The influence of leachate recirculation on biogas production in a landfill bioreactor

The technology of municipal solid waste treatment in a landfill bioreactor is based on a system of controlled, enhanced fermentation of organic waste, which occurs in a heap having status of bioreactor. The enhancement of biogas production is done by leachate recirculation. In a landfill bioreactor, located in Kosiny Bartosowe, Poland, with capacity of 70 000 Mg of municipal solid waste, the research aiming on the determination of the influence of leachate recirculation on biogas generation was done. Experiments were done in two periods: just one month after bioreactor sealing with hydraulic loading rate (HLR) of 2 mm/d, and one year after bioreactor sealing with HLR of 3 mm/d. Doubling of biogas production from about 100 to 200 m³/h and the increase of methane content from 60 to 65% has been determined when 2 mm/d of HLR of leachate recirculation was applied. The implementation of HLR on the level 3 mm/d increased biogas production from 148 to 270 m³/d, and methane content from 62 to 64%. Leachate recirculation improved thermal conditions in bioreactor to typical meso-philic values.