Effects on landfill methane production by different leachate recirculation operations

At present, comprehensive and successful study on leachate recirculation technique to degrade the organic pollutants in the fresh MSW landfill in developing country, which characterized of food waste being the main biodegradable component, is lack. In this paper, lab-scale landfill columns that simulated the fresh MSW landfill based on the MSW composition in China, effects on methane production by different leachate recirculation operations were studied. During the experimental course, leachate without any pretreatment, leachate pretreated by aerobic process (SBR) or mixed with leachate from mineralized landfill was recirculated to landfill columns respectively. The results indicate that COD and VFA concentration in leachate at the initial stages was higher. Such leachate recirculating to landfill columns directly or without any pretreatment would lead to accumulation of the volatile fatty acid (VFA) and to inhibition of methane fermentation. When leachate was pretreated to some extent then recirculating to landfill columns would greatly shorten the methane production lag phase time and speedup the methane fermentation. Only when methane fermentation is created and maintained steadily, the landfill organic pollutant can be biodegraded effectively, and nearly 100 percent of the organic pollutant is conversed to landfill gas.