| This paper presented the results of investigation concerning the formation, structure and separation properties of fiber membranes made of polyvinylidine fluoride (PVDF) and polyvinyl chloride (PVC). The miscibility of the polymer blends PVDF and PVC was discussed. Furthermore, effect of dope composition, composition of coagulation bath and spinning conditions on structures and properties of PVDF/PVC hollow fiber membranes was also investigated. The stability and fouling resistance of PVDF/PVC hollow fiber membranes were discussed. At last, the PVDF/PVC membranes were used in the treatment of the kenaf fibers microbial retting wastewater and the effluent from sedimentary tank of municipal wastewater treatment plant. The porosity of the PVDF/PVC membranes was determined by SEM observations and porosity, and the separating properties of membranes were determined by measuring the water flux and retention coefficient of BSA solution or average pore size.The miscibility of the polymer blends of PVDF and PVC was discussed through thermodynamics, the method of solution, the solution viscosity, and the measure of the optics transparency respectively. The results showed that the polymer blends PVDF and PVC are partial miscibility. While one component largely exists, a homogeneously casting solution can be obtained. And the miscibility is excellent when the blend ratio of PVDF and PVC is 7/3. The effects of the blend ratio, solid concentration, solvent, additive, bore fluid concentration, dry-journey on the structure and performance of PVDF/PVC alloy hollow fiber membranes were discussed. The results showed that the hollow fiber membranes can be obtained when the ratio of PVDF and PVC is 7/3, the solid concentration is 18%, the solvent is DMAC, the additive is PVP, whose water flux is 430L.m-2h-1 and average pore size is 0.29μm.And when the solution is NMP, the membranes' capability is more excellent. The membranes from micro filtration to ultra filtration can be obtained when the solution contains different ratio of DMAC and NMP. The concentration and temperature of the coagulation bath and spinning conditions all have a great effect on structures and properties of PVDF/PVC hollow fiber membranes. Compared with the temperature of the coagulation bath, the concentration of the coagulation bath has more effect on the PVDF/PVC membranes. Increasing the concentration of the coagulation bath will make the membranes structure change from unsymmetrical structure to symmetrical structure. When the temperature of the coagulation bath is 15 ~ 40 ℃ , the concentration of the solvent in coagulation bath is 0~40%, and the concentration of the solvent in bore fluid is 40~70%, the membranes with excellent performance can be obtained. Adjusting the three parameters can control the membranes' structure and pore size. When the dry-journey varies from 2~15cm, the water flux of the membranes varies little, but the pore size decreases, so the appropriate dry-journey is 6~10cm. Chemical stability of the PVDF/PVC membranes was tested through the method of immerging them in acid, alkaline and oxidative reagent, the results showed the blend membranes have good acid resistance, and have inferior alkali resistance and oxidation resistance.The post treatment of immerging PVDF/PVC blended membranes in sodium hypochlorite solution has great effect on the membranes' capability and structure. The pure-water fluxes of membranes increased significantly and the structure of the membranes varied greatly when immerging the membranes in 3000~5000mg/L sodium hypochlorite solution for 36-48 hours. The membrane fouling resistance was tested through filtering the bovine serum albumin (BSA) solution. The experimental results showed that the PVDF/PVC blended membranes have a low fouling resistance. It was suggested that the membrane should to be have a surface modification or other post treatment methods to improve its surface hydrophilicity.Finally, the PVDF/PVC hollow fiber membranes were made into membrane modules. The biological reactor was used to treat the kena...
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