Degradation of municipal solid waste in aerobic bioreactor landfills.

The biodegradation of municipal solid waste (MSW) was investigated in simulated bioreactor landfills under aerobic conditions. The bioreactors were operated to determine the amount of leachate recirculation and municipal wastewater sludge addition required to optimize waste degradation. The leachate generated was recycled over 47 weeks, leachate samples were collected on a weekly basis and analyzed for pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), Total Kjeldahl Nitrogen (TKN), and ammonia nitrogen (NH3-N). The temperature of the MSW in the bioreactors was measured on a daily basis. Leachate and sludge were added at the rates of 5 l wk(-1) to 15 l wk(-1) and 0.5 l wk(-1) to 1.5 l wk(-1), respectively. Within 27 weeks enhanced MSW degradation was observed at a leachate recirculation rate of 15 l wk(-1) (855 mg l(-1) of MSW d(-1)) and sludge addition rate of 1.5 l wk(-1) (85 mg l(-1) of MSW d(-1)). During this period, the COD concentration in the leachate dropped significantly. A reduction in the leachate recirculation and sludge addition rate increased the waste stabilization period up to 45 weeks.