【摘要】：隨著地表水資源缺乏和污染問題愈發(fā)嚴(yán)重,地下水作為重要的供水水源被大量開采,由此引發(fā)一系列嚴(yán)重的環(huán)境地質(zhì)問題。與此同時,全球范圍內(nèi)暴雨事件頻發(fā)導(dǎo)致洪澇災(zāi)害發(fā)生,大量地表徑流為城市排水系統(tǒng)帶來巨大的壓力。含水層存儲和再利用是一種地下水人工補(bǔ)給與再利用的技術(shù),即通過各種人工入滲措施,把地表收集的水源補(bǔ)充到地下含水層使之成為可以利用的地下水資源。利用雨洪水人工補(bǔ)給含水層是解決地下水超采、實現(xiàn)水資源的地表和地下聯(lián)合調(diào)度、優(yōu)化水資源配置、提高水資源綜合利用率的必經(jīng)之路。然而,在人工回灌過程中產(chǎn)生的堵塞問題(尤其是微生物堵塞)一直是制約雨洪水人工回灌技術(shù)廣泛應(yīng)用的關(guān)鍵因素。本論文主要針對人工回灌過程中含水層的微生物堵塞機(jī)理與控制技術(shù)展開研究。在室內(nèi)設(shè)計一維滲流試驗,模擬人工回灌含水層的過程。著重分析含水介質(zhì)中微生物的主要類型、群落結(jié)構(gòu)特征及其微觀形態(tài)。探討回灌條件對細(xì)菌分泌物組成和含量的影響。重點分析滲流過程中含水介質(zhì)上的細(xì)菌數(shù)量及其分泌的不同類型胞外聚合物(Extracellular polymetric substances, EPS)與含水介質(zhì)滲透性的關(guān)系,明確不同滲流階段導(dǎo)致含水介質(zhì)滲透性降低的關(guān)鍵因素,進(jìn)一步探討含水層微生物堵塞機(jī)理。并在此基礎(chǔ)上,以山東省青島市大沽河下游咸水含水層的人工回灌工程為例,對該回灌工程中可能發(fā)生的含水層堵塞風(fēng)險進(jìn)行評估,提出針對該含水層微生物堵塞的預(yù)防和治理方法。通過研究得出了以下新的認(rèn)識和結(jié)論：(1)滲流過程中,含水介質(zhì)上微生物類型主要為好氧細(xì)菌和放線菌為主。群落中優(yōu)勢菌種主要為甲基桿菌屬、紫色桿菌屬、耶爾森菌屬、葡萄球菌屬以及食酸菌屬。優(yōu)勢菌種的生理生化特性使其在含水介質(zhì)的堵塞過程中發(fā)揮重要的作用。此外,微生物的生長主要集中于表層含水介質(zhì)中,越靠近出水端,細(xì)菌數(shù)量越少。滲流初期,細(xì)菌為短桿狀,隨后數(shù)量增加,體積增大。滲流試驗后期,含水介質(zhì)表面覆蓋一層致密的生物膜結(jié)構(gòu)。(2)在試驗?zāi)M的滲流條件下,回灌水的碳、磷濃度、鹽度和溫度對含水介質(zhì)中細(xì)菌分泌多糖、蛋白質(zhì)和EPS含量的影響較大,而氮濃度對細(xì)菌代謝產(chǎn)物含量的影響相對較小。同時,回灌水中碳源濃度及其與磷源的交互作用對細(xì)菌分泌多糖和EPS,總量的影響極為顯著。(3)在連續(xù)滲流過程中,含水介質(zhì)的滲透性隨時間和空間均呈現(xiàn)明顯的非均質(zhì)性。微生物堵塞程度隨著滲流距離的增大逐漸減緩。從滲流時間上看,初期介質(zhì)的滲透性變化不明顯,隨著滲流時問的延長,介質(zhì)的滲透性呈現(xiàn)快速下降趨勢,微生物堵塞快速形成。而滲流后期,由于微生物堵塞已完全發(fā)生,介質(zhì)滲透性的變化趨于平緩。(4)在連續(xù)滲流過程中,含水介質(zhì)中的細(xì)菌依次經(jīng)歷適應(yīng)期、對數(shù)生長期以及衰亡期,細(xì)菌數(shù)量呈現(xiàn)先上升后下降的趨勢。與此同時,細(xì)菌分泌的松散結(jié)合型EPS (Loosely bound EPS, LB-EPS)和緊密結(jié)合型EPS (Tightly bound EPS, TB-EPS)含量均呈現(xiàn)先上升后略有下降的趨勢。(5)不同滲流階段引起含水介質(zhì)滲透性下降的因素不同。其中,滲流初期(0-48 h)介質(zhì)的相對滲透系數(shù)降低6%,歸因于細(xì)菌數(shù)量的增多和體積的增大。滲流中期(48-14411),細(xì)菌與胞外聚合物的共同作用,致使介質(zhì)滲透性的下降。而滲流后期(144-192 h),細(xì)菌數(shù)量和內(nèi)層TB-EPS含量均呈現(xiàn)下降趨勢,外層LB-EPS的增加是導(dǎo)致含水介質(zhì)滲透性繼續(xù)降低的關(guān)鍵因素。(6)利用賈疃壩、麻灣橋和小新河水源對大沽河下游咸水含水層進(jìn)行人工回灌時,含水層可能發(fā)生的堵塞類型為物理堵塞和微生物堵塞。因此,回灌工程進(jìn)行前,應(yīng)對回灌水源采取適當(dāng)?shù)念A(yù)處理措施,降低含水層物理堵塞和微生物堵塞的風(fēng)險。具體處理工藝為：雨洪水→微濾(MF)或超濾(UF)→反滲透膜(RO)→加氯消毒→脫氯。而一旦發(fā)生含水介質(zhì)的堵塞現(xiàn)象,應(yīng)采取更換介質(zhì)、反沖洗以及間歇回灌的方法,解決含水層的堵塞問題。
[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.
【學(xué)位授予單位】：中國海洋大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：P641.25

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本文編號：2215956