| At present, most oi1fields in China have entered late oil exploitation, during which the large amount of oil-bearing wastewater was produced. However, the water quality standard of is difficult to be reached under traditional filter technology treatment. Deep treatment to the oil-bearing wastewater by membrane process is one of the key technologies for oi1field recycling water. The knotty problems for wide application of membrane process lie in the membrane fouling. Charged membranes are attracting increasing attentions for the resolution of membrane fouling. From the membrane screening study on PP, PVDF, PES and PTFE in this paper, it was found that the PVDF membranes were more suitable for the treatment of oil-bearing wastewater in oi1field. The charged PVDF porous membranes have been prepared by irradiation grafting with ultraviolet ray. By orthogonal experiments, the optimum preparation conditions for the charged membranes have been determined as follows: 15% of monomer concentration, 30 min of irradiation time and 6% of initiating agent concentration. By infra-red analysis and SEM analysis, the existence of grafting material on membranes has been confirmed. By orthogonal experiments, the effects of monomer concentration, irradiation time, initiating agent concentration and water temperature during experiments on fouling resistance performance of charged membranes have been investigated. The experiments results showed that optimum preparation conditions were 5% of monomer concentration, 20 min of irradiation time, 7% of initiating agent concentration and 60℃of water temperature. The comparison experiments for the separation performance and fouling resistance performance of charged PVDF porous membranes and PVDF porous base membranes have been conducted. The results showed that the charged membranes have better performance than porous base membranes. The separation performance and fouling resistance performance of charged membranes were also discussed by theoretical analysis. The practicability of prepared charged PVDF porous membranes in treatment of oil-bearing wastewater with low concentration was investigated. The results showed that the filtered water was limpid under the following source water conditions: oil content lower than 20 mg·L-1, median diameter of suspended matter lower than 8μm. The water quality of water outlet reached the A1 stage standard according to"Recommending Indexes for water Quallty of Water-Feeding in Clastic Rock"(SY5329—94).
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