SEQUENTIAL DRY BATCH ANAEROBIC DIGESTION OF THE ORGANIC FRACTION OF MUNICIPAL SOLID WASTE
Nguyen Quang Huy
Solid waste is all the waste arising from human and animal activities that are solid and discarded as useless or unwanted. Integrated solid waste management includes waste collection, sorting, and treatment methods such as recycling, composting, incineration, anaerobic digestion and landfill. The problems associated with direct disposal in landfill are the possibility of ground and surface water contamination by the leachate, air pollution
due to emission of landfill gases such as methane, carbon dioxide causes global warming. Aerobic and anaerobic treatment have been used as pre-treatment technologies before disposal. The anaerobic digestion generate energy in the form of methane and produces stable residue, which can be utilized as fertilizer. This study aims to investigate the dry batch Bio-mechanization of Organic fraction of Municipal Solid Waste (OFMSW) as a pretreatment prior to landfill. In this study, batch dry fermentation of solid waste was used as a method of pretreatment of OFMSW prior to landfill. Furthermore the performance of the dry batch anaerobic digestion process of OFMSW was investigated in pilot scale experiments. It found that circulation leachate reactor produced about 5 time more methane than the no circulation reactor, indicating that leachate circulation has a positive effect on methane recoveries. The specific methane yield as obtained with in three SEBAC reactors are 42, 230 and 100 L CH4 /kg VS in 96 days and 45 days operation, respectively with the no circulation leachate reactor, direct circulation reactor and exchange leachate reactor. These values correspond to the 12%, 66%, 29 % process efficiency calculated based on the laboratory BMP assay. it also found that biogas production was strongly dependant on and very sensitive to the fluctuation of ambient temperature. The results of this experiment indicated that sequential batch operation investigated here overcomes the disadvantages of a batch reactor by successfully starting a digester by inoculation with leachate.