Treatment of Synthetic Pesticide Industrial Wastewater with Nanofiltration and Photo-Fenton Oxidation Using Malathion as a Model Substrate

Nanofiltration (NF) and advanced oxidation process (AOP) using photo-Fenton's reagent were used independently to treat malathion as a model substrate in pesticide industry wastewater. Among the three types of NF membranes used (NF-A, NF90, and NF270), NF270 membrane has the largest water flux, but did not meet the desired effluent concentration of 0.1 mg/L. NF90 and NF-A membranes could reduce the malathion concentration to 0.06 mg/L, but provided a lower flux rate compared to NF270 membrane. The optimum initial ratios of chemicals in AOP experiments were malathion: H2O2 = 1:100 and H2O2: Fe(II) = 40:1. It took 1 hour, 2.25 hours and 3 hours to reduce the malathion from different initial concentrations to the desired level. The specific energy consumption was determined for each treatment scheme to evaluate the economic feasibility of NF-AOP combination. AOP is the significant energy consumer in the combined process and hence should be minimized by enhancing NF.