Biogas Generation from Sanitary Landfill Leachate

MELLO, V.F.B.¹, LIMA, V.F. ¹, HOLANDA, S.H.B.², FERREIRA, J.M.^1,3, JUCÁ, F.J.T. ²,

MOTTA SOBRINHO, M.A.^1,2

¹ Environmental Process and Technology Group – DEQ – UFPE

² Department of Sugarcane Technology - UFPB

³ Solid Waste Group – DECivil - UFPE

The use of alternative sources of energy not only contributes to environmental sustainability and for diversifying the energy matrix, which in the case of Brazil , has a high renewable portion (45%). The possibility of obtaining energy when treating an effluent has been a current focus of fundamental and applied research, and the last  developed by companies or partnerships with research institutions. The anaerobic degradation process generates a blend rich in methane (70 to 50%) to degrade solid or liquid contaminants. The generation of biogas from landfills is already a reality, with several installations in operation in the country. However the treatment of leachate (liquid derived from the anaerobic degradation diluted in water from the landfill itself) is one of the main barriers to the installation of this type of disposal for waste, for its complexity , toxicity and recalcitrance. To estimate the potential for generation of biogas from waste is generally used the BMP test (Biochemical Methane Potential), which assesses the biodegradability of waste from the total production of biogas (containing mainly CH₄ and CO₂) under controlled conditions, knowing the initial composition of the waste and the conditions they are subjected to biodegradation (ALVES, 2008). However, the increase of pressure inside the bottle can shift the equilibrium of the reaction, underestimating the generation of biogas. It is noteworthy that the ratio F:M. (organic load/microorganism), the head-space of the bottle and the pH (which should be close to neutrality) may influence the production of biogas. Consequently, this study aimed to evaluate the influence of parameters mentioned in the production of biogas through a 2³ full factorial design in BMP trials. All experiments were performed in triplicate. The leachate used was collected from the landfill leachate treatment unit of Muribeca and presented a COD of 3,066 mgO₂.l^-1, and pH of 8.3, which was adjusted according to the planning (6.0, 7.5, 8.5). The anaerobic sludge was provided by Brazil Kirin brewery (Guabiraba - PE). In parallel, a blank experiment, with only a white sludge, was realized to evaluate the biogas production with the organic matter of the sludge itself. In order to minimize the pressure effect, every time that it reached 0.8 bar, there was release of the bottle. Under the condition of 50 ml of sludge (VSS = 152.27g.L^-1) leached in 50 ml of pH 7.5, the production rate was 9.7 ml.d^-1 and the total volume of biogas generated was 277 ml. The methane concentration in the biogas from leachate was 67% and in the bottle with only anaerobic sludge was 55%.

Keywords: production of biogas, BMP trials, anaerobic biodegradation.