Influence Of Landfill Structure On Leachate Recirculation Effect In Pilot-scale Experiment

At present, sanitary landfill is the main disposal technology of municipal solid waste (MSW). As a mature and less expensive one, this technology is proper to developing countries well. Leachate is the principal environmental problem of landfill, which is high-density organic waste water produced by the decomposition of municipal garbage. The treatment of leachate is still a world-wide problem because of its complexity, worse biodegradability and fluctuation of water quality and quantity.Disposal is an important function of MSW landfill. With the increasing of air and moisture content in landfill through leachate recirculation, the contaminants in leachate degrade and the water quality improve by a series of physical, chemical and biological reaction. The landfill structure is changed to improve leachate quality using disposal function of MSW landfill.In this pilot-scale experiment, site is in Jiujiang landfill and material is Jiujiang MSW and landfill leachate. Two large-scale landfill installations (21 m×3.8 m×6.0 m) were built according to semi-aerobic landfilling and anaerobic landfilling theories. The concentrations of COD_Cr, BOD₅, NH₃-N and NO₃-N and pH were detected in influent and effluent of different structural landfill to study the leachate recirculation effect under different contaminated loading and hydraulic loading. The purpose is to work out cheap and high efficient landfill operation and management methods which adapts to our situation and could dispose leachate easily.The results showed that, two landfill structures have remarkable removal effects on BOD₅ and COD_Cr of leachate. Semi-aerobic landfill has good removal effect on NH3-N. In low organic loading, with the increase of hydraulic loading, the removal of COD_Cr drop gradually. When the hydraulic loading increase from 6.27 L/m²Â·d to 31.3 L/m²Â·d, the removal rate of COD_Cr in semi-aerobic landfill decline from 89.5% to 75.6%, and that in anerobic landfill from 88.4% to 67.1%. The best hydraulic loading is 18.8 L/m²Â·d on basis of recirculation effect contrast under different hydraulic loading.