Analysis of coagulation behavior of oily wastewater containing high methanol

In this paper, the chemical oxidation-coagulation method was used to treat oily wastewater containing high methanol and the influence factors of coagulation were studied. When pH value of wastewater was adjusted to 8.5, the dosage of H₂O₂, PAC and cationic polyacrylamide was 175 mg·l^-1, 40 mg·l^-1, 1.0 mg·l^-1 respectively, the quality parameters of coagulated water such as pH value, contents of oil and suspended solid (SS) could achieve the feed-in require of methanol rectifying tower. In coagulation test, the dependence of floc sedimentation velocity on methanol concentration and ratio of Oil/SS was studied, the results showed that the sedimentation velocity of floc decreased with increasing methanol concentration, and the velocity varied slowly and tended to keep stable when the methanol concentration was over 53.0%; While Oil/SS<;6, the sedimentation velocity of floc decreased with increasing Oil/SS. Once oil/SS>;6, the floc floated upward due to higher condensate-oil concentration.