Treatment of leachate by aged-refuse-based biofilter

Abstract: Refuse in landfills becomes stabilized or aged, as organic matter in the refuse gradually degrades and as the soluble inorganic substances dissolve during its long-term stabilization process. Within this paper, this process is referred to as mineralization process and the resultant stabilized or essentially stabilized refuse is referred as “aged refuse”. The aged refuse contains a wide spectrum and large quantity of microorganisms, which have a strong decomposition capability for refractory organic matter present in some wastewaters, such as leachate. In this study, aged refuse excavated from 2 to 10 year old closed landfill compartments in Shanghai Refuse Landfill (SRL) was characterized in terms of particulate distribution by screening, and a biofilter consisting of 10 year old aged refuse was then used for biofiltration of leachate sampled from the landfill. Typically, 400 kg of screened aged refuse with limiting diameter less than 15 mm was used as biofiltration materials in a round shape biofilter with 80 cm of inner diameter and 80 cm of height. Leachate with initial COD, BOD, and NH3-N concentrations of 3000-7000 mg/L, 540-1500 mg/L, and 500-800 mg/L, respectively, was passed through the biofilter. As a result, the corresponding concentrations in effluent are reduced to lower than 100-350 mg/L, 10-200 mg/L, 10-25 mg/L, respectively, 90-99 % removal for these parameters at a hydraulic load of 80-20