Brief Study On A/O Polluted Water Treatment Of Oil Recovery

Polluted water (PW) is the largest wastewater stream produced in oil and gas exploration process. Due to its serious environmental polluting, many countries have implemented very stringent control-standards for its discharge. Meanwhile, oil and gas industry all over the world is motivated to explore efficient and economical polluted water treatment technology.This thesis is focused on treatment of wastewater in oil production. Since ordinary polluted water contains diluted oil, current equipments are preserved as far as possible according to analysis of current treatment system. And new facilities are added to decompose further organic matter in the polluted water. Wastewater contains thick oil, therefore, more efficient chemical drugs are developed in order to remove suspended substances (SS) such as oil. A new system for wastewater treatment is thus developed by using technology for decreasing COD. Consequently, all components of baneful substance have been controlled under the standard of environmental protection of our country.In order to remove oil and SS from viscous crude water, a series of investigation are involved, such as, demulsification dose TJ-1 and flocculation chemical P-3. Different quantities of chemical medicine will be added according to the variation of oil concentration, the characteristics of wastewater. A suitable dose can reduce oil in water to 10mg/L, and provide important conditions to improve filtration and biology process.On the other hand, the ratio of BOD₅ / COD is over 0.2 so that it is difficult to treat. The key problem is to make produced wastewater reach the DischargeStandard by biological technology.Based on the analysis of wastewater treatment process of our country and abroad, a series of investigation can be carried on, such as, choosing bacteria that can break down organic compounds, cultivating active sludge, determining the main process factors like pH(7.3), temperature (298K³03K),treatment period (anaerobic treatment: 12h, aerobic treatment: 8h). The laboratory experiment results indicate that A/O combined method is feasible to decrease CODcr of the polluted water. By employing above biological methods to high concentration of COD& wastewater, the final rate of removing CODcr and oil is 77% and 84% respectively, the average concentrating of CODo in output water is lOlmg/L, and average concentration of oil in output water is 5.9mg/L. Water quality after this treatment is in line with the requirements of the Standard of Comprehensive Discharge for Polluted Water(GB8978—1996).The biology research has provided experiment basics for application in the oil production. The further pilot plant will be established, and combining different process like A/O, A/O , A /O to obtain optimized operative condition.