Treatment of traces of oil from electroplating industry wastewater by using membrane bioreactor

Abstract

Membrane bioreactor (MBR) is a modification of an activated sludge process and is considered as a novel technology for treating wastewater. MBR process combines the activated sludge process with membrane filtration, which allows for a high effluent quality in terms of removal efficiency of oil and grease (O&G) and chemical oxygen demand (COD). In this study, performance of a laboratory-scale submerged hollow fibre membrane to treat oily wastewater from an electroplating plant in Johor was investigated. The degradation of raw oily wastewater at a hydraulic retention time (HRT) of 12.7 hours was studied. The experimental work was divided into three runs; the sludge retention time was one week prior to each run. Results of the three runs showed that O&G was biodegraded in the MBR treatment system with high extent, with removal efficiency between 91.1 to 98.7%. Results also showed a high removal efficiency of COD and BOD. The removal efficiency was 97.8% to 99.1% for COD and 77.8% to 86.1% for BOD. During the three runs membrane separation played an important role in providing a stable and excellent final effluent quality. The higher mixed liquor suspended solids (MLSS) concentration in Run 3 lead to higher biodegradability of O&G and COD in the biological tank, as a result the removal efficiency for this run was higher then for Runs 1 and 2, with a removal efficiency of 98.7% and 99.1% for O&G and COD respectively.