基于稳定性同位素技术的人工湿地水力学特性研究

发布时间：2017-12-27 15:44

本文关键词：基于稳定性同位素技术的人工湿地水力学特性研究　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：人工湿地是近年迅速发展的污水处理技术,具有成本低、易管理、效果好等优点,人工湿地去除污染物的机理复杂,涉及物理、化学、微生物以及水生植物等作用,湿地内水流的流动状态和水力学特性具有多样性,存在一定的滞流和短流现象,降低了人工湿地的利用效率,影响水质处理效果。因此,探查湿地中各区域水流流动的趋势,最大化的减小湿地内部滞流区、短流区,有利于提升人工湿地利用效率,可为其合理运行提供理论依据,对于保证其发挥去污净化功能、延长运行寿命有重要意义。现有水流流态探测技术主要集中于示踪剂的表征技术、模型模拟技术以及基于ADV流速仪的实地探测技术。示踪剂的应用容易造成二次污染且在规模化湿地中运用成本较高,模型模拟技术多采用经验性参数,时效性较差,以上两种技术多集中于过程量参数的模拟,湿地内部流态的实时变化难以得出;基于ADV流速仪的实地探测技术需用到昂贵的流速仪,且测量过程十分耗费精力与体力。氢氧同位素示踪技术以湿地内部污水为分析对象,基于水体的蒸发过程中饱和蒸汽压与分子量成反比这一规律,重同位素D和18O在液相中不同程度的富集,区域停留时间越长,重同位素丰度越高,因此可通过同位素丰度分布确定内部流态。该技术具有无二次污染、实时反映湿地内部水流流态以及成本低的优势。本研究以小湄河人工湿地为研究对象,对其展开年度同位素调查,根据调查结果确定小湄河人工湿地滞流区、短流区的分布位置,确定湿地内部水流流态,同时布点监测湿地内部水流流速,确定流速分布状态,对水同位素示踪技术确定流态的适用性进行讨论;基于氢氧同位素示踪技术,对赵牛河人工湿地、徒骇河人工湿地进行流态表征,对流态影响因素进行分析。同时,对湿地内部水质分布特性展开研究,确定流态对水质分布的影响,主要得出以下结论:研究结果表明,三处研究对象δD和δ18O组成均低于中国东部大气降水线,小湄河人工湿地δD和δ18O的线性关系为:δD=6.67δ18O-5.87(R2=0.86),水同位素在小区域人工湿地中仍有区域性差异,这种差异主要由区域累积蒸发量的不同导致,其根本原因为区域停留时间存在差异;小湄河四季同位素δ180分布图能明显表征出内部滞流区的位置以及大小,冬季短流区的表征由于蒸发量较小而误差相对较大,其余三个季节均能表征区域内部短流区位置,且滞流区与短流区位置与流速表征结果一致,稳定性同位素技术对于人工湿地流态的表征具有可行性。赵牛河人工湿地δ D和δ 18O的线性关系为:δD=6.45δ18O-9.3(R2=0.89),徒骇河人工湿地δ D和δ 18O的线性关系为:δ D=4.38 δ 18O-26.63(R2=0.81),蒸发均对两处湿地水同位素组成产生了明显影响。水力流态分析结果表明,侧向式以及"T"型进水形式容易导致进水区域短流以及滞流现象发生,弯角处凹侧区域、人工岛后方容易形成滞流区,在河道横断面若植物密度、植物种类不同,容易造成区域水流阻力异化,阻力高的一侧易形成滞流区,阻力小的一侧易出现短流现象。氨氮在湿地中的分布呈现明显的滞流区浓度低、水流流畅区沿着进水口至出水口由高至低分布的现象,滞流区内由于水力交换作用较弱,高浓度氨氮无法流入滞流区,造成湿地面积利用率的下降;在植物生长的季节,总磷的分布与氨氮相近,其他季节总磷的分布容易受到底泥以及腐烂植物释放的影响而出现内部总磷浓度升高的现象。
[Abstract]:Artificial wetland wastewater treatment technology developed rapidly in recent years, has the advantages of low cost, easy management, good effect, mechanism of pollutants removal in constructed wetland complex, involving physics, chemistry, microorganism and aquatic plants, flow and hydraulic characteristics of water flow in the wetland has diversity, there is a certain stagnation and short flow the phenomenon, reduces the utilization efficiency of artificial wetlands, affecting the water treatment effect. Therefore, the water flow in the wetland area exploration trend, reduce internal wetland area, short flow stagnation zone, is conducive to enhancing the utilization efficiency of artificial wetlands, can provide a theoretical basis for its rational operation, to ensure the function of purifying, decontamination is of great significance to extend the operational life. Current flow detection techniques are mainly focused on the characterization of tracer, model simulation and field detection based on the ADV flow meter. The tracer is easy to cause two pollution and the use of high cost in large-scale wetland, model simulation technology using empirical parameters, poor timeliness, simulation of the above two kinds of technology focused on the process parameters, the real-time changes of the wetland is difficult to obtain the internal flow; flow meter expensive to the field detection technology with ADV velocity meter based on the measurement process and is a waste of energy and strength. Hydrogen and oxygen isotope tracer technology to wetland sewage as the analysis object, the evaporation process of water saturated vapor pressure and molecular weight based on the law of inverse D and 18O, the heavy isotopes in liquid phase enrichment area in different degree, longer residence time of heavy isotope abundance is high, it can determine the isotopic abundance distribution of internal flow. The technology has the advantages of no two pollution, the real-time reflection of the flow pattern in the wetland and the low cost. In this study, small Mei River wetland as the research object, annual isotope on the investigation, according to the distribution location of small Mei River wetland area, the survey results of short flow stagnation zone, determine the wetland internal flow pattern, at the same time monitored wetland internal flow velocity, determine the velocity distribution state of water isotope tracer technique to determine application of flow; hydrogen and oxygen isotope tracer technique based on the characterization of the flow of Zhao Niuhe artificial wetland, Tuhai River wetland, analyze the influence factors on the flow pattern. At the same time, to investigate the characteristics of distribution of wetland water quality, determine the flow pattern of the influence of water distribution, the main draw the following conclusions: the results showed that three of delta D and delta 18O were lower than the atmospheric water line in eastern China, linear relationship between the small river wetland Mekong Delta D and delta delta delta 18O: D=6.67 18O-5.87 (R2=0.86), there is still water isotope regional differences in area of artificial wetlands, this difference mainly by regional cumulative evaporation due to the different, the fundamental reason for the regional differences in residence time; small Mei River Delta 180 seasons isotope distribution map clearly showed the internal stagnation zone of the position and size, short in winter characterization of the flow area due to the evaporation of small and the error is relatively large, the remaining three seasons can characterize the regional internal short flow region location and stagnation zone and location of short flow area and flow velocity characterization results, stable isotope It is feasible to characterize the flow patterns of constructed wetlands. The linear relationship between the Niuhe Zhao artificial wetland Delta D and delta 18O, Delta D=6.45 Delta 18O-9.3 (R2=0.89), the linear relationship between the Tuhai River Wetland Delta D and delta 18O, Delta D=4.38, Delta 18O-26.63 (R2=0.81) have obvious influence on evaporation of two wetland water isotopic composition. Hydraulic flow analysis results show that the lateral and the "T" type water inlet area form easily lead to the occurrence of short flow and stagnation phenomenon, at the corner of the concave side area, easy to form artificial island behind the stagnation zone, in the river cross-section if plant species density, different plants, easy to cause the regional water resistance high resistance to alienation, side the formation of stagnation zone, the side resistance is small easy to appear the phenomenon of short circuiting. The distribution of ammonia nitrogen in the wetland showed significantly lower concentration of stagnation zone and water flow area along the inlet to outlet from high to low, the distribution of the phenomenon, the stagnation region due to hydraulic exchange effect is weak, the high concentration of ammonia nitrogen can not flow into the stagnation region, resulting in a decline in the utilization rate of the wetland area; during the growing season, similar to the distribution of total phosphorus with ammonia nitrogen, total phosphorus distribution in other seasons are vulnerable to sediment and rotting plants and internal phosphorus concentration rise phenomenon.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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