Development of New Filter Membranes for Separating Oil from Wastewater and Design of a New Oil-Water Separation Process

Abstract The objectives of this work are to invent new ceramic membranes which are effective in separating oil from wastewater, especially in separating emulsified oil-water mixtures, and to propose an oil-water separation process. With the new filter membranes and the separation process, a separation facility can achieve long term operations with low maintenance and high separation efficiency. The superior separation result of the filter membranes is achieved by coating the membranes with super hydrophilic and super oleophobic nano materials. The filter membranes are effective in separating oil from wastewater, especially in separating emulsified oil-water mixtures. They are designed at different pore sizes depending on separation requirements. The proposed new separation process combines several common separation methods such as IGF, filter membrane, etc., as well as a backwash process. The filter membranes and the oil-water separation process were tested on produced water reinjection in oil fields, on wastewater discharge from drilling, and wastewater containing oil and suspended solids from a petrochemical plant, as well as other samples. Treating produced water for reinjection in an oil field shows that the effluent oil contents were reduced to around 2 ppm from the influent oil contents of 21-23 ppm, and the effluent suspended solids were reduced to below 1 ppm from the influent suspended solids of 15-19 ppm. Results of treating quench water at a petrochemical plant show that both the effluent oil contents and suspended solids were reduced to less than 10 ppm while the influent oil contents were around 8%. The new filter membranes combined with the new oil-water separation process improves separation efficiency, requires less backwash, as well as achieves safe, stable, long term operations with low maintenance. The new separation process is also simple, smaller in size, and more energy efficient. It can be used in wastewater treatment in petroleum exploration and production, oil refineries, petrochemical, and other industries.