OIL/WATER SEPARATION TECHNIQUES USING HYDROPHOBIZED/OLEOPHILIZED GRAINS: A REVIEW OF RECENT STUDIES
Keywords:Oily wastewater, , Oil/water separation, Hydrophobized/oleophilized grains,, Adsorption, Filtration
Many domestic sources and industries, such as foods, textiles, metal industries, petrochemicals, and mining, produce massive volumes of oily wastewater all over the world. The insufficient treatment of oily wastewater in developing countries leads to serious environmental pollution and so on. In this review, we summarize many oil/water separation techniques to treat oily wastewater that have been developed such as flotation, chemical coagulation, biological treatment, filtration and membrane separation, and adsorption. Among them, oil/water separation techniques based on adsorption and filtration utilizing naturally hydrophilic sands and hydrophobized/oleophilized grains are worth attention due to their ease of application and cost effectiveness. In this review, we summarize recent studies on adsorption- and filtration-based oil/water separation techniques utilizing naturally hydrophilic sands and grains coated/modified with hydrophobic/oleophilic substances and compare the treatment performance, categorizing types of grains, coating substances, oil used, and testing methods. Prospects and challenges of oil/water separation studies are also given.