School of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100022, China.
Water Sci Technol. 2009;60(9):2337-43. doi: 10.2166/wst.2009.684.
The newly issued National Drinking Water Standard required that turbidity should be lower than 1 NTU, and the substitution of sand filtration by immersed ultrafiltration (immersed-UF) is feasible to achieve the standard. This study aimed to optimise the operational processes (i.e. aeration, backwashing) through pilot scale studies, to control membrane fouling while treating the sedimentation effluent. Results indicated that the immersed-UF was promising to treat the sedimentation effluent. The turbidity was below 0.10 NTU, bacteria and E. coli were not detected in the permeate water. The intermittent filtration with aeration is beneficial to inhibit membrane fouling. The critical aeration intensity is observed to be 60.0 m(3) m(-2) h(-1). At this aeration intensity, the decline rate of permeate flux in one period of backwashing was 1.94% and 7.03% for intermittent filtration and sustained filtration respectively. The different membrane backwashing methods (i.e. aeration 1.5 min, synchronous aeration and water backwashing 2 min, water backwashing 1.5 min; synchronous aeration and water backwashing 3 min, water backwashing 2 min; aeration 3 min, single water backwashing 2 min; synchronous aeration and water backwashing 5 min; single water backwashing 5 min) on the recovery of permeate flux were compared, indicating that the synchronous aeration and water backwashing exhibited best potential for permeate flux recovery. The optimal intensity of water backwashing is shown to be 90.0 L m(-2) h(-1). When the actual water intensity was below or exceeded the value, the recovery rate of permeate flux would be reduced. Additionally, the average operating cost for the immersed UF membrane, including the power, the chemical cleaning reagents, and membrane modules replacement, was about 0.31 RMB/m(3).
新发布的《国家饮用水标准》要求浊度低于 1NTU，砂滤替代浸没式超滤（浸没式 UF）是实现该标准的可行方法。本研究旨在通过中试研究优化操作工艺（即曝气、反冲洗），控制膜污染，同时处理沉淀出水。结果表明，浸没式 UF 有望处理沉淀出水。浊度低于 0.10NTU，渗透水中未检出细菌和大肠杆菌。间歇曝气过滤有利于抑制膜污染。临界曝气强度为 60.0m³/m²·h。在此曝气强度下，反冲洗一个周期内间歇过滤和连续过滤的渗透通量下降率分别为 1.94%和 7.03%。不同的膜反冲洗方法（即曝气 1.5min、同步曝气和水反冲洗 2min、水反冲洗 1.5min；同步曝气和水反冲洗 3min、水反冲洗 2min；曝气 3min、单水反冲洗 2min；同步曝气和水反冲洗 5min；单水反冲洗 5min）对渗透通量恢复的影响进行了比较，表明同步曝气和水反冲洗对渗透通量恢复具有最佳潜力。最佳水反冲洗强度为 90.0L/m²·h。当实际水强度低于或超过该值时，渗透通量的恢复率将会降低。此外，浸没 UF 膜的平均运行成本，包括电力、化学清洗试剂和膜组件更换，约为 0.31 元/m³。
