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An assessment of the province's compost processing facilities has taken place five years after the introduction of the organics waste ban. Seventeen active facilities were visited in the company of NSDEL staff for interviews, photographs and a compost sample that was tested for maturity. Comments and findings were subsequently consolidated into ten conclusions and recommendations accompany this document.
Participation in the diversion and treatment of organic waste is highest on mainland Nova Scotia due in part to residential curbside collection programs. Increased diversion can be achieved through improving the collection infrastructure (particularly in Cape Breton), increasing enforcement practices (particularly in the apartment and ICI sectors), and of course maintaining an imaginative and aggressive educational program.
In general, the compost facilities are adequately managing the organic decomposition process, however most facilities have found that they are unable to produce a mature product in the designed time frame of 6-8 months and have instead found the process has typically taken at least one year. Although uses have been found for the immature product, the material is generally undervalued. In addition, some plants have been challenged to achieve acceptable outdoor air quality standards, while all indoor facilities are operating in an environment that does not regulate indoor air quality in terms of biological agents.
The compost industry will continue to advance through the production of a consistent, high quality and stable product. This can be realized through: applying a more rigorous stability test; instituting more frequent organic collection schedules; delivering less contaminated feedstock (particularly plastic film); maintaining a strong educational program; and retaining the material on-site longer, or accelerating the curing phase of the compost process. A continuation of further exchanges of information and policy between compost operators and municipal and provincial employees will also contribute to the industry's success.
Since the ban on organic material from landfills was imposed in 1998, over 18 operating permits have been issued to compost plants throughout Nova Scotia and over 100,000 tonnes of organic waste are now being diverted from landfills annually. These compost facilities engage a range of technologies, from simple static piles to automated in-vessel systems, and process a range of feedstocks, from industrial source-separated pure organic streams, to the variety of organics found through residential curbside collection programs. As the industry has grown, feedstock and operational issues have continued to evolve.
The following study provides an updated, consolidated report on the state of centralized compost facilities within the province and how they are faring within the context of the provincial program from the perspective of the operators as well as the regulators. The report also serves to encourage improved composting practices and provides direction in terms of policy refinement and educational development.
In addition to the systems analysis, the study also includes an assessment of compost maturity from samples produced at all operating plants within the province. Currently, all operations must produce a final product that complies with the compost stability tests established by the Canadian Council of Ministers of the Environment (CCME) (March, 1996) and referred to in the Nova Scotia Department of the Environment Composting Facility Guidelines (March, 1998).
The CCME guidelines contain a number of criteria under four subsections that constitutes stable compost, and although some criteria can effectively and accurately measure compost maturity, there are a number of criteria that fail to adequately identify immature compost. In fact, compost samples can pass one of the four subsections and fail the remaining three subsections and still is considered mature. On this basis, an earlier study by Bio-Logic Environmental Systems to NSDEL on October 22, 2002 reported that the current design of the CCME guidelines to evaluate compost maturity is not rigorous enough, and a substantial amount of relatively unstable compost is presently being removed from sites throughout the province. A copy of this past study is attached as Appendix A. These tests are presently under review with a particular interest in using the rate of oxygen uptake (or carbon dioxide production) within compost as the sole means of assessing compost stability in the future. The present study includes a maturity analysis of compost from operating plants using the rate of carbon dioxide production. The results indicate the number of plants currently producing stable product, and also quantifies the relative degree of immaturity from operations that do not presently produce a stable product. The project's terms of reference that summarize the intended activities are found in Appendix B.
The purpose of this evaluation is, therefore, to advance the development and management of organic waste operations, education, policy and product development through the following objectives:
In 1998, Nova Scotia began its campaign to lead North America in organic waste policy and processing. The proposed assessment will articulate the current state of centralized composting and provide recommendations to ensure that the province continues to champion the environment and remains at the forefront of responsible organic waste management.
Accompanied by a field representative of the Department of Environment and Labour, an interview took place with plant operators at each permitted site within the province in order to assess the state of organic waste management within their plant. A compilation of the operational features of each facility took place in addition to the identification of key operational issues that presently impact process performance at each facility, including an assessment of key feedstock issues that impact product quality. Each NSDEL field representative was also asked to contribute to the assessment by offering relevant comments on appropriate regulatory issues. The questions considered during the interviews are found in Appendix C.
A compost sample was also obtained from the most mature material at each site in order to perform Solvita (CO2 and NH3) tests in addition to a carbon dioxide production test that was converted into an oxygen uptake rate. The Solvita test is a commercial test marketed by Wood's End Laboratory Inc. (Mt. Vernon, Maine), while the carbon dioxide production test was performed by personnel at Wood's End using CO2 absorption and titration techniques. The oxygen uptake rate was then compared against the provincial standard for mature compost of 150 mg O2/kg dry organic matter per hour to determine the number of facilities producing product above this threshold. The oxygen uptake rate was also compared with the Solvita CO2 test to determine if there was a strong correlation between the two test techniques.
Finally, digital photographs of all sites were taken for future promotional/educational purposes. The pictures describe an assortment of systems that treat a variety of organic wastes and capture the dynamic nature of centralized composting in Nova Scotia.
The original list of permitted compost facilities is itemized in Table 1. All facilities were considered fully operational with the exception of the Amaranth facility (no longer in operation), the Atlantic Country Composting site (just beginning to process waste) and the sites at Beechhill, Baddeck, and West Arichat (insufficient quantities to generate a temperature above ambient conditions). The categorization of the facilities including the nature of the feedstocks is shown in Figure 1. All facilities took part in the survey with the exception of Miller Waste Ltd., who declined to participate. The results of the surveys and the digital photographs accompany this document in an electronic format.
Solvita tests were carried out on samples from all sites with the exception of the Amaranth facility (no longer in operation), B.A. Frasier Lumber Ltd. (site inaccessible for sampling) and the Campsite Environmental operation (material still in active state of decomposition). A vermi-compost sample was substituted for compost from the Atlantic Country Composting site, since its compost operations were just beginning. The Solvita test results are posted in terms of carbon dioxide (Figure 2) and ammonia (Figure 3) evolution.
In addition to the Solvita CO2 test, all samples were also tested for carbon dioxide evolution using more exacting laboratory techniques, with the results translated to an oxygen uptake rate and compared with the provincial standard of 150 mg O2/kg organic matter-h. A comparison also took place between the Solvita test results and the oxygen uptake rate to determine if there was a strong correlation between the two evaluation techniques. The results are provided in Figure 4.
In the assessment of the survey findings and the test results, a number of substantive issues were identified. In order to provide suitable focus, these issues were consolidated in terms of the following four key subjects.
The overall diversion rates (including organic wastes) for regions within the province in fiscal 2001/2002 are shown in Table 2. These regions represent 55 municipalities, many of which have achieved a diversion of 50%. There has, however, been no municipality
Table 1. Original list of Permitted Compost Facilities by Region.
| Region 1(Cape Breton) | Municipality of Victoria Baddeck Landfill B.A. Frasier Lumber Ltd. Richmond Organics Composting Facility (West Arichat) |
| Region 2(Eastern) | Guysborough County Landfill Beechhill Landfill Site (Antigonish) Atlantic Country Composting (T.E. Boyle) Pictou County Solid Waste Management Composting Facility |
| Region 3(Northern) | Municipality of the County of Colchester Composting Facility Fundy Compost Inc Cumberland Composting Facility |
| Region 4(Halifax) | Miller Waste Ltd. New Era Farms Ltd. Kel-Ann Organics Property Operations HRM Cowie Hill Depot Compost Yard |
| Region 5(Valley) | Northridge Farms NS Ltd. Amaranth Cooperative Enterprise Ltd. |
| Region 6(South Shore/West Hants) | Lunenburg Regional Recycling and Composting Facility Louisana Pacific East River |
| Region 7(Western) | Yarmouth Composting Facility (H&H Composting Facility) Campsite Environmental |
that has reached the diversion rate of 50% without the inclusion of curbside organic collection as a component of their waste management strategy.
Of the twenty permitted facilities within the province, fifteen are handling regular quantities of organic waste at this time and no facility is at full capacity, although daily maximum deliveries are sometimes exceeded. In addition, with the exception of the Guysborough facility (which receives a considerable amount of its organic waste from the Town of Antigonish), there are no active centralized compost facilities of consequence east of Pictou. This is in part due to the absence of infrastructure (such as organic curbside collection in some regions), the lack of participation by the ICI sector in source-separating organic wastes, and the presence of an MSW incinerator in Sydney, where the greatest concentration of organic waste in these regions resides. A higher degree of participation in organic waste diversion and compliance with the law could be achieved through further dialogue (cost-benefit analysis) with the many regions of the province that have effective collection and treatment systems in place.
In regions where the infrastructure for compost collection is already in place, increased participation and diversion could be realized through: (a) stronger enforcement initiatives (particularly within the ICI sector including apartment owners), (b) increasing the profile of organic waste management in educational initiatives and (c) increasing the frequency of organic waste collection. Responsible waste management practices within the ICI sector and among apartment owners in particular are often deflected due to the habits of their employees or residents and the practices of waste haulers. Despite this confusion, ICI managers and apartment owners are ultimately accountable for the actions of their operations and with a firm and deliberate mandate, and appropriate educational material; the responsibility to comply would be clearly articulated.
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Increasing the frequency of organic waste collection would reduce residential complaints, as well as provide the compost facilities with a more manageable feedstock. With innovative planning and promotion, more frequent collection of organics could be realized with little incremental cost by placing more emphasis on the need to collect organic waste (due to its tendency to create odours and attract pests) than on the need to collect refuse and even recyclables. Such a move places wastes in the proper perspective- it is the organics that create the predominant nuisance in wastes, not the refuse. The compromise towards more frequent collection of organics and less frequent collection of other wastes/resources is also self-policing in that residents would be more inclined to participate in the more frequent removal of the waste stream component that is the most troublesome. Frequent collection of organics maintains a high profile on source-separation, reduces the complaints from residents (particularly in the summer), provides a more manageable feedstock for plant operators, and may reduce the odour produced from the front-end of compost plants. |
Due to the relatively new industry of composting within the province, and despite the fact that compost operations have a naturally high concentration of bioaerosols, there are no standards for air quality within enclosed compost facilities. In fact, the reference that the province uses for maximum allowable concentrations of airborne contaminants (The American Conference of Governmental Industrial Hygienists) does not include bioaerosols. A number of studies of compost facilities within the province have identified the presence of (at least) Aspergillus fumagatus, Aspergillus flavus and Penicillium chrysogenum as mycotoxin producers (Seatech Ltd. (2000); Maritime Testing (1985) Ltd. (2001); RPC (2002)). These organisms and the chemicals they produce have been linked to the development of respiratory damage in humans. Although there are a number of compost facilities in which employees wear protective masks, the policy among plants is not consistent. The development of an appropriate policy could be completed inexpensively through a comprehensive literature search, an investigation of the regulatory regime elsewhere in the world and consultation with the many compost operations that have had tests completed.
Due to the variety of aspects associated with product quality, the subject was subdivided into a number of essential issues.
Without exception, the compost produced from all facilities is being utilized. The range of applications, however, varies- from simple landfill cover, to soil blending, to residential use through give-aways and sales. On average, the value of bulk compost remains comparable to topsoil at approximately $10-15/yd3 despite the more nutritious and soil-enhancing properties that a stable product possesses over typical topsoil. Thus, although markets have been established, the material generally remains undervalued, with current suppressed prices possibly due in part to the relative degree of compost immaturity at the plant gates.
Compost maturity was quantified in terms of the Solvita and carbon dioxide production tests. Of the 17 sites tested, only 8 had product on-site that was considered stable in terms of both the Solvita test (a reading of 5-8) and the oxygen uptake test (<150 mg O2/kg dry organic matter-hour). Two of these operations were leaf and yard waste facilities, three were essentially inactive or under-utilized, one was a vermi-compost sample, and only two were active source-separated MSW sites. The common aspect of all sites possessing mature compost was that the product had remained on-site for well over one year. If the link between price and maturity is legitimate (Section 5.3.1), a significant aspect of increasing the value of compost, therefore, lies in increasing the degree of maturity prior to market. Existing (and future) operations should be encouraged to either accelerate the curing process through increased aeration and mixing, and/or consider managing the material (under cover if possible) on-site for a longer period of time.
The existing criteria that determine compost maturity are listed in Table 3. Of the four tests that exist, samples can pass one test, yet fail three tests and still be considered mature enough to move off-site. In addition, many of the tests (C:N ratio, germination test, residence time-on-site) have little scientific merit in assessing stability. The C:N ratio is more a function of the feedstock type, the germination test only requires a growth rate of 50% of the control sample, and the residence time-on-site does not ensure that adequate aeration techniques are practiced. Although the measurement of oxygen uptake (or its corollary, carbon dioxide production) is, like the other tests, an indirect means of quantifying the degree of stabilization, it is perhaps the closest representation of stability. This is because a healthy microbial community, in the presence of unstable organic waste, will undoubtedly proliferate, which includes the subsequent increased respiration habits of a more active microbial community. Thus, although the test does not actually measure the amount of readily available organic waste, it does indicate the vitality of the microbial community that will only be substantive in the presence of a large source of food (fresh organic waste). The Bureau de Normalisation du Quebec (BNQ), a standards board within Quebec, has removed most of the recognized stability criteria in favour of oxygen uptake as the sole measure of stable compost. Bagged and bulk compost must have oxygen uptake rates of less than 300 and 500 mg O2 /kg-h respectively in order to be considered stable.
Table 3. Compost maturity criteria in Nova Scotia (NSDOE, 1998).
| One of the following sets of criteria must be met to qualify as mature compost: | |
| Set 1* | - C:N Ratio must be less than or equal to 25:1 - An oxygen uptake rate of <150 mg O2 /kg organic matter-hr - Cress and radish germination shall be >90% of the control sample and plant growth shall be greater than or equal to 50% of the control sample |
| Set 2 | - Compost must be cured for greater than or equal to 21 days - Compost will not reheat to >20oC above ambient temperature |
| Set 3 | - Compost must be cured for greater than or equal to 21 days - Organic matter reduction > 60% by weight |
| Set 4 | - Compost cured (post-thermophilic) for 6 months in aerobic environment |
In discussing the application of standards to compost products, there have also been arguments in favour of standards that are determined based upon the nature of the receiving environment, or the crops that are being supported (despite the much more complex approval and enforcement process required). The concept of product differentiation based on feedstock type and intended use holds some merit in dealing with quality content issues such as metals and organic constituents, but would be less appropriate in terms of compost maturity. Stable compost of any origin provides a beneficial soil amendment that supports an active soil ecosystem through the slow exchange of minerals and non-metals. Unstable compost, in any application, robs the soil of oxygen, diverts microbial communities and associated nutritional elements from soil-building activities to organic deconstruction, and produces more unstable intermediate compounds in the process. A common threshold that is independent of the application or the nature of the feedstock is therefore recommended.
In general, most compost facilities still considered contamination to be of some concern, but in general, have found that the degree of contamination is dropping. Plastic film is the predominant contaminant, followed by plastic coated paper products (such as coffee cups), rigid plastic, metal and glass. A continued emphasis on reducing the amount of plastic in the organic waste stream should remain part of any educational program that in turn would be followed by some measure of enforcement. Although enforcement (and subsequent penalties) is not the preferred option to increase diversion or reduce contamination, it remains a necessary component (particularly within the ICI sectors) in achieving successful compliance and serves as a warning to businesses and residents alike.
The use of "compostable" plastic-like bags is practiced in some municipalities, particularly in the ICI sector that uses the bags as liners in green bins to avoid continuous cleaning. The bags, however, create a number of issues arising from their use. From a processing perspective, the rate of decomposition of these bags is reported to be slower than that of the organic wastes they contain. In addition, use of these bags can create confusion among staff sorting material, particularly from residential properties, since there is often no obvious means to tell compostable and non-compostable bags apart. If it is the wish of municipalities to continue accepting compostable bags at compost plants, some measure of engagement/research should take place with the bag supplier to either prove or disprove the purported rate of decomposition of compostable bags. In addition, compostable bags must be clearly identifiable, or at least the operator of compost facilities must be made aware of those waste producers using compostable bags.
The measurement of compost stability using the Solvita test and the carbon dioxide production test (recalculated as oxygen uptake rate) provided evidence that the correlation between the two tests was not high. Each increase in the Solvita scale was equivalent to an approximate drop of 50 mg O2 /kg dry organic matter-hr (Figure 4). The comparison did indicate a closer relationship between lower Solvita carbon dioxide contents (higher colour-coded results) and lower oxygen uptake rates. The test therefore appears to be more accurate at determining stable material than in determining the degree of instability in unstable compost (lower colour-coded results).
In order for the provincial and municipal programs to become more successful, a more unified approach between all stakeholders and programs is encouraged, which would contribute to improved long-term planning. As an example, the provincial directive to establish only second-generation landfills within the province by Dec. 31, 2005 should form a key element in the development of future plans for all waste streams since the initiative creates budgeting concerns and impacts plans for refuse, recycling and organics collection and management in the future. Continuing to develop a planning process that integrates the management of all waste streams that are banned from landfills at present or in the future avoids undue expenses and provides waste producers with ample opportunity to prepare for changes in practice or policy. Provincial/municipal units must continue to improve consistency between policy, infrastructure, education and enforcement.
In addition, municipalities presently apply inconsistent fee schedules that do not encourage organic waste disposal- some municipalities are still not charging a tipping fee for garbage, yet charging for organics disposal, while others charge the same rate for organic and refuse disposal. Despite the variation in regional operations, stakeholders that work towards standardizing fee schedules that favour composting and recycling will eventually experience higher diversion rates and greater economies of scale. Such initiatives take time, but a consistent effort will continue to close the gap between the differences in waste management costs throughout the province.
The preceding discussion has identified a number of issues surrounding the organic waste management program within the province. These issues have been consolidated and developed into the following conclusions with subsequent recommendations.
Conclusion #1: Participation in the diversion and treatment of organic waste in eastern mainland Nova Scotia and Cape Breton (with the exception of the Guysborough facility) is minimal at this time. Unless organic waste diversion is increased, these regions will not achieve the provincial diversion objective of 50% and the respective landfills will continue to be burdened with excessive leachate and noxious gas production. Existing compost facilities in Baddeck, Arichat and Antigonish County would require a considerable upgrade if volumes are increased, while (at least) a new facility in the greater Sydney area would have to be built if a further increase in organic diversion is to take place.
Recommendation #1: Approach the regions in question to articulate their needs in order to meet provincial diversion objectives. Assistance should be provided to these regions (at minimal cost) through the exchange of actual costs and benefits experienced in other parts of the province for education, collection and treatment of wastes. A phased-in approach to a more comprehensive organic waste management infrastructure in these regions should commence, but only as existing facilities in the province begin to experience an improvement in product quality (see 6.3 Product Quality).
Conclusion #2: Many plant operators have found the delivered organic material to be of inferior quality when picked up on a biweekly basis, particularly in the summer.
Recommendation #2: Municipalities should consider implementing more frequent organic pick-ups and (if financial circumstances dictate) less frequent collection of refuse and/or recyclables. It is suggested that a pilot project be instituted in an appropriate locale that would include an economic evaluation of the program.
Conclusion #3: Improvement in source-separation is required in all sectors but should begin within the ICI sector and among apartment owners due to their high production rates and obvious accountability.
Recommendation #3: Municipalities should aggressively pursue compliance initiatives with the ICI sector and apartment owners in a deliberate but measured manner. Managers must be informed of their accountability and their responsibility in the education and participation of their employees/occupants in responsible waste management practices and the consequences if there is non-compliance.
Conclusion #4: Most plants have not addressed issues associated with air quality within compost enclosures in which employees work.
Recommendation #4: The province should consider the need to establish minimum standards for air-borne bacterial, particulate and viral concentrations within compost buildings in which employees work. It is advised that the exercise include a literature search and a consolidation of past air quality tests at facilities throughout the province.
Conclusion #5: The product from all plants is at present generally valued appropriately, but the product is undervalued in terms of its marketing potential in a stable, mature state.
Recommendation #5: Operators should consider an incremental cost-benefit analysis in comparing the incremental investment required to produce a more mature, stable and valuable product.
Conclusion #6: Only eight out of seventeen compost plants have product on-site that is considered stable in terms of the Solvita and oxygen uptake tests. All these facilities have held their product on-site for a period greater than one year.
Recommendation #6: Operators should strive to increase the stability of their product through: (a) accelerating the rate of decomposition through improved operating conditions that are more amenable to microbial activity (greater oxygen exchange), and/or where space exists, and (b) holding material on-site (preferably undercover) for a longer period of time (at least one year). In some cases, this would require the province revising the operating permits to increase the allowable storage on-site.
Conclusion #7: Most plants do not consider contaminated feedstock as a major operational issue although plastic film remains the predominant contaminant.
Recommendation #7: Educational programs should continue to reinforce source-separation and the removal of plastic film from organic feedstocks. If the use of "compostable" plastic bags is tolerated at compost facilities, it is advised that an evaluation of these bags be undertaken to determine if they are a legitimate means of organic containment. In addition, the consistent users of these bags should be identified and accepted by plant operators before they are delivered.
Conclusion #8: The existing criteria for compost stability are not stringent enough.
Recommendation #8: The province should consider making the test for maturity more rigorous. Modifying the existing tests for maturity could include reducing the four tests that exist at present to a single respiration test (suggested), or having samples pass at least two of the four existing stability criteria. The process towards making the stability criteria more stringent should be gradual, so that operators have sufficient time to modify operating processes if necessary.
Conclusion #9: There is no strong correlation between the Solvita test and the rate of oxygen uptake.
Recommendation #9: The Solvita test can be considered as a general means to test for compost stability (more effective for stable material), but formal stability reports should still include one of the four criteria as outlined in the CCME guidelines (see Conclusion and Recommendation #8). A revised opinion on the strength of the correlation could be determined with additional sample results.
Conclusion #10: Further cooperative efforts between compost industry representatives, the province, and municipalities would advance the development of the organics waste diversion program.
Recommendation #10: Existing organizations should continue to share information and possibly equipment that is used on a periodic basis. A province-wide compost producer's network (perhaps through the Atlantic Chapter of the Solid Waste Association of North America (SWANA)) should also be established to foster the development of the industry. Finally, working towards a common tipping fee for organic waste and a higher tipping fee for refuse creates an economic incentive to compost organics and promotes more responsible management of recyclable/recoverable materials.
Maritime Testing (1985) Ltd. (2001). Guysborough County Landfill and Compost Facility Air Testing Analysis.
RPC (2002)). Air Quality Survey at Fundy Region Solid Waste Commission.
Seatech Ltd. (2000). Report for Air Quality Monitoring at the Mount William Compost Facility for the Pictou County Solid Waste Management System, Stellarton, NS.