中文摘要：

以北京市某水厂冬季沉后水为研究对象,分别采用常规过滤工艺和强化过滤工艺对其进行处理.通过改变聚合氯化铝（PACl）投加量、滤料粒径d和微絮凝时间,并结合水头损失、颗粒数、总有机碳（TOC）、化学需氧量（COD）等实验数据,对低温低浊水体强化过滤工艺条件进行了研究.结果表明,强化过滤工艺与常规过滤工艺相比具有较强的除浊、去除有机物和颗粒物的能力,当微絮凝时间为2min时可以得到较好的过滤效果;PACl投药量为1.5mg·L^-1时,浊度可降到0.04NTU,而常规过滤工艺最多只能将浊度降到0.2NTU.在滤料选用方面,当滤料粒径d=0.6～1.2mm时滤后水中颗粒数（2～5μm）、浊度、COD等指标均达到最优值.同时,电感耦合等离子体光谱（ICP-OES）检测结果表明,滤后水中Al3＋含量小于0.2mg·L^-1,并未因二次投加PACl而升高,因此,不会对水的饮用产生任何健康和安全风险.

英文摘要：

Water samples from the settling tank of a water plant were collected during the winter in Beijing to comparatively study the treatment of low temperature and low turbidity water using both conventional and enhanced filtration processes. Based on the head loss,particle counts,TOC and COD, the operating conditions including PACl dosage,particle size of filter medium,and the coagulation time were optimized for the enhanced filtration process of micro-flocculation. In comparison with conventional filtration,the enhanced process facilitates the removal of turbidity,organics and particles. Better results are obtained for the micro-flocculation and enhanced filtration process when the coagulation time is set to 2 minutes,and the turbidity can be lowered to 0. 04 NTU with a dosage of 1.5 mg·L^-1 PACl,while it is reduced only to 0. 2 NTU for the conventional filtration process. In the selection of filtration medium,silica sand of d= 0.6～1.2 mm was found to be the most efficient for the removal of 2 ～ 5 μm particle counts,turbidity and COD in the outflow of the filtered water. Furthermore,aluminum contents were measured by ICP-OES to be less than 0. 2 mg·L^-1,showing that no significant increase in the Al content of the filtered water resulted from the second dosing of PACl in the micro-flocculation process,and thus the process added no health and safety risk to the drinking water.