Treatment of contaminated landfill leachate using aged refuse biofilter medium

Abstract

In this study, landfill leachate was treated in a biofilter filled with a mixture of aged refuse and gravel in the modified aged refuse (AR) biofilter column from square to cylindrical column by spraying the leachate over the surface of refuse in biofilter. The modified AR biofilter was evaluated for its performance in the treatment of landfill leachate from young waste cell of landfill (young leachate) and equalization lagoon (intermediate leachate) from sanitary landfill site. The hydraulic loading of 55 L/m3/d with 0.7 L.day-1 total leachate volume was sprayed over the refuse samples 2 times a day.The physical, chemical, and biological characteristics of AR were analyzed for evaluating the AR biofilter as leachate treatment host. The initial concentration of chemical oxygen demand (COD) and biochemical oxygen demand (BOD) for young and intermediate leachate is 4,800 mg/L, 1,260 mg/L and 6,400 mg/L, 1,125 mg/L respectively. After first cycle of treatment, the final effluent of young and intermediate leachate was inodorous and colorless with COD and BOD 800 mg/L, 60 mg/L and 1,600 mg/L, 120 mg/L respectively. The percentage of reduction is about 75%- 95%. The result relieved that over 85% of zinc, 96% if iron (Fe), 89% of cadmium, 82% of lead and 91% of copper were removed for intermediate leachate where as 38% of Zn, 85% of Fe, 65% of Cd, 30% of Pb and 59% of Cu were removed for young leachate by first cycle of single stage AR biofilter when the initial concentration of heavy metals were 6.5493 mg/L (Zn), 79.0209 mg/L (Fe), 0.314 mg/L (Cd), 1.2114 mg/L (Pb), 0.368 mg/L (Cu) and 3.442 mg/L (Zn), 18.945 mg/L (Fe), 0.105 mg/L (Cd), 0.139 mg/L (Pb), 0.088 mg/L (Cu) respectively.