混凝—微滤去除水中腐殖酸的试验研究

发布时间：2018-02-04 04:26

  本文关键词： 混凝 微滤 给水 腐殖酸 膜污染　出处：《沈阳建筑大学》2013年硕士论文　论文类型：学位论文

【摘要】：饮用水的质量直接关系到人们的身体健康,随着污染的加剧与饮用水标准的严格,如何去除水中的污染物来保障饮用水安全,已经成为了水处理技术中的热门问题。天然有机物是水中消毒副产物的前体物,而腐殖质是地面水源中含量最高的天然有机物。 本文选用混凝-微滤工艺处理给水中的腐殖酸,通过水温、pH、腐殖酸浓度、混凝剂投加量、混凝剂种类五种因素考察对腐殖酸去除率、铁离子残留量和浊度去除率的影响。运用正交试验法分析这些因素的最优方案与对腐殖酸去除率与膜污染的影响主次,分析膜污染的机理,主要结论如下： 在不投加混凝剂直接膜过滤时,腐殖酸的去除率仅为12.8%,而加入混凝剂后,可以达到90%以上。各个因素对混凝-微滤工艺运行的影响趋势也有所不同。水温、腐殖酸浓度对运行效果的影响是成正比关系的,而pH则相反,pH越高,工艺运行效果越差。混凝剂投加量对其影响并不是呈线性关系的,在投加量为0.6mmol/L时,工艺运行的效果最好。三氯化铁的腐殖酸去除效率要比聚合氯化铁高,而铁离子的残留量与浊度去除率也是三氯化铁高与聚合氯化铁。 混凝-微滤工艺的去除效率与膜污染程度在一定程度上取决于混凝后絮体的形成状态,不同理化性质的混凝絮体形成的泥饼层有所不同。吸附在膜表面的颗粒越小,颗粒之间的缝隙就越小,形成的泥饼层就比较致密,膜阻力较大。此时透过膜的的颗粒都是粒径相对较小的,而小粒径的颗粒往往对膜孔产生较严重的污染。 通过正交试验的分析可知,混凝-微滤工艺对腐殖酸去除效率的四个影响因素中,混凝剂投加浓度对工艺的腐殖酸去除效率影响最大,其次是pH和腐殖酸浓度,影响最小的为水温。最优工艺条件为：腐殖酸浓度为6mg／L、水温10-C、pH为6、混凝剂浓度为0.6mmol/L,工艺在此组合条件下对腐殖酸的去除效率最高。混凝-微滤工艺去除饮用水中腐殖酸的Jt／Jo值最优工艺条件为：腐殖酸浓度为6mg/L、水温20℃、PH为6、混凝剂浓度为1mmol/L。其中,混凝剂浓度对膜污染的影响最大,其次是腐殖酸浓度和水温,影响最小的为pH。
[Abstract]:The quality of drinking water is directly related to people's health. With the intensification of pollution and strict standards of drinking water, how to remove pollutants in water to ensure the safety of drinking water. Natural organic matter is the precursor of disinfection by-product in water, and humus is the most abundant natural organic substance in surface water source. In this paper, the humic acid in feed water was treated by coagulation-microfiltration process. The removal rate of humic acid was investigated by five factors: water temperature, humic acid concentration, coagulant dosage and coagulant type. The effects of iron ion residue and turbidity removal efficiency were analyzed by orthogonal test. The optimal scheme and the effect on humic acid removal efficiency and membrane fouling were analyzed by orthogonal test. The mechanism of membrane fouling was analyzed. The main conclusions were as follows: The removal rate of humic acid was only 12.8when direct membrane filtration was not added with coagulant, but after adding coagulant. The effect of different factors on the operation of coagulation-microfiltration process is different. The effect of water temperature and humic acid concentration on the operation effect is proportional, but pH is the opposite. The higher the pH, the worse the operation effect of the process. The effect of coagulant dosage on it is not linear, when the dosage is 0.6 mmol / L. The humic acid removal efficiency of ferric trichloride is higher than that of polyferric chloride, and the removal rate of iron ion residue and turbidity is also higher than that of polyferric chloride and ferric trichloride. The removal efficiency and membrane fouling degree of coagulation-microfiltration process depend to some extent on the formation of flocs after coagulation. The smaller the particles adsorbed on the surface of the membrane, the smaller the gap between the particles, and the denser the mud cake layer formed. At this time, the particles passing through the membrane are relatively small in size, and the particles with small particle size tend to pollute the membrane pore seriously. Through the analysis of orthogonal experiment, we can know that the coagulation-microfiltration process has the greatest influence on the removal efficiency of humic acid among the four factors which affect the removal efficiency of humic acid. The optimum technological conditions are as follows: humic acid concentration is 6 mg / L, water temperature is 10 ~ (-C), pH is 6, coagulant concentration is 0.6 mmol / L. The optimum Jt/Jo value of coagulation-microfiltration process for removal of humic acid in drinking water was as follows: humic acid concentration was 6 mg / L, water temperature was 20 鈩，

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