双膜法处理污水厂尾水效能分析与膜再生研究

为提高污水厂出水水质,寻求适合处理污水厂尾水滤膜的再生方法,采用超滤—纳滤双膜工艺,针对辽宁省本溪市某城市污水厂二级尾水开展深度处理研究。考察了进水流速、累积过滤水量(超滤进水流速为25 L/min,纳滤进水流速为4 L/min)对膜分离效果的影响,同时开展了超滤和纳滤膜再生方式及效果研究。结果表明:在考察范围内,超滤装置的分离性能受进水流速影响较小,主要与进水污染程度有关,对COD、TP、氨氮的平均去除率分别为48%、55%、27%。当纳滤单元进水流速为4 L/min时,双膜法对COD、TP、氨氮的平均去除率分别为87%、96%、68%。双膜法对COD、TP的去除率随着进水污染程度的减轻而降低,氨氮去除率受累积过滤水量的影响较小,这与原水污染程度有关。随着累积过滤水量的增加,膜分离性能呈减弱趋势。超滤膜轻微污染时采用物理清洗效果良好,严重污染时需采用化学清洗的方法。超滤有效延缓了纳滤膜污染,纳滤膜轻微污染时采用酸碱浸泡法再生效果良好。

Efficiency Analysis and Membrane Regeneration of Tail Water Treatment in Wastewater Treatment Plant by Double Membrane Method

In order to improve effluent quality of a wastewater treatment plant and explore regeneration methods of filtration membrane suitable for treating the tail water of the wastewater treatment plant,an ultrafiltration-nanofiltration double membrane process was applied in a pilot study on advanced treatment of secondary tail water from a municipal wastewater treatment plant in Benxi City,Liaoning Province.The influences of influent flow rate and cumulative filtered water volume(ultrafiltration influent flow rate was 25 L/min and nanofiltration influent flow rate was 4 L/min)on membrane separation were investigated,and regeneration methods and effects of the ultrafiltration and nanofiltration membranes were explored.The separation performance of the ultrafiltration device was less affected by the influent flow rate in the experiment,which was mainly related to the ultrafiltration degree of influent pollution.Average removal rates of COD,TP and ammonia nitrogen by the ultrafiltration device were 48%,55%and 27%,respectively.When the influent flow rate of the nanofiltration unit was 4 L/min,the average removal rates of COD,TP and ammonia nitrogen by the double membrane process were 87%,96%and 68%,respectively.The removal rates of COD and TP by the double membrane method decreased with the reduction of influent pollution degree,and the ammonia nitrogen removal rate was less affected by the cumulative filtered water volume,which was mainly related to the degree of raw water pollution.The membrane separation performance decreased with the increase of the cumulative filtered water volume.When the ultrafiltration membrane was slightly fouled,the physical cleaning effect was good.When the ultrafiltration membrane was seriously fouled,chemical cleaning was required.Ultrafiltration effectively delayed the nanofiltration membrane fouling,and the slight fouling of the nanofiltration membrane was well regenerated by acid-base soaking.