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为使3次采油废水的COD_(Cr)达到国家标准要求,在保留油田现有工艺处理的基础上,采用电凝聚-超滤耦合技术并投加无机混凝剂对3次采油废水进行深度处理。调整跨膜压差、反应时间、混凝剂投加量、电流密度、温度、pH值等进行条件筛选试验。电凝聚反应结束后启动超滤系统,从反应槽中取适量处理水,采用重铬酸钾法测定其COD_(Cr)。采用钢作电极,当极板间距为2 cm,pH值为7.00,硫酸铝混凝剂投加量为 300 mg/L,搅拌速度为500 r/min,电流密度为12.5 A/m~2时,40℃下水浴加热反应30 min后,启动超滤系统并控制跨膜压差为0.08 MPa,此时COD_(Cr)去除率达69.3%,出水COD_(Cr)值为81.8 mg/L,满足国家《污水综合排放标准》(GB 8987-1996)中一级标准要求。研究表明,混凝-电凝聚-超滤技术能够有效处理3次采油废水,反应时间为30-40 min,混凝剂投加量为300-400 mg/L,电流密度为12.5-16.7 A/m~2,温度为40℃,pH值为7-7.5时,其处理效果显著。
In order to make the COD_ (Cr) of the third oil recovery wastewater meet the requirements of the national standard, the tertiary treatment wastewater was treated with electro coagulation-ultrafiltration coupling technology and adding inorganic coagulant on the basis of retaining the existing process of the oilfield. . Adjust the transmembrane pressure, reaction time, coagulant dosage, current density, temperature, pH and other conditions screening test. After the electrocoagulation reaction was started, the ultrafiltration system was started. The appropriate amount of treated water was taken from the reaction tank and the COD Cr was measured by potassium dichromate method. A steel electrode was used. When the distance between plates was 2 cm, the pH was 7.00, the dosage of aluminum sulfate coagulant was 300 mg / L, the stirring speed was 500 r / min and the current density was 12.5 A / m ~ 2 After the reaction was heated in water bath at 40 ℃ for 30 min, the ultrafiltration system was started and the pressure drop across the membrane was controlled at 0.08 MPa. At this time, the removal rate of COD Cr was 69.3% and the effluent COD Cr was 81.8 mg / L, National “Integrated Wastewater Discharge Standard” (GB 8987-1996) a standard requirements. The results show that the coagulation-electrocoagulation-ultrafiltration technology can effectively treat the third wastewater, the reaction time is 30-40 min, the coagulant dosage is 300-400 mg / L, the current density is 12.5-16.7 A / m ~ 2, temperature 40 ℃, pH value 7-7.5, the treatment effect is remarkable.