混凝/浸没式超滤膜工艺处理微污染地表水的运行工况和处理效果研究

Pilot study of coagulation/immersed ultrafiltration treatment of micro-polluted surface water

为了考察混凝/浸没式超滤膜工艺处理微污染地表水时影响跨膜压差增长的因素和对污染物的去除能力,采用实验室小试装置进行试验研究,保持工艺系统出水水量基本不变,观察不同运行工况下跨膜压差的变化,分析混凝剂投加量、混凝反应水箱水力停留时间、曝气强度对膜污染的影响,并考察采用低浓度碱液对膜进行在线清洗的效果,以及混凝/浸没式超滤工艺对污染物的去除效果。结果表明:混凝反应水箱的水力停留时间对膜污染影响较小,停留时间分别为10 min和0 min下运行,跨膜压差增长值接近;混凝剂投加量对膜污染影响较大,硫酸铝(以Al3+计)4 mg/L的投加量对膜污染改善比较好,继续增加投加量对膜污染的改善效果没有明显提高;曝气强度在20 m3/(m2.h)以下时,曝气量越大,对膜污染的改善越好;利用低浓度NaOH溶液进行在线化学清洗可以使跨膜压差得到有效的降低;该工艺的出水浊度保持在0.1 NTU以下,对CODMn和UV254的去除率分别能达到47%和54%。

The influences of the trans-membrane pressure across the coagulation/immersed ultrafiltration on the treatment of micro-polluted surface water and the removal abilities of polluted matter by this process were investigated in a pilot program.The laboratory scale device kept the filtration flux constant while the influences of the membrane fouling were analyzed as a function of the coagulant dosage,coagulation reaction time and aeration intensity.The effect of in-line chemical cleaning of the membrane for low concentrations of NaOH was also analyzed.The experiments also studied the pollutant removal ability of the coagulation/ultrafiltration.The results showed that the coagulation reaction time had little effect,and the increments of trans-membrane pressure were similar for the hydraulic retention times in the coagulation tank of 0 min and 10 min.The effect of the coagulant dosage is quite significant with the dosage of 4 mg/L（Al3＋） the best dosage for reducing the membrane fouling.With an aeration intensities of less than 20 m3/m2·h,higher aeration intensities improves removal of the membrane fouling.The CODMn removal efficiency was 47% and the UV254 by this process was 54%.The effluent turbidity was kept below 0.1 NTU.