人工回灌含水层微生物堵塞机理与控制技术研究
发布时间：2018-08-31 19:34
【摘要】：随着地表水资源缺乏和污染问题愈发严重,地下水作为重要的供水水源被大量开采,由此引发一系列严重的环境地质问题。与此同时,全球范围内暴雨事件频发导致洪涝灾害发生,大量地表径流为城市排水系统带来巨大的压力。含水层存储和再利用是一种地下水人工补给与再利用的技术,即通过各种人工入渗措施,把地表收集的水源补充到地下含水层使之成为可以利用的地下水资源。利用雨洪水人工补给含水层是解决地下水超采、实现水资源的地表和地下联合调度、优化水资源配置、提高水资源综合利用率的必经之路。然而,在人工回灌过程中产生的堵塞问题(尤其是微生物堵塞)一直是制约雨洪水人工回灌技术广泛应用的关键因素。本论文主要针对人工回灌过程中含水层的微生物堵塞机理与控制技术展开研究。在室内设计一维渗流试验,模拟人工回灌含水层的过程。着重分析含水介质中微生物的主要类型、群落结构特征及其微观形态。探讨回灌条件对细菌分泌物组成和含量的影响。重点分析渗流过程中含水介质上的细菌数量及其分泌的不同类型胞外聚合物(Extracellular polymetric substances, EPS)与含水介质渗透性的关系,明确不同渗流阶段导致含水介质渗透性降低的关键因素,进一步探讨含水层微生物堵塞机理。并在此基础上,以山东省青岛市大沽河下游咸水含水层的人工回灌工程为例,对该回灌工程中可能发生的含水层堵塞风险进行评估,提出针对该含水层微生物堵塞的预防和治理方法。通过研究得出了以下新的认识和结论：(1)渗流过程中,含水介质上微生物类型主要为好氧细菌和放线菌为主。群落中优势菌种主要为甲基杆菌属、紫色杆菌属、耶尔森菌属、葡萄球菌属以及食酸菌属。优势菌种的生理生化特性使其在含水介质的堵塞过程中发挥重要的作用。此外,微生物的生长主要集中于表层含水介质中,越靠近出水端,细菌数量越少。渗流初期,细菌为短杆状,随后数量增加,体积增大。渗流试验后期,含水介质表面覆盖一层致密的生物膜结构。(2)在试验模拟的渗流条件下,回灌水的碳、磷浓度、盐度和温度对含水介质中细菌分泌多糖、蛋白质和EPS含量的影响较大,而氮浓度对细菌代谢产物含量的影响相对较小。同时,回灌水中碳源浓度及其与磷源的交互作用对细菌分泌多糖和EPS,总量的影响极为显著。(3)在连续渗流过程中,含水介质的渗透性随时间和空间均呈现明显的非均质性。微生物堵塞程度随着渗流距离的增大逐渐减缓。从渗流时间上看,初期介质的渗透性变化不明显,随着渗流时问的延长,介质的渗透性呈现快速下降趋势,微生物堵塞快速形成。而渗流后期,由于微生物堵塞已完全发生,介质渗透性的变化趋于平缓。(4)在连续渗流过程中,含水介质中的细菌依次经历适应期、对数生长期以及衰亡期,细菌数量呈现先上升后下降的趋势。与此同时,细菌分泌的松散结合型EPS (Loosely bound EPS, LB-EPS)和紧密结合型EPS (Tightly bound EPS, TB-EPS)含量均呈现先上升后略有下降的趋势。(5)不同渗流阶段引起含水介质渗透性下降的因素不同。其中,渗流初期(0-48 h)介质的相对渗透系数降低6%,归因于细菌数量的增多和体积的增大。渗流中期(48-14411),细菌与胞外聚合物的共同作用,致使介质渗透性的下降。而渗流后期(144-192 h),细菌数量和内层TB-EPS含量均呈现下降趋势,外层LB-EPS的增加是导致含水介质渗透性继续降低的关键因素。(6)利用贾疃坝、麻湾桥和小新河水源对大沽河下游咸水含水层进行人工回灌时,含水层可能发生的堵塞类型为物理堵塞和微生物堵塞。因此,回灌工程进行前,应对回灌水源采取适当的预处理措施,降低含水层物理堵塞和微生物堵塞的风险。具体处理工艺为：雨洪水→微滤(MF)或超滤(UF)→反渗透膜(RO)→加氯消毒→脱氯。而一旦发生含水介质的堵塞现象,应采取更换介质、反冲洗以及间歇回灌的方法,解决含水层的堵塞问题。
[Abstract]:With the shortage and pollution of surface water resources becoming more and more serious, groundwater, as an important source of water supply, is exploited in large quantities, resulting in a series of serious environmental geological problems. Storage and reuse of groundwater is a technique of artificial recharge and reuse of groundwater, that is, by means of various artificial infiltration measures, the water collected from the surface is added to the underground aquifer to make it available as groundwater resources. However, the blockage problem (especially microbial blockage) in the process of artificial recharge has been the key factor restricting the wide application of artificial recharge technology of rainwater and flood. A one-dimensional seepage experiment was designed to simulate the process of artificial recharge of aquifer. The main types of microorganisms in aquifer, community structure and micro-morphology were analyzed. The effects of recharge conditions on the composition and content of bacterial secretions were discussed. The bacteria in aquifer during the process of percolation were emphatically analyzed. The relationship between the amount of EPS and the permeability of aquifer was studied. The key factors leading to the decrease of permeability of aquifer in different seepage stages were clarified. The mechanism of microbial blockage in aquifer was further discussed. On this basis, the lower reaches of Dagu River in Qingdao City, Shandong Province were taken as an example. Taking the artificial recharge project of saline aquifer as an example, the possible risk of aquifer blockage in the recharge project is evaluated, and the prevention and treatment methods for microbial blockage in the aquifer are proposed. The following new understandings and conclusions are drawn through the study: (1) During the seepage process, the microbial types in the aquifer are mainly aerobic bacteria. The dominant bacteria in the community are mainly methyl bacillus, purple bacillus, Yersinia, Staphylococcus and acidophilus. The physiological and biochemical characteristics of the dominant bacteria make them play an important role in the plugging process of water medium. In addition, the growth of microorganisms is mainly concentrated in the surface aquifer medium, and the closer they get to the surface aquifer. At the end of the seepage test, the surface of the aquifer was covered with a dense biofilm structure. (2) Under simulated seepage conditions, the concentration of carbon, phosphorus, salinity and temperature of the recharged water secreted polysaccharides, proteins and EPS from the bacteria in the aquifer. At the same time, the interaction between carbon source concentration and phosphorus source had a significant effect on the total amount of polysaccharide and EPS secreted by bacteria. (3) During the continuous seepage process, the permeability of water medium showed obvious heterogeneity with time and space. The degree of microbial blockage gradually slows down with the increase of seepage distance. Seen from the seepage time, the permeability of the medium does not change obviously in the initial stage. With the prolongation of seepage time, the permeability of the medium shows a rapid decline trend, and the microbial blockage forms rapidly. (4) During the continuous seepage process, the number of bacteria in the aquifer went through the adaptive stage, logarithmic growth stage and decay stage, and the number of bacteria increased first and then decreased. Meanwhile, the contents of Loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) secreted by bacteria were both present. The relative permeability of the medium decreased by 6% at the initial stage of seepage (0-48 h), which was attributed to the increase of the number and volume of bacteria. In the later period of seepage (144-192h), both bacterial quantity and TB-EPS content in the inner layer showed a downward trend, and the increase of LB-EPS in the outer layer was the key factor leading to the continuous decrease of permeability of aquifer. (6) When artificial recharge was carried out in the saline aquifer of the lower reaches of Dagu River by using Jiagu dam, Mawanqiao and Xiaoxinhe water sources, the aquifer might occur. The types of plugging are physical plugging and microbial plugging. Therefore, proper pretreatment measures should be taken to reduce the risk of physical plugging and microbial plugging of aquifers before the recharge project is carried out. The specific treatment process is: rainwater flood microfiltration (MF) or ultrafiltration (UF) reverse osmosis membrane (RO) chlorination disinfection dechlorination. In order to solve the plugging problem of aquifer, the methods of medium replacement, backwashing and intermittent recharge should be adopted.
【学位授予单位】：中国海洋大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P641.25
本文编号：2215956
[Abstract]:With the shortage and pollution of surface water resources becoming more and more serious, groundwater, as an important source of water supply, is exploited in large quantities, resulting in a series of serious environmental geological problems. Storage and reuse of groundwater is a technique of artificial recharge and reuse of groundwater, that is, by means of various artificial infiltration measures, the water collected from the surface is added to the underground aquifer to make it available as groundwater resources. However, the blockage problem (especially microbial blockage) in the process of artificial recharge has been the key factor restricting the wide application of artificial recharge technology of rainwater and flood. A one-dimensional seepage experiment was designed to simulate the process of artificial recharge of aquifer. The main types of microorganisms in aquifer, community structure and micro-morphology were analyzed. The effects of recharge conditions on the composition and content of bacterial secretions were discussed. The bacteria in aquifer during the process of percolation were emphatically analyzed. The relationship between the amount of EPS and the permeability of aquifer was studied. The key factors leading to the decrease of permeability of aquifer in different seepage stages were clarified. The mechanism of microbial blockage in aquifer was further discussed. On this basis, the lower reaches of Dagu River in Qingdao City, Shandong Province were taken as an example. Taking the artificial recharge project of saline aquifer as an example, the possible risk of aquifer blockage in the recharge project is evaluated, and the prevention and treatment methods for microbial blockage in the aquifer are proposed. The following new understandings and conclusions are drawn through the study: (1) During the seepage process, the microbial types in the aquifer are mainly aerobic bacteria. The dominant bacteria in the community are mainly methyl bacillus, purple bacillus, Yersinia, Staphylococcus and acidophilus. The physiological and biochemical characteristics of the dominant bacteria make them play an important role in the plugging process of water medium. In addition, the growth of microorganisms is mainly concentrated in the surface aquifer medium, and the closer they get to the surface aquifer. At the end of the seepage test, the surface of the aquifer was covered with a dense biofilm structure. (2) Under simulated seepage conditions, the concentration of carbon, phosphorus, salinity and temperature of the recharged water secreted polysaccharides, proteins and EPS from the bacteria in the aquifer. At the same time, the interaction between carbon source concentration and phosphorus source had a significant effect on the total amount of polysaccharide and EPS secreted by bacteria. (3) During the continuous seepage process, the permeability of water medium showed obvious heterogeneity with time and space. The degree of microbial blockage gradually slows down with the increase of seepage distance. Seen from the seepage time, the permeability of the medium does not change obviously in the initial stage. With the prolongation of seepage time, the permeability of the medium shows a rapid decline trend, and the microbial blockage forms rapidly. (4) During the continuous seepage process, the number of bacteria in the aquifer went through the adaptive stage, logarithmic growth stage and decay stage, and the number of bacteria increased first and then decreased. Meanwhile, the contents of Loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) secreted by bacteria were both present. The relative permeability of the medium decreased by 6% at the initial stage of seepage (0-48 h), which was attributed to the increase of the number and volume of bacteria. In the later period of seepage (144-192h), both bacterial quantity and TB-EPS content in the inner layer showed a downward trend, and the increase of LB-EPS in the outer layer was the key factor leading to the continuous decrease of permeability of aquifer. (6) When artificial recharge was carried out in the saline aquifer of the lower reaches of Dagu River by using Jiagu dam, Mawanqiao and Xiaoxinhe water sources, the aquifer might occur. The types of plugging are physical plugging and microbial plugging. Therefore, proper pretreatment measures should be taken to reduce the risk of physical plugging and microbial plugging of aquifers before the recharge project is carried out. The specific treatment process is: rainwater flood microfiltration (MF) or ultrafiltration (UF) reverse osmosis membrane (RO) chlorination disinfection dechlorination. In order to solve the plugging problem of aquifer, the methods of medium replacement, backwashing and intermittent recharge should be adopted.
【学位授予单位】：中国海洋大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P641.25
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