试验研究了微涡旋絮凝-逆流气浮-纳滤集成工艺去除水中腐殖酸的工艺特征和效果.试验结果表明,微涡旋絮凝-逆流气浮工艺去除水中腐殖酸时,在聚合氯化铁(PFC)的最佳投药点0.62 mmol·L^-1(Fe^3+)下,出水水质符合纳滤膜系统预处理单元的要求,而且该工艺需要PFC絮凝剂的量较低.该预处理系统与纳滤系统组合的集成工艺可以使水中的腐殖酸有机物浓度大大降低,且含TQ56-36FC型纳滤膜的流程1比含M-N1812A型纳滤膜的流程2效果好.前者出水的TOC值可达0.48 mg·L^-1,CODMn值为0.64~0.69mg·L^-1,UV254值为0,且有95%以上的脱盐率.后者出水的TOC值为0.61~1.00mg·L^-1,CODMn值为0.72~0.97mg·L^-1,UV254值为0~0.0109,脱盐率很低.另外,尽管保安过滤/活性炭预处理有利于纳滤膜出水水质的提高,但活性炭柱的存在也降低了纳滤膜对有机物的去除率.动态实验结果表明,该集成工艺在本试验中运行周期为72h.水中颗粒物粒度分布表明,原水、絮凝后和气浮出水中颗粒物粒度分布的中位直径(d50)分别为2~5 μm、21 μm和16μm;经过保安过滤器或保安过滤器/活性炭柱,水样中的颗粒物的d50为0到几个μm;经过纳滤膜后,出水基本无颗粒物.初步研究表明,微涡旋絮凝过程中投药量对絮体的分形维数有着显著影响.
The integrated process of micro-eddy floccnlation (MEF)-counter current dissolved air flotation (CCDAF)-nanofiltration (NF) was used to remove humic acid in water, and its characteristics and effects were studied. The results showed that water quality of MEF-DAF process could meet the need of pre-unit for membrane system at optimum dosage of PFC flocculant. This dosage is less than that in flocculation-sediments process. The MEFCCDAF-NF integrated process could remove most of humic in water, and flowage one with TQ56-36FC NF unit had better performance than flowage two with M-N1812A one. It could be demonstrated by the better quality of effluent water after flowage one : 0.48mg·L^-1 of TOC, 0.64 - 0.69 mg·L^-1 of CODM., no UV254 absorbanee, and only 5 % residual TDS than that after flowage two : 0.61 - 1.00 mg·L^-1 of TOC, 0, 72 ~ 0.97mg·L^-1of CODMn,0 ~ 0. 0109 of UV254 , and high TDS content, Moreover, the NF permeat quality could he improved when activated carbon (AC) unit following MF, but some kinds of organics in water could be catch by both AC and NF units, leading to decreasing the stepwise removal rate for organics in water by NF unit, The integrated process dynamic period of 72 h was demonstrated by the related experiments. The d50 values of particle size distribution (PSD) in raw water, flocculated one and floated one are 2 ~5μm, 21μm and 16μm, respectively. Sometimes particles in water with several microns of d50, could still be found after MF or MF-AC units, and no particles exist in NF permeat. The primary study results showed that PFC dose had remarkable effect on fraetal dimensions of flocs in MEF unit,