气浮-生化-超滤工艺处理低渗透油田回注污水

REINJECTION OILY WASTEWATER TREATMENT OF LOW PERMEABILITY OILFIELD BY GAS FLOTATION-BIOCONTACT OXIDATION-ULTRAFILTRATION PROCESS

为给污水站的建设提供合适的污水处理工艺单元和最佳参数,采用气浮-生物接触氧化-超滤组合工艺,以渤南低渗透油田回注污水为原水进行了现场中试试验。结果表明,当生化系统水力停留时间为8h时,气浮和生化处理可将污水中油的质量浓度降低到1mg·L-1以下,硫酸盐还原菌的数量控制在80个·mL-1以内,生化出水沉降后悬浮物的质量浓度稳定在20mg·L-1以内,粒径中值为0.7μm;超滤产水回收率在80%以上,透膜压差在0.04～0.06MPa;整套系统运行稳定,工艺出水悬浮物降低到0.6mg·L-1,粒径中值0.1μm,腐生菌为95个·mL-1,含油量和其它有害菌体未检出,达到SY5329—94规定的A1注水水质标准。

Low permeability oilfield requires the high quality injection water because of the small pore throat radius. Aim to provide a suitable technology unit ofwastewater treatment and the optimum parameters for the construction of sewage station, a pilot plant examination was carried out for the treatment of reinjection water from Bonan low permeability oilfield by using gas flotation-biocontact oxidation-ultrafiltration process.The results demonstrated that the average oil content was below 1.0mg·L^-1 by the treatment of floatation and biocontact oxidation when the hydraulic retention time （HRT）was 8 h, and the number of the sulfated-reducing bacteria was below 80 cells·mL^-1, the content of suspended solid could be lower than 20 mg·L^-1 by the treatment ofbiocontact oxidation and sedimentation, the median grain diameter was 0.7μm. Although the application of chemical cleaning was not conducted, the operation was still stable with the recovery rate of 80% above and the transmembrance pressure （TMP） between 0.04 and 0.06 MPa. The ultrafiltration could purify the water to 0.6 mg·L^-1 suspended solid content at 0.1μm median grain diameter, and 95 cells·mL^-1 TGB, the oil content and other malignant bacterias reached to undetectable levels in process effluent, which is satisfied with the A1 level of recommended injection water quality for clastic rock oil reservoirs and analyzing methods （SY/T 5329-1994）.