Use of an Aged-Refuse Biofilter for the Treatment of Feedlot Wastewaters

Abstract

Refuse in the landfills and dumping sites becomes stabilized or aged over time. The aged refuse contains a wide spectrum and large quantity of micro-organisms, which can effectively decompose refractory organic matter present in some wastewaters, such as MSW landfill leachate. In this study, a biofiltration reactor consisted of the aged refuse excavated from a 10-year-old closed landfill compartment in the Shanghai Refuse Landfill (SRL) was used for biofiltration of livestock and poultry waste water sampled from a farm. Two hundred kilograms of screened aged refuse (diameter less than 15 mm) was used as biofiltration material in a cylindrical biofilter with a 40-cm inner diameter and a 150-cm height. Around 50 L/day (at a hydraulic load of 250 L/m³ refuse/day) of the preliminary-treated influent livestock wastewaters with initial COD_Cr, BOD₅, NH₃-N, total phosphorus concentrations of 197-2,419, 102-459, 260-1,140, and 24-102 mg/L, was intermittently sprayed over the refuse surface once a day with 3 h per interval. The pollutant concentrations were reduced to below 185 mg/L COD_Cr, 15 mg/L BOD₅, 27 mg/L NH₃-N, and 0.5 mg/L total phosphorus, with a removal of 64, 54, 75, 88, 94, and 99%, respectively. However, the removal of the total N is quite low, only around 20-30%. The NH₃-N is mainly converted to nitrate N. The removal of the total P is high, possibly because of the strong chemical absorption capacity of the aged refuse in the biofiltration reactor used. The effluent looks clear, in contrast to the brownish color of the influent. The treatment process developed is cost-effective and easily operated.