矿井水处理聚合氯化铝残留物对超滤膜污染的影响

Influence of Polyaluminium Chloride Residue on Ultrafiltration Membrane Fouling in Mine Water Treatment

针对矿井水混凝处理过程中投加的聚合氯化铝(PAC)残留物对超滤膜的污堵问题,采用在聚偏氟乙烯(PVDF)超滤膜前投加不同量的PAC对矿井水进行混凝和超滤试验,考察PAC不同投加量下浊度、污染指数(SDI)、残留铝含量、跨膜压差(TMP)和归一化膜比通量(NSF)间的相互关系及对超滤膜的影响。结果表明:当PAC投加量为35~40 mg/L时,混凝上清液中SDI最小为5. 3,残留铝含量约为0. 16~0. 23 mg/L,浊度约为6. 0~8. 0 NTU。跨膜压差随着PAC投加量、残留铝含量和pH值的增加而上升。当PAC投加量为40 mg/L、残留铝含量为0. 18 mg/L、pH值为4. 2~5. 2时,跨膜压差(TMP)最小值约为64. 8~68. 4 kPa。水中残留铝存在形态在不同pH值条件下可相互转化,其聚合态和絮凝体粒径又影响着超滤膜污染,酸性条件(pH值为4. 2~5. 2)下更有助于减少残留铝对超滤膜的污染。

Aiming at fouling of the ultrafiltration membrane caused by polyaluminium chloride( PAC) residue added in the process of mine water coagulation treatment,different amounts of PAC were added in front of polyvinylidene fluoride( PVDF) ultrafiltration membrane to carry out coagulation and ultrafiltration tests to treat mine water,and the relationships among turbidity,SDI,residual aluminum content,transmembrane pressure( TMP),normalized membrane specific flux( NSF) and their effects on ultrafiltration membranes were investigated under different PAC dosages. When PAC dosage was 35-40 mg/L,the minimum SDI in the supernatant was 5. 3,the residual aluminum content was 0. 16-0. 23 mg/L,and the turbidity was 6. 0-8. 0 NTU. The TMP value increased with the increase of PAC dosage,residual aluminum content and pH value. When PAC dosage was 40 mg/L,the residual aluminum content was 0. 18 mg/L,the pH value was 4. 2-5. 2,the minimum TMP was 64. 8-68. 4 kPa. The morphology of residual aluminum in water could be converted to each other under different pH values,and the polymeric state and flocculent particle size also affected the membrane fouling. Therefore,acid condition( pH of 4. 2-5. 2) was more helpful to reduce the pollution of residual aluminum to ultrafiltration membrane.