Test Study And Performance Analysis Of The No.3 Wastewater Treatment Plant Of Refinery Division In Gaoqiao Petrochemical Company

The No.3 wastewater treatment plant of refinery division in Gaoqiao Petrochemical Company was designed for treating the wastewater from domestic low sulfur crude oil processing, which treatment technique is a traditional three stage processes, that is oil separation, air flotation and biological oxidation. In recent years, due to the diversification of crude oil sources, the oil processing wastewater constitutent has changed greatly. The traditional oil separation, air flotation and biological oxidation process was unable to ensure the final effluent quality stability lower than the discharge standard. Therefore, the operation perfromance of the No.3 wastewater treatment plant of refinery division in Sinopec Shanghai Gaoqiao Branch Company was firstly evaluated through statistical analysis. Then, several main wastewaters’biodegradability was investigated through laboratory testing. Final, the possibility of Fenton reagent oxidation process used to treat the secoundary effluent was studied, and the condations of Fenton oxidation process were optimized.The results showed that oil concentration in the effluent of oil separation unit was about 30 mg/L, and the oil removal efficicency is about 85%-90%. Then, the oil content reduced to about 10 mg/L through air flotation. The total oil removal efficeny of oil separation and air flotation process was over 95%. Through the pretreteatemt, oil effect on biological process can decreased to minimum. Several main influents such as the oil cut water from tanks area, the drain of electro-desalting systems, and the drain of water purification system contain some refractory organics, which was main reason for the effluent CODCr-values exceeded the discharged standard. It is possible that the secondary effluent CODCr value decreased to less than 100 mg/L through Fenton oxidation process. The optimal condation for Fenton oxidation procsess were as following:initial pH level was 3.5; H2O2 and FeSO4·7H2O2 doseages were 1-2 mmol and 0.2-0.3 mmol, respectively; reaction time is 2 hours.