Water Treatment by Submerged Membrane Separation in Sedimentation Tank with Powdered Activated Carbon Dosage

研究开发了一种微滤膜组件浸没在沉淀池中的饮用水处理系统。该系统可以承受洪水期间的重悬浮固体污染，但它不能去除溶解的有机物质，如难闻的味道和气味。粉状活性炭（PAC）可用于去除有机物质，但会干扰膜分离。为了研究PAC对膜分离的影响，采用磁力搅拌器驱动的小型膜模块进行了恒压过滤实验。原水是被处理过的污水污染的河水。测试了添加PAC和不添加PAC的不同压力组。采用反冲洗法和化学冲洗法确定膜系统的可行性。PAC的加入对膜分离没有影响，反而延缓了膜的堵塞。添加PAC后膜的阻力增幅明显小于未添加PAC的膜，过滤压力高的膜阻力大于过滤压力低的膜阻力。高压模组与低压模组之间的通量差异不大。对进水进行曝气，使悬浮物不沉淀，阻力减小。在高过滤压力下，膜层和表面堆积层被压缩，阻力增大。这意味着较低的过滤压力会延长堵塞膜，并在化学洗涤之间的过滤循环中产生更多的水。比阻力小的PAC或淤泥的高悬浮固体浓度不会影响过滤，反而会阻止增加阻力的细颗粒的积累。验证了PAC应用于膜分离的可行性。

The researcher developed potable water treatment system by micro-filtration membrane modules submerged in sedimentation tanks. The system can stand for heavy suspended solid lording during a flood, however it can not remove dissolved organic substances such as bad taste and odor.Powdered Activated Carbon (PAC) can be added to remove organic substances, but it may disturb membrane separation.To investigate the effect of PAC on membrane separation, constant pressure filtration experiments were conducted using small membrane modules that were driven by a magnetic stirrer. The raw water was river water polluted by treated sewage. Different sets of pressure with PAC addition or without PAC were tested. Back-washing and chemical washing were also applied to determine feasibility of the membrane system.Addition of PAC did not disturb membrane separation at all and it rather delayd clogging of membrane. Increase rate of resistance of membrane with PAC was apparently smaller than that of without PAC.Resistance of membranes of higher filtration pressure was larger than that of lower pressure modules. There was not much difference of flux between the high pressure modules and the lower pressure ones. When the feed water was aerated and suspended solid was kept from settled, the resistance decreased.The membrane and accumulated layr on the surface were compressed and the resistance increased, when high filtration pressure was applied. This means that lower filtration pressure extends clogging membrane and produces more water during a filtration cycle between chemical washings. The high suspended solid concentration of PAC or silt of which specific resistance is small will not affect filtration and rather prevents accumulation of fine particles that increase resistance. The feasibility of applying PAC at membrane separation was confirmed.