基于敏感因子指数法的垃圾填埋场地下水污染过程识别技术研究

发布时间：2018-10-11 13:34

【摘要】：垃圾渗滤液的泄漏对四周水、土环境造成的污染日益严重,已然成为一个世界性的环境问题,而其产生就主要来自于城市垃圾卫生填埋。因为垃圾渗滤液是一种成分十分复杂的污水,其渗入水体对地下水造成严重污染,进而严重威胁到地下水的安全使用。垃圾渗滤液泄漏进入地下含水层中会形成不同的氧化还原带,从热力学原理以及生物地球化学作用的角度上来看,与污染场地相距最近的位置会首先形成产甲烷带,然后随着距离的增长再依次形成硫酸盐还原带、铁还原带、锰还原带、硝酸盐还原带以及氧还原带。这些不同氧化还原环境的出现对于研究含水层中污染物的降解作用以及地下水污染的控制与修复等都是十分有意义的。因此,针对如何科学有效地对当前受污染地下水进行控制与修复的问题,深入探索研究垃圾填埋场地下水污染过程识别技术即污染羽各氧化还原特征区识别划分方法是十分必要的。结合当前国内外的研究进展,本课题从实际污染场地出发,基于垃圾渗滤液污染物在地下水环境中降解的生物地球化学作用以及氧化还原分区现象,研究一种基于敏感因子指数法的垃圾填埋场地下水污染过程识别技术。该技术通过确定敏感因子分别为溶解氧、亚硝酸盐、二价铁、硫化物以及二氧化碳、建立基于特征区表征的量化方法、计算各敏感因子权重值以及对各特征区值进行统计划分,最终实现对垃圾填埋场氧化还原特征区的识别;其中,确定敏感因子权重值也是整个技术体系中一个重要环节。在前期研究的基础上,本次研究将层次分析法、变异系数法以及组合权重法这三种不同的权重计算方法应用于敏感因子指数法中,并以北方某垃圾填埋场为例进行验证分析;最后构建出一种基于敏感因子指数法的垃圾填埋场地下水污染过程识别技术。研究结果表明:北方某垃圾填埋场地下水污染羽中确实存在氧化还原分区现象,该场地共识别出了五个氧化还原特征区,包括产甲烷区、硫酸盐还原区、铁还原区、硝酸盐还原区和氧还原区;组合权重法能够科学、客观、准确地确定各敏感因子的权重,相较另两种主、客观权重计算方法更适用于对垃圾填埋场地下水污染过程进行识别的敏感因子指数法;研究区中各氧化还原特征区分布并不完全依照微生物利用最终电子受体能力依次排列,其中某些小块区域可能由于其特殊水文地质条件或周边环境影响等一些原因导致实际分布与理论相较会有所偏差。从总体来看,识别结果是比较科学合理的,特征区分布情况与场地实际情况也较为吻合。
[Abstract]:The leakage of landfill leachate has caused more and more serious pollution to the surrounding water and soil environment, which has become a worldwide environmental problem, and its production mainly comes from the municipal solid waste sanitary landfill. Because landfill leachate is a kind of sewage with very complicated composition, it seeps into the water body and causes serious pollution to groundwater, which seriously threatens the safe use of groundwater. Landfill leachate leakage into the underground aquifer will form different redox zones. From the viewpoint of thermodynamics and biogeochemistry, methanogenic zones are first formed at the nearest location to the contaminated site. Then, with the increase of distance, sulfate reduction zone, iron reduction zone, manganese reduction zone, nitrate reduction zone and oxygen reduction zone were formed in turn. The appearance of these different redox environments is of great significance for the study of the degradation of pollutants in aquifers and the control and remediation of groundwater pollution. Therefore, in order to solve the problem of how to control and restore the contaminated groundwater scientifically and effectively, It is very necessary to study the identification technology of groundwater pollution process in landfills, I. e., the identification and partition method of each redox characteristic area of the pollution plume. Combined with the current research progress at home and abroad, this project is based on the biogeochemical effect of landfill leachate pollutants degradation in groundwater environment and the phenomenon of redox zoning. A process identification technique for groundwater pollution in landfills based on sensitive factor index method is studied. By determining that the sensitive factors are dissolved oxygen, nitrite, iron divalent, sulfides and carbon dioxide respectively, the technique establishes a quantitative method based on the characterization of characteristic regions, calculates the weight values of each sensitive factor and statistically divides the values of each characteristic region. Finally, the recognition of the redox characteristic region of the landfill site is realized, and the determination of the weight of the sensitive factor is also an important link in the whole technology system. On the basis of the previous research, this study applies the analytic hierarchy process (AHP), the variation coefficient method and the combined weight method to the sensitive factor index method, and takes a landfill site in the north as an example to verify and analyze. Finally, a process identification technique of groundwater pollution in landfill is constructed based on sensitive factor index method. The results show that redox zonation exists in groundwater pollution plume of a landfill in the north of China. Five redox characteristic areas have been identified in the site, including methanogenic zone, sulfate reduction zone, iron reduction zone, and so on. The combined weight method can scientifically, objectively and accurately determine the weight of each sensitive factor, compared with the other two main factors. The objective weight calculation method is more suitable for the sensitive factor index method to identify the groundwater pollution process in landfills, and the distribution of the redox characteristic regions in the study area is not arranged according to the ability of microorganism to utilize the final electron receptor. Some small areas may be deviated from the theory because of their special hydrogeological conditions or the influence of the surrounding environment. On the whole, the result of identification is more scientific and reasonable, and the distribution of the characteristic area is in good agreement with the actual situation of the site.
【学位授予单位】：东华理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X523;X705

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