可渗透反应墙渗透性能变化分析与数值模拟及防治措施的研究

发布时间：2017-12-27 23:13

本文关键词：可渗透反应墙渗透性能变化分析与数值模拟及防治措施的研究　出处：《安徽工程大学》2015年硕士论文　论文类型：学位论文

【摘要】：矿山、矸石山及尾矿坝等周边地下水受酸性矿井水污染严重。原位治理地下水技术中可渗透反应墙具有处理效果好、安装施工方便、运行成本第等优点越来越受到中外学者及专家的肯定,可以针对不同的地下污染水质装填不同处理作用的活性介质,其中生物PRB具有高效、环保,价廉、无二次污染等优点受到广泛重视。但随之而来的堵塞使PRB不能长期有效地运行。本文根据堵塞机理在理论上将PRB系统分为三个区块(物化区、生化区、过滤区)分别进行理论分析、设计实验模拟各种堵塞导致的渗透性能的变化规律。(1)物化区是废水进入PRB系统经过的第一个床层,主要对进水进行预处理,提高酸性矿井废水(AMD)的pH值和吸附处理部分重金属离子,为生化区减轻负荷和对微生物的毒理性。所以物化区不仅要考虑填料释放碱度的持续性和对重金属的吸附,还要考虑渗透速率的变化情况。由实验结果可以看出：①通过比较以陶粒为主的1、2#柱和石灰石为主3、4#柱出水pH值的变化规律可以得出,石灰石在调节废水碱度上不如陶粒,可能是由于石灰石粒度过大导致与水接触不充分,不能充分溶碱；②根据pH值的变化规律,对6个柱子重金属离子去除率的综合分析可以看出,沸石、活性炭吸附易饱和,ZVI有更强更持久的去除重金属能力；③综合比较6个柱子渗透速率得出渗透速率变化与pH的调节幅度和对重金属的去除率正相关,物化区堵塞主要由重金属氢氧化物沉淀导致；④物化区柱体实验得出ZVI、陶粒、活性炭配比1：2：4(3#柱)是最优的,调节pH稳定、重金属去除率高且稳定、渗透速率下降幅度小且平缓,因此可以在实际应用中采用。(2)通过研究比较国内外几种典型的生物堵塞模型,选择了两种适合模拟生化区渗透速率变化的模型,即修正的微生物PRB堵塞耦合模型和Clement模型。分别设计室内柱体实验：填料介质为大陶粒(3-5mm)：小陶粒(13mm)：玉米芯体积比为1：1：1,接种10%的SRB菌种,控制流量为3mL/min,实验求解模型中的未知参数a、b、Km、 n,代入模型计算模拟值。结果表明：Clement模型能较准确模拟实验初期的渗透速率变化；而修正的微生物PRB堵塞耦合模型在实验后期拟合度较高,所以生化区渗透性能变化可以用两个模型共同来模拟。根据实测值发现,相对渗透速率随柱子加深逐渐增大,在距离进水口10cm处最小。实验共运行了18天,而介质相对渗透速率下降不明显,总体都保持在90%以上,所以说明生物堵塞是一个长期的过程,利用生物PRB原位治理地下水本身就是个经济有效持久的方法。(3)过滤区首先通过设计单因素实验筛选出对悬浊物过滤效果好且渗透速率下降最小的一组填料配比、进水悬浊物浓度、水力停留时间。最终得出陶粒：石英砂=2：1、进水悬浮物浓度为150mg/L、水力停留时间为15h为最佳实验条件。采用最佳实验条件重新设计柱体实验,运行了105个小时,每15h测量并计算相对渗透速率,结果发现过滤区的堵塞主要发生在表层和浅水层,距离填料表面10-20cm、20-30cm、30-40cm深度处相对渗透速率分别从1下降到0.65、0.74、0.90。所以过滤过程中大部分悬浊颗粒被表浅层介质截留吸附,按水流方向浓度逐渐减小。本章结合地下水渗流方程、悬浊物质量运移方程、悬浊物的吸附脱附方程,用多物理场软件COMSOL耦合求解,与实测值拟合效果较好,所以该一系列方程可以用来模拟过滤区堵塞过程。(4)通过借鉴国内外专家学者关于垃圾渗滤液回灌、尾矿坝等一系列成功的防治堵塞措施,并根据本文各分区实验得出适合各分区的一系列防治措施。其中,物化区根据其在PRB中的作用选择合适的介质种类、粒径和配比来预防堵塞的发生,用反冲洗法或超声波法来缓解床层内部堵塞,在运行一段时间后当填料释碱能力慢慢减弱且渗透速率减小时还可以更换填料；生化区堵塞的预防措施可以采用适当改变介质初始孔隙、初始接种菌量、进水有机营养物浓度,为了防止微生物数量泛滥,还可以采取间歇运行,保持床体干燥来抑制微生物的过度生长,而生化区堵塞可以设置清淤装置；过滤区可以选用合适的介质种类配比、粒径、调整进水水质和水流速度等措施来预防堵塞的发生,而过滤区堵塞主要发生在表层浅层,可以采用反冲洗法、定期更换部分介质等方法来治理堵塞。
[Abstract]:The surrounding ground water of mine, Gangue Mountain and tailings dam is polluted seriously by acid mine water. Osmotic reaction wall has good treatment effect, convenient installation and construction and operation cost of the advantages of more and more Chinese and foreign scholars and experts will be in situ groundwater treatment technology, the active medium for filling in different underground water pollution treatment effect, which PRB has the advantages of high efficiency, environmental protection, low cost, no two pollution etc. has received extensive attention. But the concomitant blockage makes it impossible for PRB to run effectively for a long time. Based on the blockage mechanism, the PRB system is divided into three blocks (materialized area, biochemical area and filter area). Theoretical analysis and design experiments are carried out to simulate the change rule of permeability caused by various plugging. (1) the physicochemical area is the first bed that the wastewater passes into the PRB system. It mainly pretreated the influent, increased the pH value of acid mine drainage (AMD) and adsorbed some heavy metal ions, which reduced the load and the toxicity of microorganisms to the biochemical area. Therefore, the physicochemical area should not only consider the continuity of the alkalinity of the packing and the adsorption of heavy metals, but also consider the change of the permeation rate. The experimental results show that: through the comparison with ceramsite based 1 2# column, and limestone as the main changes of the 3 4# column, the pH value of the effluent can be drawn, limestone in the regulation of wastewater alkalinity than ceramsite, probably due to excessive lead lime stone particle contact with water is not sufficient, not fully according to the change of alkali; the characteristic value pH, comprehensive analysis on the removal rate of the 6 pillars of heavy metal ions can be seen, zeolite, activated carbon adsorption saturation, ZVI has stronger and more persistent heavy metal removal ability; the comprehensive comparison of 6 pillars permeation rate through adjusting amplitude permeation rate with the change of pH and the heavy metal removal rate is related to. The area is mainly composed of heavy metal hydroxides leads to clogging; the physicochemical zone column experiment of ZVI, ceramic, activated carbon ratio 1:2:4 (3# column) is the optimal regulation of pH stability, the removal rate of heavy metal It can be used in practical application because of its high stability and low penetration rate. (2) by studying and comparing several typical models of biological clogging at home and abroad, two models suitable for simulating the change of osmotic rate in biochemical area were selected, that is modified microbial PRB clogging coupling model and Clement model. Indoor column experiments were designed respectively: packing medium was 3-5mm, 13mm: corncob volume ratio was 1:1:1, inoculated with 10% SRB strains, and control flow rate was 3mL/min. The unknown parameters of a, B, Km and N were solved in experiment. The results showed that the Clement model could accurately simulate the infiltration rate in the early stage of the experiment, while the modified microbial PRB clogging coupling model was higher in the later stage of the experiment, so the permeability change in the biochemical area could be simulated by two models. According to the measured values, the relative permeation rate increases with the depth of the column, and is the smallest at the distance to the 10cm. The experiment lasted for 18 days, and the relative permeability rate of the medium decreased less than 90%. Therefore, bioplugging is a long-term process. Using biological PRB to control groundwater in situ is an economic and effective method. (3) filter area first designed a single factor experiment to screen out a set of packing ratio, influent suspension concentration and hydraulic retention time. It is concluded that the best experimental conditions are quartz sand =2:1, concentration of water suspended substance 150mg/L, and hydraulic retention time of 15h. Re column designing experiment using the optimum experimental conditions, running 105 hours, each 15h measurement and calculation of relative permeability rate, it is found that the blocking filtration area mainly occurred in the surface and shallow layer distance, 10-20cm, 20-30cm, 30-40cm surface depth relative permeability rate decreased from 1 to 0.65, 0.74, 0.90. Therefore, most of the suspended particles in the filtration process are intercepted by the shallow layer medium, and gradually decrease according to the direction concentration of the flow. Combined with the groundwater seepage equation, the mass transport equation of suspended matter and the adsorption and desorption equation of suspended solids, this chapter solves the problem of blockage in the filtration area by using the multi physical field software COMSOL, and the fitting results are good with the measured values. (4) by drawing on a series of successful measures for prevention and control of leachate recirculation and tailings dam at home and abroad, a series of preventive measures for each sub area are obtained based on the experiments in different regions. Among them, the materialized area according to its role in PRB media type, choose appropriate particle size and ratio to prevent blockage, to alleviate the bed internal blockage by backwash method and ultrasonic method, after running for a period of time when the filler release capability of alkali slowly weakens and the penetration rate decreases when can also replace the packing biochemical; zone blocking preventive measures can be used to change the appropriate medium initial porosity, initial inocula and influent organic nutrient concentrations, in order to prevent the spread of microorganisms, can also be used in intermittent operation, keep the excessive growth of the bed body drying to inhibit microbial and biochemical zone blocking can set the dredging device; the filtering area ratio, can be selected medium type suitable particle size, adjust the water quality and water flow rate and other measures to prevent the occurrence of clogging, and filtration zone blocking occurs mainly in the shallow surface, can be used to counter The method of washing and replacing part of medium to control the clogging.
【学位授予单位】：安徽工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X523

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