Biological Treatment of Vegetable Oil Wastewater in a Submerged Membrane Bioreactor

Vegetable oil wastewaters (VOWs) are generally characterized by offensive smell, dark color, and high organic content, including large amounts of oil and grease (O&G), fatty acids, phenolic chemicals, pectins, and lipids. Therefore, VOWs should be treated efficiency to avoid the environment pollution. The membrane bioreactor (MBR) is an alternative solution for VOWs treatment. In this study the organic pollutant removal performance, membrane fouling and the mixed liquor characteristics of a MBR for the treatment of real VOW was considered. During the 30 days operation of the MBR at hydraulic retention time and solid retention time of 48 h and 20 days respectively, there was a consistently low turbidity (<2 NTU) in the MBR effluent. MBR achieved COD and O&G removal from the wastewater of 85.0±1.3 % and 52.5%±2.6 % respectively. With decrease in MLSS and MLVSS concentration during the MBR operation, aerobic metabolic activity of the activated sludge decreased and COD and O&G accumulation occurred inside the bioreactor. The effluent COD value and the transmembrane pressure during the operation of the MBR remained in the range 88.7±11.5 mg L-1 and 0.1-1.0 kPa, respectively. The results of the present study indicate the very good potential of the MBR, both in terms of removal performance and membrane fouling, for treatment of VOWs.

Keywords:

Membrane Bioreactor , Vegetable Oil Wastewater , Biological treatment , Organic pollutant removal , Membrane fouling