Effect of mineral oil on in situ treatment of sewage at riverside discharging point by enhanced biofilm process with enzyme

The research studied enhanced treatment of sewage from discharging points of rivers by biofilm process dosing with enzyme and the effect of mineral oil on removal rates of the main pollution indexes, and investigated promotion effect of enzyme (including the laboratory developed compounded enzyme and the foreign composite enzyme) on treatment of sewage by biofilm process. The research results indicated that when mineral oil with the concentration of 25 mg/L was added to reactor A, B and C, respectively, the removal rates of mineral oil, COD_Cr and ammonia nitrogen all obviously decreased. Meanwhile, the removal rates of mineral oil, COD_Cr and ammonia nitrogen were higher in reactor B and C than in reactor A, and the removal rates of them in reactor B were similar to them in reactor C, which indicated that enzyme had good promotion effect on biofilm process during the sewage treatment process.