Combining anerobic degradation and chemical precipitation for the treatment of high strength, strong nitrogenous landfill leachate

Abstract

Treatment of organics and ammonium from sanitary landfill leachate was investigated using a combination of anaerobic treatment and magnesium ammonium phosphate precipitation (MAP) processes. The effect of organic loading rate (OLR) was evaluated for the removal of COD and BOD(5) in an anaerobic treatment by anaerobic sludge blanket (UASB) reactor. The UASB reactor removed organics successfully. OLR has a significant effect on the reactor performance and the maximum COD removal was 90% at an OLR of 9 kg COD/(m(3)d). On average, 86.3% of COD and 95.3% of BOD(5) were removed at a steady state of anaerobic treatment. MAP precipitation was performed in order to decrease the ammonium concentration of anaerobically-treated leachate. Furthermore, the effect of pH and the molar ratio of MAP constituents on the removal of ammonium were evaluated. The maximum ammonium removal was observed as 98% at a pH of 8.5 and a stoichometric ratio of NH(4)/PO(4)/Mg = 1/1/1. The results obtained indicate that a combination of UASB and MAP can be successfully used for the removal of organics and ammonium from sanitary landfill leachate.