絮凝剂对活性污泥的毒性研究

发布时间：2018-09-11 16:13

【摘要】：在污水处理中大量使用的絮凝剂对污水处理过程产生了一定的毒性影响,处理后的污水中也会残留部分絮凝剂相关成分,不合理的絮凝剂用量可能会对污水处理的效果有坏的影响,使得成本增加,因此了解絮凝剂对污水处理系统的毒性,并且使应用到污水处理中絮凝剂的用量合理化是十分必要的,能有效减小因絮凝剂的使用对污水处理系统造成的危害,并减少排放到自然水体中絮凝剂的量,减小二次污染。为了研究絮凝剂对污泥活性的影响,本课题研究了污水处理过程中常用的几类絮凝剂对污水处理系统中活性污泥活性指标产生的影响,分别选取硫酸铁(FS)、聚合硫酸铁(PFS)、聚合硅酸硫酸铁(PFSS)、氯化铝(AlCl3)、聚合氯化铝(PAC)、聚合硅酸氯化铝(PASC)、阴离子聚丙烯酰胺(APAM)、阳离子聚丙烯酰胺(CPAM)、壳聚糖(CTS)作为无机絮凝剂和有机絮凝剂的代表物,采用呼吸速率、脱氢酶活性、硝化速率三种活性污泥中微生物活性指标考察絮凝剂对活性污泥中微生物的毒性影响。并对三种毒性指标的灵敏度,操作难易程度,所产生的环境毒性大小做对比,选择出了最佳方法。研究结果如下:(1)九种絮凝剂对活性污泥毒性较大的是APAM、CPAM和PFS;毒性最小的是PAC,其次是PFSS。PAC对呼吸速率、脱氢酶活性和硝化速率的EC50值分别为1.520、2.309、0.283 g/L;PFSS对呼吸速率、脱氢酶活性和硝化速率的EC50值分别为1.113、1.391、0.273 g/L。建议在使用时优先选择PAC和PFSS,并应严格控制进入污水处理系统中的人工合成有机絮凝剂的量。(2)三种铁盐和三种铝盐絮凝剂对活性污泥的三个活性指标呼吸速率、脱氢酶活性、硝化速率的毒性有着一致的顺序,分别为PFSFSPFSS、PASCAlCl3PAC;三种有机絮凝剂对脱氢酶活性的毒性顺序为APAMCPAMCTS,对硝化速率的毒性影响顺序为CPAMAPAMCTS。(3)铁盐和铝盐毒性大小与pH值和铁铝形态有关,使活性污泥溶液pH值下降幅度越大对活性污泥的毒性影响越大,铁盐中毒性作用较强的是聚合态铁,铝盐中毒性作用较强的是离子态铝。PAM比CTS毒性大,是因为PAM会被分解为有毒单体,而CTS不会产生有毒物质。(4)比较三种活性污泥毒性指标得出,硝化速率法为最优方法,其次是呼吸速率法,最后是脱氢酶活性法,聚丙烯酰胺不适合使用呼吸速率法。
[Abstract]:A lot of flocculants used in wastewater treatment have a certain toxic effect on the process of sewage treatment, and some flocculant related components will be left in the treated sewage. Unreasonable dosage of flocculant may have a bad effect on the effect of sewage treatment and increase the cost, so understand the toxicity of flocculant to sewage treatment system, It is necessary to rationalize the amount of flocculant used in wastewater treatment, which can effectively reduce the harm caused by the use of flocculant to sewage treatment system, reduce the amount of flocculant discharged into natural water and reduce secondary pollution. In order to study the effect of flocculant on sludge activity, the influence of several kinds of flocculants used in wastewater treatment on activated sludge activity index in sewage treatment system was studied in this paper. Ferric sulfate (FS), polyferric sulfate (PFS), polysilicate ferric sulfate (PFSS), aluminum chloride (AlCl3), polyaluminium chloride (PAC), polysilicate aluminum chloride (PASC), anionic polyacrylamide (APAM), cationic polyacrylamide (CPAM), chitosan (CTS) were selected as inorganic flocculants. The representative of an organic flocculant, The effects of flocculant on the toxicity of microorganisms in activated sludge were investigated by means of respiration rate dehydrogenase activity and nitrification rate. The sensitivity of the three toxic indexes, the degree of difficulty in operation and the magnitude of environmental toxicity are compared, and the best method is selected. The results were as follows: (1) APAM,CPAM and PFS; were the least toxic to activated sludge, followed by PFSS.PAC and PFSS.PAC, the EC50 values of dehydrogenase activity and nitrification rate were 1.520 ~ 2.309 ~ 0.283 g / L ~ (-1) 路L ~ (-1) 路L ~ (-1) 路L ~ (-1) 路L ~ (-1) 路L ~ (-1) 路L ~ (-1), respectively. The EC50 values of dehydrogenase activity and nitrification rate were 1.113 ~ 1.391g / L and 0.273 g / L, respectively. It is suggested that PAC and PFSS, should be selected first and the amount of synthetic organic flocculants entering wastewater treatment system should be strictly controlled. (2) the respiration rate and dehydrogenase activity of three kinds of ferric salts and three kinds of aluminum salt flocculants for activated sludge should be strictly controlled. The order of toxicity of nitrification rate was that the toxicity order of three organic flocculants of PFSFSPFSS,PASCAlCl3PAC; to dehydrogenase activity was CPAMAPAMCTS. (3) the toxicity of iron salt and aluminum salt was related to the pH value and the form of iron and aluminum, and the order of toxicity of APAMCPAMCTS, to the nitrification rate was that the toxicity of CPAMAPAMCTS. (3) iron salt and aluminum salt was related to the pH value and the form of iron and aluminum. The larger the decrease of pH value of activated sludge solution is, the greater the toxicity of activated sludge is. The more toxic effect of iron salt is polymerized iron, the more toxic effect of aluminum salt is that ionic aluminum. PAM is more toxic than CTS. This is because PAM is decomposed into toxic monomers, while CTS does not produce toxic substances. (4) comparing three toxic indexes of activated sludge, nitrification rate method is the best method, followed by respiratory rate method and dehydrogenase activity method. Polyacrylamide is not suitable for respiratory rate method.
【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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