Bio-pretreatment of municipal solid waste prior to landfilling and its kinetics

The conventional landfilling does not promote sustainable waste management due to uncontrolled emissions which potentially degrade the environment. Pretreatment of municipal solid waste prior to landfilling significantly enhances waste stabilization, reduces the emissions and provides many advantages. Therefore, pretreatment of municipal solid waste methods were investigated. The major objectives of biological pretreatment are to degrade most easily degradable organic matters of MSW in a short duration under controlled conditions so as to produce desired quality for landfill. To investigate the suitable pretreatment method prior to landfilling for developing countries four pretreatment simulators were developed in the laboratory: (i) anaerobic simulator (R-1), (ii) aerobic pretreatment simulator by natural convection of air (R-2), (iii) aerobic pretreatment simulator by natural convection of air with leachate recirculation (R-3) and (iv) forced aeration and leachate recirculation (R-4). During the pretreatment organic matter, elemental composition, i.e., carbon, hydrogen, nitrogen and settlement were determined for bench scale experiments. A two-component kinetic model is proposed for the biodegradation of organic matter. Biodegradation kinetic constants were determined for readily and slowly degradable organic matter. The biodegradation of organic matter efficiency in terms of kinetic rate constants for the pretreatment simulators was observed as R-4 > R-3 > R-2 > R-1. Biodegradation rate constants for readily degradable matter in simulators R-4 and R-3 were 0.225 and 0.222 per day. R-3 and R-4 simulators were more effective in reducing methane emissions about 45% and 55%, respectively, as compared to anaerobic simulator R-1. Pretreatment of MSW, by natural convection of air with leachate recirculation R-3 is sustainable method to reduce the emissions and to stabilize the waste prior to landfilling.