“…14 Only wastewater with low oil content can be removed, it is easy to be blocked, and the cost is high; the biological treatment of oily wastewater has a long residence time and a large area, and the treatment effect on high-concentration oily wastewater is not ideal. 15,16 Ultrasonic wave is a new treatment method of demul-sication and degreasing; however, the technology is not sufficiently developed, the treatment effect on high-concentration emulsied oil wastewater is not ideal, it has not been widely used, and its processing cost is high. 17 As an efficient chemical pretreatment method, the coagulation method can effectively remove slicks, emulsied oils, suspended solids, COD, and turbidity in oily wastewater.…”