Obstacles to Progression of Landfill Bioreactor Technology in Australia

Transcription

1 Obstacles to Progression of Landfill Bioreactor Technology in Australia CONTACT Elizabeth C. Pattison and Samuel T.S. Yuen, The University of Melbourne Samuel T.S. Yuen, Department of Civil & Environmental Engineering, The University of Melbourne, Parkville, Victoria Tel: , Fax: , s.yuen@civenv.unimelb.edu.au EXECUTIVE SUMMARY Landfill bioreactors accelerate stabilization and settlement of municipal solid waste. The rapid decomposition of waste occurs due to enhanced microbiological processes, which improve the stabilisation of waste and enhance the production of biogas. The biogas produced can be captured and utilised for renewable energy production that greatly reduces the emission of greenhouse gases into the atmosphere. The rapid decomposition of waste also helps to bring forward the inert state of a landfill in a relatively shorter period of time, thus avoiding the longer-term environmental risks associated with dry landfills. The technology therefore has the potential to provide a sustainable development option for the waste management industry. Evaluation into current bioreactor technology has proven that the practice enhances waste stabilisation whilst meeting a similar or better cost benefit analysis as conventional landfills, when intergeneration equity is taken into account. Landfill bioreactors in Australia are still in their experimental stages. There are only two full scale sites that are currently being developed. The Ti tree site situated in Queensland has started receiving waste, and the Woodlawn Bioreactor situated in Tarago, New South Wales has been operating since September This landfill bioreactor receives waste from Sydney, and is producing biogas, which is used to generate renewable electricity. Both bioreactors enable the efficient production of green energy from what would otherwise be waste material. In doing so bioreactor landfills has the potential in changing the balance of the waste hierarchy by increasing resource recovery. The analysis of expert opinions from the waste management industry within Australia, predominately in the State of Victoria, has been conducted to determine the obstacles to progression of landfill bioreactors, in particular leachate recirculation. These opinions have been sought through surveys of landfill operators and waste management consultants. Regulators opinions were also sought from each State and Territory of Australia. From the survey there is a general consensus amongst all experts interviewed that leachate recirculation is a viable form of enhanced waste degradation. However the survey data also highlighted conflicting views among operators, consultants and regulators. The areas of discrepancy relate to potential environmental impacts and competency of landfill facilities and operators when applying leachate recirculation. All operators view their site as being competent to receive leachate recirculation, however consultants and regulators feel that there is not sufficient operator technical knowledge or competency to recirculate leachate. Consultants and operators view the current conservative policy and regulations as the main barrier to the progression of bioreactor technologies, while regulators indicate the lack of progression to be

2 related to policy, increased costs and potential environmental impacts. These discrepancies within the industry highlight the lack of communication within the waste management industry. This paper presents these discrepancies within the industry. The findings suggest that conservative licensing could be the predominate barrier to leachate recirculation. INTRODUCTION This paper provides a brief review of the recent development in landfill bioreactors and compares this technology with the conventional landfill approach. It also discusses the status of this technology in Australia and the related waste management policy and regulations. The paper then presents a recent study conducted to collect opinions from industry and regulators in Australia, predominantly in the State of Victoria, to ascertain the reasons for a lack of progression in landfill bioreactor technology in the country. BIORECTOR LANDFILLS VS. CONVENTIONAL LANDFILLS Conventional landfills or dry cell approach to landfill design aims to contain the waste in a permanent storage facility. Here the waste remains preserved, with slow decomposition. This artificially seals the waste to exclude water and prevent bio-degradation, which delays the formation of leachate and gas. Base liners and surface capping exclude moisture. There has been limited experience to prove the longevity of liners and containment facilities; however conventional landfills require long-term performance of the lining to prevent environmental contamination. Conventional landfills have extended post closure costs and are passing on this generations waste to future generations to deal with. In contrast landfill bioreactors optimize waste stabilization through enhanced microbiological processes. One of many advantages is reduced post closure maintenance and earlier development of the land (Reinhart et al, 2002). Figure 1 - National Greenhouse Gas Inventory Australian Greenhouse Office Recovering landfill gas to generate electricity is becoming more common. Figure 1 (AGO, 2007) shows methane generated from landfills compared to volumes that are utilised for energy production in Australia. The graph indicates that there is still a very high proportion of methane generated from landfills that is not harnessed for renewable energy production. In conventional landfills, waste decomposes at different rates due to varying moisture levels; as a result projects to recover methane for electricity generation are frequently rejected due to the unpredictability and low volumes of gas

3 generation (He et al, 2005). An advantage of bioreactor landfills is that degradation of the waste is encouraged and thus the quality and quantity ensures adequate supply for electricity generation. Through recirculating leachate, increased moisture content increases the rate of methane production making the collection and generation of electricity more economical with improved usability of waste as a renewable energy source (Borglin et al, 2004). The enhanced biodegradation in a landfill bioreactor also helps to accelerate landfill settlement which in turn creates additional disposal space. This is particularly advantageous, as landfills require large areas of space and have strict regulatory requirements for site selection. Any additional space to increase the efficiency and life span of each landfill would alleviate the ongoing pressures for another disposal site. Bioreactors have the potential to bring forward the inert state of a landfill in a relatively shorter period of time, thus avoiding the longer-term environmental risks associated with dry landfills (Yuen, 2001; Yuen et al, 2001). Research has found that there is sufficient experience and knowledge to recommend design and operation practices for bioreactor landfills (Reinhart et al, 2002). Through a cost benefit analysis relating to introducing technology to rapidly degrade waste, Clarke (2000) evaluated that there could be a positive net economic impact for bioreactor landfills given the high sum of economic benefits and the low additional infrastructure costs compared with conventional landfills. The economic benefits are: 1) enhanced methane generation thus electricity output; 2) reduced landfill size due to accelerated degradation; 3) reduced post closure costs - analysis shows that concentrations of COD and TOC in landfills reduce over time when leachate recirculation has occurred; and 4) reduced long term impacts on environment due to barrier failure. The additional costs required for landfill bioreactors are leachate distribution piping, gas collection piping and power generating equipment. The offset of these capital costs with the economic benefits results in the cost benefit of bioreactor technology. As the analysis is comparing the costing with a conventional landfill, the initial capital costs for set up and maintenance are assumed to be within the same range (Clarke, 2000). It is found that bioreactor landfills have higher private costs, but generally lower external costs than dry tomb landfills (Mery et al, 2005). The bioreactor technology however requires active landfill management, which involves an understanding of the biological, chemical and physical processes involved. Mery et al (2005) suggests that bioreactor landfills lead to higher risks during the exploitation phase (affecting the current generation who produce the waste) (However) bioreactor landfills entail lower risks during the entire post closure phase (affecting future generations not responsible for the waste) thus higher risks associated with waste degradation will require additional management and resource allocation to develop the knowledge base needed for such involved maintenance. POLICY AND REGULATIONS International Status of Landfill Bioreactors Arguably the United States is currently leading the world in landfill bioreactor research and application (US EPA 2006). Several states within the US encourage landfill bioreactor technology with the New York Code of Regulations stating that active landfill management techniques to encourage rapid waste mass stabilization and alternate energy resource production and enhanced landfill gas emission collection systems are encouraged There are 6 US states that allow bioreactor landfills, however most states approve leachate recirculation. (Reinhart et al, 2002). A 1997 survey identified that 130 landfills were practicing leachate recirculation (Gou and Guzzone,

4 1997). This is in contrast to Australia where only limited isolated trials have been approved to recirculate leachate. The Australian context Conventional landfills are predominately utilised in Australia. These are engineered containment facilities that entomb waste, which then remains inactive for long periods of time. The Victorian EPA Waste Management Policy (EPAV 2004) encourages minimisation of the development and use of landfills and diversion of waste materials for reuse or recycling instead of disposal. Waste disposal to landfill is the last option in the waste hierarchy, however waste is still entering landfills, thus optimising a landfill process and design is important. In 2004 there were policy changes in the State of Victoria for all landfills that service 500 people or more, resulting in changes in licensing requirements (EPAV 2004). The objective was to reduce smaller unlicensed landfills and replace them with a system of resource recovery and waste transfer facilities, leading to a smaller number of better designed and operated regional landfills. These large landfills service metropolitan areas, which receive the predominant volume of waste. These well designed regional landfills have high potential for bioreactor landfill applications, as their containment specifications are high, having to fulfil the design required in the EPA Best Practice Environmental Management guidelines (EPAV 2001). The guidelines ensure the protection of the environment through preventing contamination of surface and groundwater by leachate. To meet these specifications, management of the landfill would include all phases of the landfill s construction, operation, rehabilitation and ongoing after-care of the site (EPAV 2004). As a result, it is reasonable to expect the implementation of landfill bioreactors with leachate recirculation to occur in these well designed regional landfills resulting in minimal potential environmental impacts. However, the regulatory authorities within Australia remain sceptical. The Victorian EPA guideline document (EPAV 2001) explicitly states that enhanced biodegradation landfills are not considered to be acceptable practice. and it places additional demands on the liner and leachate collection system. This illustrates that legislation within Australia may be holding back bioreactor technology. As a result, landfill bioreactors in Australia are still in their experimental stages. There are only two full-scale sites that are currently being developed. The Ti tree site, in Queensland, which is still accumulating waste and the Woodlawn Bioreactor in New South Wales that has began producing biogas, and is used to generate renewable electricity (Veolia Environmental Services, 2006). THE STUDY A study into the progression of landfill bioreactors within Australia, predominately Victoria, has been undertaken through a survey of waste management consultants, landfill operators and regulators (Pattison 2006). The research focused on leachate recirculation, as it is this particular component of landfill bioreactor technology which has produced the greatest research and application. Through interviews and a pre-designed questionnaire, opinions from the waste management industry were collected to ascertain the reasons behind the limited progression of landfill bioreactors. Similar questionnaires were also sent to the regulators of each state and territory in Australia. The survey required cooperation from industry and regulators to impart their opinions regarding willingness and ability to apply leachate recirculation to accelerate biodegradation. Landfill operators were included in the survey as they are directly involved in the site management. It was assumed they are aware of the design and capacity of their landfills and the technical ability of their site personnel to conduct leachate recirculation. Waste management consultants were included due to their expertise, exposure to numerous sites and experience with both regulators and operators.

5 It is also likely that they are up to date with EPA policy and licensing requirements. Regulators were included in the survey due to their responsibility for policy, approval and licensing. All industry representatives interviewed are members of the Waste Management Association of Australia (WMAA). The survey has focused only on members of Landfill Victoria (a working group of WMAA in Victoria with focus on landfills). Twenty six landfill site managers were contacted, with 15 responses. For 3 landfill sites, more than one staff members responded to the survey. Nineteen consultants were contacted, with 9 responses. Regulators from all 8 States and Territories were contacted, with 6 responses. Given the limited samples involved in the survey, no statistic analytical tests have been conducted on the validity of the results. Thus the results can only be used to provide a limited basis in understanding the current situation and ways forward for the industry. SURVEY RESULTS Details of the study and its findings are presented by Pattison (2006). The tables below only present a summary of the results. Table 1 - Quantifiable results from Survey, Pattison (2006) Question Answer is % in favour of statement Operators Consultants Regulators If your site were to recirculate leachate, you would have concerns about potential environmental impacts. 50 NA NA The facilities at your site are capable of recirculating leachate. 100 NA NA Regulators concerns regarding leachate recirculation are not warranted NA Leachate recirculation is a viable treatment option. (*For operators surveyed this related to treatment for their site) 86* Operators do not have technical competency to recirculate leachate Given the acceptance of leachate recirculation in the US, the current barrier to leachate recirculation in Australia relates to: Policy NA Increased Costs NA Environmental concerns NA There are no incentives for industry to seek licenses to recirculate leachate. NA Note: NA in the table signifies that the question was not asked of the representative group during the study.

6 Table 2 - Qualitative results from survey, Pattison (2006) What are the factors that impede bioreactor applications within Australia? Operators Where benefits from bioreactor applications were applicable operators saw the predominant barrier to its applications as regulatory resistance, particularly resistance to approve license applications. Consultants Unanimously felt that the main factor impeding the application of leachate recirculation and bioreactor applications was regulatory resistance, and policy. The reasons generally related to a conservative approach to licensing, and doubt in capabilities of liners and collection facilities to withstand leachate recirculation. Regulators Viewed a lack of technical knowledge and scientific proof of the safety of leachate recirculation as the concerns. Potential for environmental impacts were a major barrier as well as to a lesser extent increased cost and policy. FINDINGS AND DISCUSSIONS Operators Responses All operators interviewed were in favour of recirculating leachate, however not all operators deemed it beneficial for their site with regard to enhanced stabilisation, due to the waste composition. The responses pointed to a conservative approach to approval, ambiguity in license conditions, policy and legislative resistance. None of the operators indicated that the barriers were related to financial restraints or lacking of technical knowledge and skills. All Victorian operators surveyed signifying that their current landfill site is capable of recirculating leachate. The majority also view industry technical knowledge to be sufficient for the practice. This finding is significant because in the state of Victoria, unlike Queensland and New South Wales, there are no full-scale landfill bioreactors being developed. Majority of the respondents did not feel that regulatory concerns of potential environmental impacts from leachate recirculation were warranted. The survey suggested that generally operators are aware of the possible impacts of leachate recirculation on groundwater but see that the issue can be overcome by suitable management of the landfill bioreactor. One of the benefits of bioreactors is its effect on methane production. All operators indicated that methane collected on site should be utilised for renewable energy production. Consultant Responses Majority of the respondents felt that operators currently do not have sufficient technical knowledge to implement leachate recirculation, although this has been suggested by one consultant to be due to a lack of opportunity rather than enthusiasm or competence. Respondent findings also suggested that for landfill technologies to change, current operators require additional training and leadership from experienced sources to enable the bioreactor technology to operate effectively and without environmental impacts. The technology was considered a viable form of waste degradation by consultants, with the majority of respondents supporting its application, and all respondents felt that the regulatory concerns regarding leachate recirculation were not warranted. Regulator Responses 67% of regulators surveyed felt that operators were not technically competent to implement leachate recirculation. In contrast, all regulators see leachate recirculation as a viable form of enhanced waste

7 degradation. The above could suggest that it is not the concept of bioreactor technology that regulators are against but the way it is implemented. The implementation concerns relate to potential environmental and safety issues. One regulator viewed this as the predominant barrier to leachate recirculation because current landfills do not necessarily meet the design requirements. Another regulator suggested the lack of technical knowledge of the bioreactor process and its possible implications, which incorporates a need for scientific proof of the safety of leachate recirculation. This emphasises the need for further technical forums and discussions between all aspects of the waste management community. CONCLUSIONS The study has found that the Australian regulatory body is conservative in their approach to licensing. The conservative approach adopted by regulators is related to their concerns that operators do not have sufficient technical knowledge and skills to implement new active landfill management techniques. The waste management consultants viewed regulatory constraints as the predominant reason for the lack of progress in landfill bioreactors in Australia. This perception was shared by the operators. All operators involved in the study had the opinion that their sites could have sufficient controls to enable a successful operation. No operators felt that predominant barrier to landfill bioreactors were increased costs or potential environmental impacts. The regulators had a different standpoint. They viewed the lacking of scientific evidence, increased costs and potential environmental impacts as main barriers to landfill bioreactor applications. Given the research and international applications so far have indicated that landfill bioreactors have the potential to offer significant advantages over the conventional dry tomb storage approach, the regulators should at least exercise an open-minded attitude to communicate with researchers and industry. There are nevertheless 2 full-scale bioreactors that have recently been approved in Australia in the states of Queensland and New South Wales. These pilot sites with time would provide evidence to prove if the conservative approach currently adopted by the regulators is warranted. REFERENCES AGO (2007). National Greenhouse Gas Inventory 2005, Australian Greenhouse Office, Commonwealth of Australia. Borglin, S.E., Hazen, T.C., Olenburg, C.M., & Zawislanski P.T.(2004). Comparison of Aerobic and Anaerobic Biotreatment of Municipal Solid Waste. Journal of the Air and Waste Management Association 54, Clarke, W.P., (2000). Cost-benefit analysis of introducing technology to rapidly degrade municipal solid waste. Waste Management and Research 18, EPAV (2001). Best Practice Environmental Management: Siting, Design, Operation and Rehabilitation of Landfills, Environment Protection Authority, Publication 788, October EPAV (2004). Policy Impact Assessment: Waste Management Policy (Siting, Design and Management of Landfills), Environment Protection Authority, Publication 968, December 2004.

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