Assessment of in-situ aerobic treatment of municipal landfill leachate at laboratory scale

One of the most important issues of concern in landfill management is the treatment and management of leachate. In situ aerobic treatment of landfill leachate using leachate recirculation was investigated in this research at laboratory scale. A plastic container with dimensions of 0.5 x 0.5 x 1.0 m was used as a reactor. Two sets of aeration pipes were placed inside the reactor and connected to an air compressor in order to inject air into the waste mass.  Leachate was collected in a container at the bottom and pumped to another container at the top, from which leachate was recirculated back into the waste mass. The output of the screen unit of Isfahan composting plant was used as waste material. The composition of the waste was modified by adding crushed glass and shredded paper, plastic and metal containers to obtain the same composition of the collected waste. Twenty eight liters of leachate was recirculated daily for 75 days. Samples of the leachate were collected and analyzed for COD, TDS, TSS, pH, heavy metals and temperature. Total COD removal efficiency of the system was 91%. Temperature increased initially and reached a maximum of 53 °C due to rapid biodegradation of the organic matter. As the biodegradation slowed down, less heat was generated and as a result the temperature inside the reactor dropped. Both TDS and TSS showed an initial rise due to recirculation of leachate. Then, biodegradation of organic matter over time resulted in a decrease in both TDS and TSS. The removal efficiencies of the system for TDS and TSS were 56% and 34%, respectively. Removal efficiencies of 93%, 90%, 43% and 76% for Mn, Fe, Pb and Zn were respectively observed