Study On Treatment Technology Of Oily Wastewater Of Hongqian Block In Xinjiang Oil Field

Now oil fields generated huge amount of oily wastewater.Not only did these oily wastewater increase the cost of oil exploitation,but also make damage to the surrounding environment.The oily wastewater in this study gathered from Hongqian Block in Xinjiang Oil Field,with high oil,high COD and high SS.This paper developed a treatment process and designed a set of device to deal with it which made an important practical significance to the oily wastewater treatment.After treating,the wastewater could meet the reinjection standard and discharged standardWater quality experiment showed that the oily wastewater gathered from Hongqian Block in Xinjiang Oil Field belonged to typical CaCl₂ type,which had a high level of SS,COD and oil beyond the standard of reinjection and discharge.Laboratory tests were made with the method of Flocculation-Biochemical treatment-Charged membrane,PAC and PAM were used to accelerate the precipitation of Ca²⁺,Mg²⁺,scale-forming ions and flocculation.Besides,they could reduce the difficulty of subsequent treatment process.The best concentration were50mg/L and 2 mg/L.In order to meet the standard of discharge,RH bacteria was used to study the effect on COD and oil,pH was 7-8,inoculation was 20%,reaction time was 24-32 hours,RH bacteria could reach the optimum effect.Oil was reduced by 68.81%and COD was reduced by 66.75%.PTFE charged membrane was used to study the effects on oil and SS,oil was reduced to 1mg/L from 16-23mg/L,SS was reduced to 1-2mg/L from 100mg/L,The treated wastewater has good compatibility with formation water,Both Mg²⁺and Ca²⁺loss rate were less than 2%,which meant it could meet the reinjection standard.To design and manufacture a comprehensive treatment device,it mainly contained Aeration tank,Swirl flotation,Biochemical pool and Sedimentation tank.The waste water quality after treatment was as below:COD 70-100mg/L,oil 2-9mg/L,SS 10-20mg/L,all the index above could meet the standard of reinjection and discharged standard GB 8978-1996.