炭砂过滤单元对超滤膜阻力的影响研究

Effect of Sand-carbon Filtration on Performance of Ultrafiltration Membrane in Drinking Water Production

为了研究炭砂过滤单元对浸没式超滤膜的影响,以北京市某给水厂的机械加速澄清池出水为研究对象,比较了"混凝沉淀/超滤"和"混凝沉淀/炭砂过滤/超滤"工艺中膜过滤单元的运行特性、膜阻力及出水水质。增加炭砂过滤单元后,跨膜压差(TMP)的上升速度得到缓解,增长率由1.23 k Pa/d下降为0.29 k Pa/d;对不同膜阻力分别进行测量并辅以扫描电镜和三维荧光技术表征膜面及出水水质,发现炭砂滤柱可以截留沉后水中的矾花,使膜的沉积阻力下降了77%;炭砂滤柱还可以有效地吸附色氨酸类蛋白质和腐殖酸等有机物,使UV254由0.026 cm-1下降到0.020cm-1,使膜的孔堵阻力下降了约90%。将炭砂过滤工艺作为膜的预处理单元,其减缓膜污染的能力优于混凝工艺。

To investigate the effect of sand-carbon filtration on the performance of ultrafiltration membrane, the clarified water from the mechanical accelerated clarifier in a waterworks of Beijing was used to compare the operation characteristics, resistance and permeate quality of membrane filtration units between coagulation sedimentation/ultrafiltration （CU） process and coagulation sedimentation/sand-car- bon fihration/ultrafiltration （CSU） process. After the addition of sand-carbon filter, the increase rate of transmembrane pressure （TMP） of CSU process was only 0.29 kPa/d, much lower than the 1.23 kPa/d of CU process. The different membrane resistances were measured, and scanning electron microscopy and three-dimensional fluorescence technique were used to characterize the membrane surface and the perme- ate quality. It was found that the flocs in the sedimentation effluent were retained by sand layer of the sand-carbon filter, which reduced the cake resistance of membrane by 77%. The tryptophan-type aromat- ic protein and humic acid were retained by activated carbon layer of the sand-carbon filter, which decreased the UV254 of effluent from 0. 026 cm-1 to 0. 020 cm- 1, and reduced the blocking resistance of membrane by 90%. In conclusion, as a pretreatment unit, the sand-carbon filtration process was moreefficient in reversible and irreversible membrane fouling control than the coagulation process.