Research On Improving Biodegradability Of Heavy Oil Processing Wastewater

Heavy oil refining wastewater is very difficult to treat because of its high pollution load, complicated components, serious emulsification, hard separation and low biodegradability. So 60m3/h pretreatment equipment was built to treat the heavy oil processing wastewater and recycle the oil resources in 2005. However, with the upgrade of oil product quality and the complication of oil processing technologies, the pollutant of tinpot oil wastewater has exceeded the original maximum treatment load. Therefore, many work for characterizing the heavy oil refining wastewater, evaluating of the wastewater pretreatment process, and researching on the biodegradability improving technology were done in this paper, in order to solve the problem and enhance the wastewater's biodegradability.The research result shows that there were a very high content of polar organic pollutants, sulfide and ammonia nitrogen in the heavy oil refining wastewater which were good for the formation of a stable O/W emulsion. Moreover, the main composition of organic pollutant of wastewater was organic acid, phenol, polycyclic aromatic hydrocarbons, heterocyclic oxygen molecules compounds, alcohols, esters, long chain alkanes, those pollutants were the reasons that restricted the biological degradation. The evaluation of pretreatment process shown that CODcr, oil and SS was effectively removed, but the effluent remains high biological toxic, hard degradation, and low B/C value0.16. Fenton oxidation can improve the biodegradability of wastewater, but difficult to industrial application for the corrosion and complex operation. Ozone oxidation can improve the biodegradability of wastewater more than 15% in 20 minutes, which is an optimal biodegradability improving technology for heavy oil refining wastewater.