Pilot study on the advanced treatment of landfill leachate using a combined coagulation, fenton oxidation and biological aerated filter process

Mature landfill leachate is typically non-biodegradable. A combination process was developed that includes coagulation, Fenton oxidation, and biological aerated filtering to treat biologically-produced effluent. In this process, coagulation and Fenton oxidation were applied in order to reduce chemical oxygen demand (COD) organic load, and enhance biodegradability. Poly-ferric sulfate (PFS) at 600 mg l−1 was found to be a suitable dosage for coagulation. For Fenton oxidation, an initial pH of 5, a total reaction time of 3 h, and an H2O2 dosage of 5.4 mmol l−1, with a (H2O2)/n(Fe2+) ratio of 1.2 and two-step dosing were selected to achieve optimal oxidation. Under these optimal coagulation and Fenton oxidation conditions, the COD removal ratios were found to be 66.67% and 56%, respectively. Following pretreatment with coagulation and Fenton oxidation, the landfill leachate was further treated using a biological aerated filter (BAF). Our results show that COD was reduced to 75 mg l−1, and the color was less than 10 degrees.