微絮凝直接过滤工艺处理效果的试验研究

发布时间：2018-08-11 15:53

【摘要】：我国的小城镇及农村地区普遍面临着饮用水水源污染的饮用水安全问题。以常规水处理工艺处理浊度较低的水库水源水时，通常存在絮凝剂的投药量较高或需要投加附加微粒的问题。由于小城镇及农村地区经济水平和管理能力有限，针对村镇供水特点选择经济有效的净水工艺十分必要。微絮凝直接过滤工艺是适用于水库水等浊度不高水源的净水工艺，其省去了混凝沉淀步骤，混凝过程完全在滤床内进行，可节省净水厂的占地面积、降低工程投资与制水成本。论文研究了采用聚合氯化铝和硫酸铝时微絮凝直接过滤工的处理效果，试验结果表明，投加硫酸铝作为絮凝剂时的除浊效果优于聚合氯化铝，在进水浊度15NTU~20NTU，滤速10m/h时，投加14mg/L硫酸铝混凝剂可使连续12h过滤周期内的出水浊度达标，平均出水浊度0.57NTU。可通过投加助滤剂来进一步提高出水水质，在投加硫酸铝10mg/L的条件下，分别复配投加聚二甲基二烯丙基氯化铵（PDMDAAC）、壳聚糖（CTS）、非离子型聚丙烯酰胺（NAPM）和阴离子型聚丙烯酰胺（APAM）四种助滤剂0.1mg/L均会取得较好的除浊效果，可保证12h运行周期出水浊度达标且满足水损要求，具有较好的助滤效果，周期内平均出水浊度分别为0.36NTU、0.60NTU、0.52NTU和0.68NTU。微絮凝直接过滤工艺对腐殖酸具有一定的去除效果，对腐殖酸的去除主要是通过去除浊度来得到实现的。在仅投加10mg/L硫酸铝时对腐殖酸的去除率在30%左右，分别复配PDMDAAC、CTS、NPAM和APAM时的去除率分别提高到58%，55%，53%和50%。在水处理过程中，使用铝盐混凝剂可能会导致出水残余铝升高。试验结果表明混凝剂的投药量对出水残余铝浓度影响显著，当混凝剂投药量超过最佳投药量时，出水残余铝会显著升高。增加硫酸铝投药量至18mg/L时，出水残余铝达到0.182mg/L，处于较高的水平。在过滤过程中去除的主要是颗粒铝，在过滤周期内出水残余铝与出水浊度由较好的相关性。在相同铝盐絮凝剂投药量的条件下，，投加助滤剂可以提高对浊度的去除率，进而可降低出水残余铝浓度。在四种助滤剂中，壳聚糖对残余铝的控制效果是最明显的。天然高分子絮凝剂壳聚糖分子表面含有丰富的游离氨基和羟基，对溶液中的金属离子有较强的吸附、配位作用。试验结果表明，投加壳聚糖不仅仅通过去除浊度来除去颗粒铝，其可以通过与铝离子的螯合作用去除溶解铝，使出水残余铝进一步降低。壳聚糖与硫酸铝复配连用时，壳聚糖投药量在0.1mg/L~0.2mg/L即可使出水残余铝稳定在较低水平，降低了出水铝超标的风险。
[Abstract]:Small towns and rural areas in China are generally faced with drinking water safety problems caused by drinking water source pollution. In the treatment of reservoir source water with low turbidity by conventional water treatment process, the problem of high dosage of flocculant or the need of adding additional particles is usually existed. Because of the limited economic level and management ability in small towns and rural areas, it is necessary to select economical and effective water purification technology according to the characteristics of water supply in villages and towns. Micro-flocculation direct filtration process is suitable for purifying water with low turbidity, such as reservoir water. It saves the coagulation and sedimentation steps, and the coagulation process is carried out completely in the filter bed, which can save the land area of the water purification plant and reduce the project investment and water production cost. In this paper, the treatment effect of micro-flocculation direct filter with polyaluminum chloride and aluminum sulfate was studied. The experimental results showed that the turbidity removal effect of adding aluminum sulfate as flocculant was better than that of polyaluminum chloride, when the turbidity of influent was 15NTU 20NTU, and the filtration rate was 10m/h. Adding 14mg/L aluminum sulfate coagulant can make the turbidity of effluent reach the standard in the continuous filtration period of 12 hours, and the average turbidity of the effluent is 0.57 NTU. The effluent quality can be further improved by adding filter aids. Under the condition of adding aluminum sulfate 10mg/L, Adding polydimethyldiallylammonium chloride (PDMDAAC),) chitosan (CTS), (CTS), Nonionic polyacrylamide (NAPM) and anionic polyacrylamide (APAM) respectively with four kinds of filter aids 0.1mg/L can achieve better turbidity removal effect. It can ensure that the turbidity of effluent reaches the standard and meets the requirement of water loss in 12h operation cycle. The average turbidity of effluent is 0.36NTU 0.60NTU 0.52NTU and 0.68NTU, respectively, and the average turbidity of effluent is 0.36NTU 0.60NTU0.52 NTU and 0.68NTU respectively. The micro-flocculation direct filtration process has a certain removal effect on humic acid, and the removal of humic acid is mainly achieved by removing turbidity. The removal rate of humic acid was about 30% when 10mg/L aluminum sulfate was added only, and the removal rate of NPAM and APAM were increased to 55.55% and 50% respectively. In the process of water treatment, aluminum salt coagulant may lead to the increase of residual aluminum in effluent. The results show that the dosage of coagulant has a significant effect on the concentration of residual aluminum in effluent. When the dosage of coagulant exceeds the optimal dosage, the residual aluminum in effluent will increase significantly. When the dosage of aluminum sulfate is increased to 18mg/L, the residual aluminum in the effluent reaches 0.182 mg / L, which is at a higher level. In the filtration process, the main removal is granular aluminum, and the residual aluminum in the effluent has a good correlation with the turbidity of the effluent during the filtration period. Under the condition of the same dosage of aluminum salt flocculant, the removal rate of turbidity can be increased by adding filter aid, and the residual aluminum concentration in effluent can be reduced. Among the four filter aids, chitosan is the most effective in controlling residual aluminum. There are abundant free amino and hydroxyl groups on the surface of natural polymer flocculant chitosan, which can strongly adsorb and coordinate metal ions in the solution. The results show that adding chitosan can not only remove granular aluminum by removing turbidity, but also remove dissolved aluminum by chelating with aluminum ion, thus further reducing residual aluminum in water. When chitosan was combined with aluminum sulfate, the dosage of chitosan in 0.1mg/L~0.2mg/L could stabilize the residual aluminum in the effluent at a lower level, and reduce the risk of excess aluminum in the effluent.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU991.2

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