Study On Treatment Of Drilling Wastewater

Drilling wastewater is generated from crude oil exploitation and refinement process. Various wastewater discharge amounts, complex water quality, high salinity and other water quality indexes of drilling wastewater made it will cause great harm to environment if discharged directly. With the increasingly strict laws and regulations of our country, more and more complex exploitation way and deeper well drilling depth than ever before, the treatment of drilling wastewater has become more and more difficult, so exploration for economical reasonable and technically feasible treatment process is imperative.Experiments were carried out on the single process of oil separation, heating demulsification, chemical flocculation, aerobic treatment, Fenton oxidation to study and optimize their treatment effect on drilling wastewater, and then the combined process was studied and evaluated.Combined oil separation process "API-CPI-API" was used to treatment the wastewater and results showed that the average oil concentration removal efficiency was up to87.9%Removal efficiency of oil concentration and chromaticity of the heating demulsification process could be up to99%and80%, respectively.After the chemical flocculation process, oil concentration of effluent wastewater was below100mg/L, COD was about4000mg/L, and biodegradability was improved from0.15to0.5.After the aerobic treatment process, Oil, COD and chromaticity of the effluent wastewater were20mg/L,1800mg/L and90times respectively.During the Fenton oxidation process, optimization experiment showed that the dosage amount of H2O2and FeSO4·7H2O were8.2mL/L and13.69g/L respectively; the effect of Fenton process could be influenced on some extent by the dosage rate of H2O2:when its rate was at1mL/min the removal efficiency of COD was52%, about10%higher than that of added instantly.Effect of the combined process "oil separation-heating demulsification-chemical flocculation-aerobic treatment-Fenton oxidation" on the treatment of drilling wastewater was prominent. The water quality of the effluent had reached the secondary standard of DB12-356-2008of Tianjin. It was indicated that the process used was an effective method in the treatment of drilling wastewater.