重金属捕集剂及陶瓷平板膜组合工艺对重金属污染土壤淋洗废水重复利用的研究

发布时间：2018-10-21 18:48

【摘要】：土壤淋洗是一种应用较为广泛的土壤重金属污染修复技术。而工程实际表明长久以来化学淋洗剂价格昂贵、淋洗废液难以处理以及淋洗剂难以回收利用成为该技术突破的重点和难点。本文以重金属污染土壤淋洗废水为研究对象,研究了重金属捕集剂破络合+陶瓷平板膜分离的组合工艺,并初步验证了该工艺在目前应用最为广泛的人工及天然螯合剂类淋洗剂领域内的技术可行性,并通过对组合工艺的处理效果的探索,总结出针对人工及天然螯合剂处理重金属污染废水的膜化学反应器的设计方案。采用五类重金属捕集剂固体DTCR、液体DTCR、固体TMT、液体TMT、重金属捕捉剂HMC-M1对初始铜离子浓度为50mg/L和500mg/L的模拟淋洗废水进行处理后,发现对于铜、镉、铅而言,重金属捕集剂HMC-M1的捕集效率明显优于其他四类。此外,通过反应后出水的提取方式对比,采用220nm的微滤陶瓷平板膜,在提取液的铜、镉、铅离子含量和模拟淋洗效率方面,都优于普通的静置沉淀取上清液的方式。通过对铜、镉、铅污染土壤淋洗废水和复合污染土壤淋洗废水进行试验,发现对于不同浓度的几类废水而言,p H、温度、搅拌时间的影响不大,主要影响因素是捕集剂投加质量与废水中EDTA理论含量之比(M/E)、搅拌强度。对于模拟铜、镉、铅及其复合污染土壤淋洗废水而言,最佳反应条件是:不调节p H、常温、投加比为1.4、搅拌强度为140r/min、搅拌时间为5min。在此条件下,无论废水中铜、镉、铅的初始浓度是50mg/L、100mg/L、300mg/L、500mg/L,处理后废水重金属离子去除率都达到95%以上,且处理后废水提取液的淋洗效率都达到对应量EDTA的80%以上,即该方法回收了淋洗废水中的EDTA。应用到广东省某临西场地的实际工业废水中发现:最佳反应条件是:不调节p H、温度,投加比为1.4,搅拌强度为180r/min、搅拌时间为5min。同时工业废水处理液的淋洗效率也达到对应量EDTA的80%以上,这表明该工艺可以应用到该场地的淋洗废水中。由于淋洗废水的EDTA原本与铜、镉、铅离子形成稳定的可溶性络合物,则其处理后的淋洗效率证明了HMC-M1在反应过程中打破了原有的络合平衡,并与铜、镉、铅离子形成新的难溶性络合物,同时释放出EDTA。本过程中主要有HMC-M1打破络合平衡释放EDTA和分离EDTA与M-(HMC-M1)两个方面,这契合了膜化学反应器反应和分离的特点。针对该过程设计一套膜化学反应器很有必要。由于原位土壤淋洗技术的阶段性、周期性。因而采用间歇式搅拌反应器对该废水进行处理。实验表明,该反应器的反应时间选用5min、沉淀时间选用30min、进水时间控制为10min,进水泵和加药泵同时工作,进水和加药10min后,陶瓷膜抽吸泵开始工作,20min后停止进水,开始膜的反冲洗以及排泥,膜清洗和排泥30min后,一个周期结束。此外,本系统采用两个膜反应器并联的方式,保证土壤淋洗出水1h内,淋洗废水一直可以得到处理。
[Abstract]:Soil leaching is a widely used remediation technique for heavy metal pollution. The engineering practice shows that for a long time, the high price of chemical eluent, the difficult treatment of leaching waste liquid and the difficulty of recovery and utilization of eluent have become the key and difficulty of this technology breakthrough. In this paper, the separation process of heavy metal trapping agent for the separation of complex ceramic plate membrane was studied with heavy metal contaminated soil leaching wastewater as the research object. The technical feasibility of this process in the field of artificial and natural chelating agents, which is the most widely used at present, has been preliminarily verified, and the treatment effect of the combined process has been explored. The design scheme of membrane chemical reactor for treatment of heavy metal polluted wastewater by artificial and natural chelating agents was summarized. Five kinds of heavy metal trapping agents solid DTCR, liquid DTCR, solid TMT, liquid TMT, heavy metal trapping agent HMC-M1 were used to treat simulated leaching wastewater with initial copper ion concentrations of 50mg/L and 500mg/L. The trapping efficiency of heavy metal trapping agent HMC-M1 is obviously better than that of other four kinds of trapping agents. In addition, through the comparison of the extraction methods of the effluent after the reaction, the content of copper, cadmium and lead ions in the extract solution and the simulated elution efficiency were superior to those of the ordinary static precipitation method in the extraction of supernatant by using the 220nm ceramic plate membrane. Through the experiments on leaching wastewater from copper, cadmium and lead contaminated soil and the leaching wastewater from compound polluted soil, it was found that, p H, temperature and stirring time had little effect on several kinds of wastewater with different concentrations. The main influencing factors are the ratio of mass of trapping agent to the theoretical content of EDTA in wastewater (M / E) and stirring intensity. For the simulated leaching wastewater of copper, cadmium, lead and its compound contaminated soil, the optimum reaction conditions are as follows: no regulation of pH, room temperature, adding ratio of 1.4, stirring intensity of 140 r / min, stirring time of 5 mins. Under these conditions, the initial concentration of copper, cadmium and lead in wastewater is 50 mg / L ~ (100) mg / L ~ (-1), and the removal rate of heavy metal ions is more than 95%, and the leaching efficiency of wastewater extract is above 80% of the corresponding amount of EDTA. That is to say, the EDTA. from leaching wastewater was recovered by this method. It was found that the optimum reaction conditions were as follows: no adjusting pH, temperature, adding ratio 1.4, stirring intensity 180 r / min, stirring time 5 min. At the same time, the leaching efficiency of the industrial wastewater treatment liquid is over 80% of the corresponding amount of EDTA, which indicates that the process can be applied to the leaching wastewater of the site. Because the EDTA of leaching wastewater formed a stable soluble complex with copper, cadmium and lead ions, the elution efficiency of HMC-M1 after treatment proved that HMC-M1 broke the original complexation equilibrium in the reaction process, and also with copper and cadmium. Lead ions form new insoluble complexes and release EDTA. In this process, HMC-M1 breaks the equilibrium of complex release EDTA and separates EDTA from M- (HMC-M1), which coincides with the characteristics of membrane reactor reaction and separation. It is necessary to design a membrane chemical reactor for this process. Because of the stage and periodicity of in situ soil leaching technology. Therefore, the wastewater was treated by batch stirred reactor. The experimental results show that the reaction time is 5 min, the precipitation time is 30 min, and the influent time is 10 min. The feed pump and the dosing pump work at the same time. After influent and dosing 10min, the ceramic membrane suction pump begins to work, and the 20min stops the influent. Start membrane backwashing and mud removal, membrane cleaning and mud removal 30min, one cycle ends. In addition, two membrane reactors were used in the system to ensure that the leaching wastewater could be treated all the time within 1 h.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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