Membrane fouling mitigation techniques for oily wastewater: A short review

Oily wastewater is the largest liquid waste generated, mainly resulting from oil and gas production. It consists of hazardous materials, salts, toxic chemicals, surfactants and crude oil content. Therefore, it is considered a huge threat for the environment and marine life, and hence needs to be adequately treated before discharge into the sea. Among all technologies used for oily wastewater treatment, membrane technology has been found to be effective in handling emulsified oil droplets with a particle size of less than 40 μm. However, one of the major obstacles associated with the membrane technology is the deposition of foulants onto the membrane surface, a phenomenon referred to as membrane fouling, which severely reduces the treatment efficiency. Oily wastewater is an aggressive environment; hence membrane fouling could hugely and adversely impact the membrane performance. Recently, membrane fouling mitigation has been a main focus for researchers working in the area. In this review, various membrane fouling mitigation techniques in the treatment of oily wastewater were assessed. Membrane oscillation and pore structure, for example, play an important role in membrane fouling mitigation and have not been reviewed in the literature. The present study is mainly focused on the latest published literature in the field of fouling mitigation techniques for oily wastewater. It was found that membrane surface modification, chemical cleaning, membrane oscillation, pore structure, back flushing, and ultrasound are among the most common methods used for fouling mitigation. Therefore, these technologies were studied in detail and their limitations were reflected upon. Finally, the current status of these technologies was studied, and future trends were drawn out.