Fouling of reverse osmosis membrane applied to membrane bioreactor effluent treating landfill leachate treatment under various pH conditions

摘要

This research investigates the fouling behavior of reverse osmosis (RO) membranes in an integrated membrane bioreactor (MBR)-RO system for landfill leachate treatment. In a long-term operation under natural alkaline condition (pH 8.0-8.5), a full-scale integrated MBR-RO system achieved high treatment efficiencies (95%) but suffered RO membrane fouling as a result of calcium scaling. Specifically, in the study, the mixed liquor pH in MBR was varied between 5.5, 6.5, 7.5, and 8.5, and the effect on RO membrane fouling examined in laboratory-scale experiments. The results showed that pH influenced the removal of dissolved organic matters in the MBR and the characteristics of MBR permeates. At pH 5.5, the deposition of protein-like substances substantially reduced the RO flux, and calcium scaling on the RO membrane was clearly visible under pH 8.5. The RO flux slightly decreased under pH 6.5 and 7.5. The optimal pH for treating landfill leachate using the integrated MBR-RO system was between 6.5 and 7.5.