Performance Comparison of Conventional Method and Ultrafiltration in the Pretreatment of Landfill Leachate

After biological and/or physico-chemical treatment of landfill leachates (LFLs), chemical oxygen demand (COD) and total dissolved solids (TDS) content are often larger than reject requirements. In this case, reverse osmosis (RO) can effectively treat these residual COD and TDS. However, RO feasibility is limited by membrane fouling. LFL treatment of Oum Azza treatment is performed in two stages: a biological pretreatment, which consists of an aeration basin and an anoxic basin followed by a pocket filter, and in the second stage, the pretreated LFL is sent to RO unit. The monitoring of the performances of the plant shows a frequent stops for cleaning the fouling membranes due to the poor effluent quality after pretreatment. The pretreatment is the key of this operation, in terms of permeate fluxes and membranes lifetime. In this study, two pretreatment methods will be studied and compared: coagulation-flocculation by ferric chloride and aluminium sulfate and ultrafiltration (UF) membranes with different pore sizes (0.02, 0.05 and 0.1 μm). The performances of two pretreatment processes will be analyzed in terms of reduction of the major pollution indicators suspended solids (SS), COD and Biochemical oxyden demand (BOD5).