systems are installed, landfill gases and leachates escape from the dump in an uncontrolled manner. While PCDD/PCDF have not been quantified/reported in landfill gases, they are known to occur in landfill leachates or seepage and, in some cases, nearby soils.
A large amount of PCDD/PCDF and other unintentional POPs have been deposited over the last century in landfills and dumpsites, with the largest reservoirs stemming from chlorine and organochlorine production (see Source Group 10). Landfill mining and reclamation, or excavation/remediation of landfills is a process whereby solid wastes which have previously been landfilled are excavated and processed.
The objectives of landfill mining/reclamation and excavation/remediation can be threefold:
As an example, PCDD/PCDF contaminated lime has been mined from a landfill containing residues from VCM/EDC production (Torres et al. 2012). This contaminated lime was partially used for neutralization of citrus pulp which was subsequently used as feedstuff for cattle in Europe. This resulted in contamination of milk and dairy products in several European countries (Torres et al. 2012, Malisch 2000; see example inventory 10).
The excavation of landfills for remediation purposes reduces or prevents releases of more water soluble compounds contaminating groundwater, surface water or drinking water, or being otherwise a threat because of the relatively immobile PCDD/PCDF. Excavation can also be undertaken due to cost considerations or to avoid burdening future generations.
The quantity of PCDD/PCDF in landfills being excavated is site specific and needs to be individually assessed in each case (Forter 2006, Torres et al. 2012, Weber et al. 2008a,b). The excavation and remediation activities of landfills containing wastes from organochlorine industries or other wastes contaminated with PCDD/PCDF must also consider the risks of occupational exposure to PCDD/PCDF. The excavated wastes need to be treated in an environmentally sound manner as described in the BAT&BEP Guidelines.
PCDD/PCDF emission factors for three source classes are listed in Table II.9.3. Revised or newly added emission factors are highlighted in red. Detailed information on how these emission factors have been derived can be found in Annex 53.
Table II.9.3 PCDD/PCDF emission factors for source category 9a Landfills, Waste Dumps and Landfill Mining
|9a||Landfills and Waste Dumps||Emission Factors (µg TEQ/t in residues disposed of)|
* The residues of wastes from category 1 to 8 are accounted in the respective categories.
Class 1 applies to landfills where wastes from source groups 1 to 8 are deposited.
Class 2 applies to landfilling of waste which may contain some hazardous components. A typical situation is in cases when no waste management is in place.
Class 3 applies to landfilling of non-hazardous wastes.
When assessing releases from this source category, care should be taken that no double counting occurs. This category covers wastes generated at national level that are landfilled. It does not include municipal or hazardous waste that is accounted for in other source groups or source categories, especially in:
Activity rates might be available on national level and on municipality level. In general there historical data are scarce. Additionally, the set of data for PCDD/PCDF in waste are uncertain because of the small regional coverage of these data.
There are multiple sources of uncertainty associated with the PCDD/PCDF levels in waste and the emissions from landfills. Emission factors are thus assigned a medium to low level of confidence.
Sewage is waste that is dissolved and/or suspended in water. Sewage, also called wastewater, typically includes human feces and urine, bathwater, water used in washing clothes and other items, and, in some cases, storm water run-off and industrial wastewater.
This category addresses municipal sewage that is collected and transported to sewage treatment facilities. Untreated sewage that is collected and discharged directly to surface water, such as rivers, lakes and oceans, is addressed in source category 9c Open Water Dumping. Wastewater and wastewater treatment from industrial production is addressed in source group 7 – Production and Use of Chemicals and Consumer Goods.
Sewage treatment ranges from simple removal of large solids by coarse screening to further solids removal in settling ponds, biological and chemical treatment, disinfection, reverse osmosis filtration and other advanced technologies. These commonly used sewage treatment methods produce an aqueous effluent and a solid residue, sewage sludge. PCDD/PCDF concentrations in treated effluent are ordinarily low. However, when chlorine is used to disinfect treated effluent, PCDD/PCDF concentrations can increase, in some cases, by as much as 50-fold (Pujadas et al. 2001). Most of the PCDD/PCDF found in sewage and, subsequently, in treated effluent and sewage sludge originate in other processes or products. For example, PCDD/PCDF may occur in sewage because they have been washed from clothing and other textiles treated with PCDD/PCDF-contaminated biocides or dyes and pigments (see source category 7d), due to the entry into sewers of runoff of atmospheric deposition of PCDD/PCDF from combustion sources (Gihr et al. 1991), or due to discharges into sewers of untreated industrial wastewater.
For many years, PCDD/PCDF have been reported in sewage sludge of many countries (Clarke et al. 2008). Decreasing trends have been reported in countries such as Germany and Austria, as well as in Spain (Martinez et al. 2007, De la Torre et al. 2011). The management of sludge can also result in releases of PCDD/PCDF. For example, land application of sludge can lead to increased PCDD/PCDF in soils (Molina et al. 2000), in certain vegetation grown on sludge-treated soils (Engwall and Hjelm 2000), and in the tissues and other products of animals that forage on PCDD/PCDF-contaminated soils (Schuler et al. 1997, Rideout and Teschke 2004). Likewise, sludge buried in landfills may contribute to PCDD/PCDF in landfill leachates (De la Torre et al. 2011).
Untreated sewage from remote, undeveloped and non-industrialized areas is expected to have relatively low PCDD/PCDF concentrations. Low concentrations may be also expected in countries with stringent controls on discharges of industrial wastewater to sewers, effective controls on the use of PCP, other biocides and colorants on textiles, and bans on the use of chlorine-bleached toilet paper. Higher levels can be expected in urban areas with mixed industry and use of PCDD/PCDF-contaminated consumer goods. Discharges of untreated industrial wastewater to public sewers can cause very high levels of PCDD/PCDF in sewage sludge (for reference, see categories7b to 7e Chemical industry).
With more advanced treatment – such as biological and chemical treatment - most PCDD/PCDF are likely to be concentrated in the sludge. The amount of PCDD/PCDF in the effluent is likely to be influenced by the amount of suspended solids remaining in the effluent.
PCDD/PCDF emission factors for three source classes are listed in Table II.9.4. Revised or newly added emission factors are highlighted in red. Detailed information on how these emission factors have been derived can be found in Annex 53.
Table II.9.4 PCDD/PCDF emission factors for source category 9b Sewage and Sewage Treatment
|9b||Sewage and Sewage Treatment||Emission Factors|
|Classification||Air||Water (pg TEQ/L)||Land*||Product = Residue (µg TEQ/t d.m.)|
|1||Mixed domestic and specific industrial inputs**||NA
|2||Urban and industrial inputs||NA
ano sludge removal, bwith sludge removal
* Use EFPRODUCT when residue (sludge) is applied to land.
** for those emissions which are not covered in source group 7.
Note: the emission factors are given in pg I-TEQ/L of treated effluent and in μg I-TEQ per ton of sewage sludge (dry matter = d.m.) generated.
Class 1 should be applied where, besides normal domestic effluents, industrial effluents with a potential to contain PCDD/PCDF as described for categories 1 to 8 are collected in the same sewer system.
Class 2 should be applied for urban, industrial areas without specific potential to contain PCDD/PCDF.
Class 3 should be applied to remote areas with no known PCDD/PCDF sources and urban areas with only domestic inputs.
Activity rates on production of sewage sludge might be available on national level and on municipality level. One challenge is to assign which facilities to classify as class 1 with specific industrial input. A national survey for PCDD/PCDF in sewage sludge is helpful to facilitate source classification. A regular survey for sewage sludge is not recommended or might be performed every 5 or 10 years. For facilities with elevated levels (above 30 ng TEQ/kg), source(s) might be traced, and measures for release reduction introduced.
The emission factor values are assigned a high confidence level, based on the geographic coverage of available datasets and consistency among the results of the various studies.
Open water dumping is the practice of discharging untreated wastewater or other wastes directly into surface waters, i.e. rivers, ground water, lakes or oceans.
PCDD/PCDF emission factors for three source classes are listed in Table II.9.5.
Table II.9.5 PCDD/PCDF emission factors for source category 9c Open Water Dumping
|9c||Open Water Dumping||Emission Factors (µg TEQ/m³)|
|1||Mixed domestic and industrial wastewater||NA||0.005||NA||NA||NA|
|2||Urban and peri-urban wastewater with little or no industrial input||NA||0.0002||NA||NA||NA|
Class 1 should be applied, if the wastewater being discharged includes both domestic and industrial wastewater with a potential to contain PCDD/PCDF or stormwater runoff from urban, peri-urban or industrialized areas.
Class 2 should be applied for urban and peri-urban areas with little or no industries.
Class 3 includes remote areas with no known PCDD/PCDF sources.
Composting is the biological decomposition of biodegradable solid waste under controlled predominantly aerobic conditions to a state that is sufficiently stable for nuisance-free storage and handling and is satisfactorily matured for safe use in agriculture (Diaz et al. 2005). Feedstocks for composting include a wide variety of materials, e.g., kitchen and garden waste, sewage sludge, agricultural crop residues, some industrial wastes, animal manures and human excreta.
The average PCDD/PCDF level in compost in Europe is around 10 ng TEQ/kg (Brändli et al. 2005). In Brazil, organic composts (separated at source) had an average PCDD/PCDF content of 14 ng TEQ/kg (Grossi et al. 1998). However, composts produced from mixed waste where organic fractions have been separated after collection (“grey compost”) had an average of 57 ng TEQ/kg, with a maximum of 150 ng TEQ/kg in metropolitan areas, and an average of 27 ng TEQ/kg in small towns (Grossi et al. 1998). Compost impacted from pulp and paper sludge using Kraft process also had high values (99 ng TEQ/kg). These “grey” composts with levels of 50 ng TEQ/kg and higher are not considered suitable for agriculture or horticulture in Europe. However, standards differ among other regions and countries.
PCDD/PCDF emission factors for two source classes are listed in Table II.9.6. Revised or newly added emission factors are highlighted in red. Detailed information on how these emission factors have been derived can be found in Annex 53.
Table II.9.6 PCDD/PCDF emission factors for source category 9d Composting
|9d||Composting||Emission Factors (µg TEQ/t d.m.)|
|1||Grey compost (organic wastes separated from mixed wastes)||NA||NA||NA||50||NA|
|2||Clean compost (Organic wastes separated at source or green material)||NA||NA||NA||5||NA|
* Compost is finally applied to land
Class 1 should be applied when the organic fraction is separated from mixed wastes and then composted. Such composts also contain higher levels of heavy metals and plastics.
Class 2 should be applied for compost where organics (kitchen/market waste, vegetables/fruit etc.) have been separated at source or green materials have been used.
Activity rates on production of compost might be available on national level and on municipality level. The activity rates of composting on household level might not be available from national statistics but might need a survey or an expert judgment.
The emission factor values have been assigned a high level of confidence. Nevertheless, uncertainties exist where organic industrial residues are used (e.g. from pulp and paper industry).
The estimate of PCDD/PCDF releases from waste oil treatment is difficult for several reasons. Firstly, there is no clear definition of “used” oil or “waste” oil. For the purpose of the Toolkit, waste oils (or used oils) are defined as any petroleum-based, synthetic, or plant- or animal-based oil that has been used. Waste oils may originate from two large sources: used industrial oils, and vegetable or animal waste oils. Among the industrial waste oils, three main oil streams can be identified: industrial oil (for example, hydraulic oil, engine lubricant, cutting oil); garage or workshop oil; and transformer oil. More information can be found in the BAT&BEP Guidelines.
Waste oils have been found to be contaminated with PCDD/PCDF and PCB. PCB-containing oils from transformers are addressed in source category 10f.
At present there is no evidence that PCDD/PCDF or PCB are newly formed in waste oil refineries. The data available indicate that PCDD/PCDF and PCB released from waste oil refineries or waste oil handling and management plants are from the industrial, intentional production of PCB or chlorobenzenes that are present in waste oils either by contamination in the synthesis process (of these chemicals) or have become contaminated during the use phase or earlier recycling processes. More information can be found in the BAT&BEP Guidelines.
Waste oil collected in countries will end up in other processes and has to be included in the categories on waste incineration (1a and 1b), power plants (3a), domestic heating and cooking (3e), cement kilns (4a), brickworks (4c), asphalt mixing stations (4f), or transportation (5d).
The management of PCDD/PCDF or PCB contaminated oils may result in human exposure of the personnel collecting or otherwise handling the oils. During storage and handling, diffuse emissions may occur. Contamination of the environment may also result from spills. Residues from recycling operations may contain high concentrations of PCDD/PCDF. Improper disposal may result in contamination of land or water. It can be assumed that a site- or process-specific evaluation has to be performed.
Presently, no emission factors can be given with respect to any of the release vectors.