微涡旋絮凝—逆流气浮—纳滤集成工艺去除水中腐殖酸的动态运行特征

Humic acid removal by micro-eddy flocculation, counter current dissolved air flotation and nanofiltration

通过微涡旋絮凝—逆流气浮—纳滤集成工艺的动态试验研究,确定其运行周期为72h,能很好地去除水中腐殖酸有机物,但不同纳滤膜组成的集成工艺处理效果不同。采用PACl絮凝剂处理水样2时,以流程1运行的含TQ5636FC型纳滤膜的集成工艺出水的高锰酸盐指数为0.45mg/L,UV254nm在0.0033左右波动,且有95%以上的脱盐率。以流程2运行的含MN1812A型纳滤膜的集成工艺处理3种水样时的膜清水的高锰酸盐指数在0.75mg/L左右波动,UV254nm大都远小于0.0075,有时甚至为0。水样1和水样3的UV254nm平均值为0.0054,水样2的最低,平均值为0.0033,脱盐率只有6%～10%。以PACl为絮凝剂时,集成系统有较强的适应原水水质变化的能力。预处理中活性炭柱的存在提高了MN1812A型纳滤膜清水样的水质,但并没有延长膜的使用周期。这也表明膜的污染更重要的是来自无机物的污染。

Integreated treatment of micro-eddy flocculation （MEF）, counter current dissolved air flotation （CCDAF） and nanofiltration （NF） was performed on three influents-tapwater spiked with humic acid at 5 mg/L, 10 mg/L and 10 mg/L＋5 mg/L of Gaolin clay. After 72 hours of continuous operation, the treatment was interrupted for washing of the NF unit membrane to restore it original flux. The MEF-CCDAF-NF treatment effectively removed humic acid with much better TDS removal achieved using TQ56-36FC NF （Omnipure Filter Company） than M- N1812A NF （Applied Membranes INC）. The use of PACl flocculant helped to maintain the excellent treatment performance following a significant change in the feed composition. Some inorganic constituents of the NF feed were responsible for the membrane fouling since the flux reduction was not altered by the additional pretreatment of the NF feed by carbon adsorption for removing most of its organic constituents.