Research On Ultrafiltration Menbrane For Treating Micro-polluted Raw Water

With the improvement of living qualities and development of society, people's requirements to the quality of drinking water are increasingly stringent, and the national drinking water regulations are also enhanced. At the same time, water resource contamination is getting serious more and more. Nowadays, traditional water treatment processes have been nearly unable to meet the requirements of drinking water quality. Ultrafiltration (UF) drinking water treatment technologies is good at guaranteeing water quality and safety, thereby it is becoming one of key points researched in the current water treatment field.The subject is a pilot study on UF process directly deals with micro-polluted raw water; and powder activated carbon (PAC) /UF process deals with micro-polluted raw water; and micro-flocculation/UF process deals with micro-polluted water. The main conclusions of the study are as follows: 1, Turbidity removal rate of direct UF is greater than 99.0%, effluent turbidity can achieve no more than 0.1 NTU, which completely satisfies the new "National Life Drinking Water Health Standards" (GB5749-2006). COD_Mn removal rate is about 25.8% to 46.9%, effluent COD_Mn is lower than 2.5mg/L, under test conditions. UV₂₅₄ removal rate is about 13.3%. Ultrafiltration transmembrane pressure (TMP) growth rate has good linear relationship with filtration operation time. The surface air supported water rinse can significantly reduce the overall growth rate of TMP, and membrane cleaning performance improvement is marked. 2, When the PAC concentration of 80 mg/L, PAC/UF process on COD_Mn and UV₂₅₄ removal were respectively about 64.5 % and 61.8 %. Dosing PAC into UF system will not only don't cause TMP rise, but also can slow down the membrane fouling, and TMP dropout rate is in inversely proportional to PAC concentration. 3, Micro-flocculation/ultrafiltration process can effectively improve organic pollutants removal, and reduce membrane fouling. When the coagulant dosage was of 10 mg/L, COD_Mn and UV₂₅₄ removal rate was respectively 53.4% and 36.3%. With the same dosage, using polyaluminium chloride as coagulant has a more effective organic matter removal than using ferric chloride, especially for dissolved natural organic matter. Adding flocculant PAM into micro-coagulation/UF system can slow the membrane fouling in a certain role. Membrane fouling is lightest when PAM dosage is of 0.06 mg/L.