Pretreatment of municipal landfill leachate by a combined process

Biodegradability enhancement of landfill leachate using air stripping followed by coagulation/ultrafiltration (UF) processes was introduced. The air stripping process obtained a removal efficiency of 88.6% for ammonia nitrogen (NH4-N) at air-to-liquid ratio of 3500 (pH 11) for stripping 18 h. The single coagulation process increased BOD/COD ratio by 0.089 with the FeCl3 dosage of 570 mg l(-1) at pH 7.0, and the single UF process increased the BOD/COD ratio to 0.311 from 0.049. However, the combined process of coagulation/UF increased the BOD/COD ratio from 0.049 to 0.43, and the final biological oxygen demand (BOD), chemical oxygen demand (COD), NH4-N and colour of leachate were 1223.6 mg l(-1), 2845.5 mg l(-1), 145.1 mg l(-1) and 2056.8, respectively, when 3 kDa molecular weight cut-off (MWCO) membrane was used at the operating pressure 0.7 MPa. In ultrafiltration process, the average solution flux (J(V)), concentration multiple (M-C) and retention rate (R) for COD was 107.31 m(-2) h(-1), 6.3% and 84.2%, respectively. Crown Copyright (C) 2009 Published by Elsevier B.V, on behalf of The Institution of Chemical Engineers. All rights reserved.