UASB-MSBR-Fenton/Coagulation Process For Treatment Of Oil Wastewater

China oil industry is developing rapidly, and it has become one of the world’s biggest grease consumer. As oil production wastewater contains high organic concentration and a amount of grease, without strict treatment, direct discharge will cause considerable pollution of water and soil environment. It has important practical significance and broad application prospects of oil wastewater biodegradation. This experiment take Hunan Xiangtan oil production wastewater as the research object, using the UASB-MSBR-Fenton/enhanced coagulation process for the experimental study of water samples, test results show that:(1) UASB reactor using mature particle sludge as inoculation sludge, in medium temperature(35 ± 2℃), acclimation of activated sludge treatment of oil containing wastewater. The study showed that, treatment of oil wastewater in the domestication of anaerobic granular sludge, stable operation of the reactor, the COD is 3800-4250mg/L, the pH is 6.9-7.2, the retention is 2d, the removal rate reached 87%, the effluent COD is 480-520mg/L.(2) Aerobic activated sludge adaptation UASB reaction after the water, the volume of container reactor was 2L, influent 1L, reactor volume exchange ratio is 1:2, operating conditions for instantaneous water, stirring 1h, anoxic aerobic aeration 4h, precipitation time 1h and instantaneous drainage. Under this condition, the removal rate of ammonia nitrogen and total phosphorus were 87.7% and 96.1%, reached the standard of integrated wastewater discharge standard (GB8978-1996). Contact oxidation effluent color 100 times, COD at about 200mg/L, the removal rate reached 59.6%, does not meet the integrated wastewater discharge standard (GB8978-1996) standard, need further treatment.(3) Fenton/enhanced coagulation test. Fenton reagent oxidation treatment, anaerobic effluent, start with H2O2 dosing quantity, FeSO4·7 H2O dosing quantity, initial pH, reaction time as the impact factor of orthogonal experiment design, Fenton oxidation initial operating conditions were determined, and single factor optimization experiment, Fenton oxidation optimal processing conditions were determined as:pH =4.5, H2O2 dosing quantity is 0.75L/m3, FeSO4·7 H2O dosing quantity is 0.5Kg/m3, the reaction time of 120 min. Under the optimal combination of conditions, COD removal rate can reach 67%, the chroma is reduced to 45 times. Fenton after completion of the reaction, the supernatant were enhanced coagulation experiment, by adjusting the pH value to 8, the addition of PAM to the amount of 3mg/L, Fenton can improve the treatment effect, followed by enhanced coagulation, reduce the effluent COD to 41mg/L and the chroma was reduced to 30 times. The effluent can reach the standard of integrated wastewater discharge standard (GB8978-1996).(4) The actual operation of the project showed that, after pretreatment oil and suspended solids removal rate was 92%; the UASB/MSBR/Fenton/coagulation process for treatment of oil wastewater, regulating water quality pH after the treatment of oil wastewater anaerobic sludge acclimated to start UASB, time 60d, the removal rate of COD degradation in about 88%, reflux time of day ensure 6h; aerobic MSBR further treatment of organic compounds, the removal rate of around 65%, aeration time every day to ensure that the 5h. The effluent of MSBR Fenton reaction COD 200mg/L, chroma 100 times, the reaction time is 120min, hydrogen peroxide dosage 0.6L/m3, ferrous sulfate dosage is 0.7Kg/m3, the initial reaction under the condition of pH 4.5, COD and color removal rate were 70%,66.7%. With the treatment of UASB/MSBR/Fenton/coagulation process for oil, all the effluent indexes meet the first classcriteria specified in the Integrated Wastewater Discharge Standard (GB8978 -1996),per ton of wastewater treatment costs about 3.75 yuan.