Study on coagulation treatment and floc settling rate of alcohol and oil containing wastewater

Abstract Methanol, as a new type of energy, is becoming increasingly widely used in society. However, how to efficiently utilize and recover methanol has become a major challenge. In order to improve the methanol recovery efficiency of the methanol distillation tower, this paper applied the chemical oxidation coagulation method to pretreat the high alcohol and oil containing wastewater entering the methanol distillation tower. The results showed that the transmittance of the supernatant of the treated water could reach 97.76%, and the removal rates of suspended solids, oil, and iron were 99.71%, 98.62%, and 98.61%, respectively. This can meet the inlet water index of the methanol distillation tower in Yanchang Oilfield Gas Production Plant 2, indirectly improving the methanol recovery efficiency in the methanol distillation tower. By examining the settling velocity of flocs, it was found that the maximum settling velocity of flocs was 0.848mm/s when the methanol content was 40%. The settling velocity of flocs decreased with the increase of the ratio of condensate oil/suspended solids content. When the ratio of condensate oil/suspended solids content was greater than 5.88, flocs would float up and the optimal coagulation formula would no longer be applicable.