垂直流人工湿地水力学规律与数学模型研究.pdf.doc.doc
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1、 华中科技大学博士学位论文垂直流人工湿地水力学规律与数学模型研究姓名:芦秀青申请学位级别:博士专业:市政工程指导教师:沈韫芬;陶涛2010-05-31 华中科技大学博士学位论文不均匀使得水流出现短流,湿地上部有效空间不能充分发挥。因此在保证处理效果的前提下,提高布水均匀性,可适当提高系统的水力负荷率。在反应器流动特性模型和污染物去除一级动力学模型研究方面:采用若干串联的完全混合反应器模型对间歇进水垂直流人工湿地的停留时间分布曲线进行了拟合,揭示了间歇进水垂直流人工湿地的流动特性类似于 3个串联的完全混合反应器水流特点。建立在理想推流反应器或 3个串联的完全混合反应器基础上的污染物降解一级动力学
2、模型可以模拟间歇进水 VFCW系统有机物、氨氮和总氮去除效果,得出了有机物、氨氮、总氮的一级反应速率常数和背景浓度值以及一级反应速率常数温度修正系数。在二维动态水力学模拟方面:采用地下水模拟软件 HYDROUS-2D对间歇进水垂直流人工湿地不同工况下出水流量、出水累计流量和停留时间分布进行了模拟,提出了适用于模拟石英砂为填充基质的垂直流人工湿地系统的水力学参数值,为垂直流人工湿地的水力学模型深入研究提供了基础的经验数据,为人工湿地对污染物去除机理模型提供了水力学模拟平台。在污染物降解机理模型研究方面:以二维动态水力学模型为基础,借鉴活性污泥模型、两步硝化模型提出了能够描述垂直流人工湿地多组分污
3、染物迁移转化的简单机理模型。通过与实际监测数据的对比,验证了该机理模型对实验系统有机物、氮污染物、无机磷去除效果模拟的有效性和各组分在湿地系统内动态规律变化。通过以上研究,加强了间歇进水垂直流人工湿地内部水流规律的认识,提供了垂直流人工湿地系统优化设计和优化运行的理论、技术支持以及实践经验,加深了人工湿地内部过程和机理的理解和洞察,促进人工湿地数学模型的发展,为人工湿地进一步的研究提供新的思路和方法,为人们解决与其相关的其它课题提供经验和依据,从而推动这一高效、低耗、生态技术的广泛应用。关键词:垂直流人工湿地间歇进水水力学停留时间分布数学模型污染物机理II 华中科技大学博士学位论文Abstra
4、ctConstructed wetlands (CWs) for wastewater treatment with the advantages ofsimpleness of equipment, low cost of construction, operation and maintance have beenthrived at 1970s. Especially vertical subsurface flow constructed wetlands (VFCWs) withintermittent feeding are increasingly used during the
5、 last several years due to their goodefficiency regarding the removal of nitrogen. However, there is a lack of understanding indetail about the transformation and elimination processes of pollutants in CWs. Most oftheir design and operation are still based on rules of thumb, lead to a quite differen
6、tremoval effect or unsuccesful use and result in discouraging the development andapplication of CWs.Aims to VFCW with intermittent feeding, some studies were conducteded. Firstly, toinvestigate the hydraulic behaviors on use of modified residence time distribution (RTD)theory and hydraulic efficienc
7、y and to discuss the potential effects hydraulic condition hason polltants removal. Secondly, to determine the flow pattern and the regularity of wetlandpollutant reduction by reproducing the experimental RTD and first-order removal kineticsmodels utilizing reaction theory and to present first order
8、 removal rate constants. Thirdly,to simulate dynamic hydraulic behaviors of pilot-scale VFCW employed thetwo-dimensional hydraulic simulation program HYDROUS-2D. Fourthly, to develop asimplified biological model based on HYDROUS-2D and activated sludge models (ASMs)and to be calibrated with a pilot-
9、scale vertical flow constructed wetland.In the case of study on hydraulic behaviour and the effects of hydraulic conditions oncontaminant removal efficiency of VFCWs with intermittent feeding, the influences ofplants and feeding strategies on hydraulic behaviors of VFCW are discussed and theimpacts
10、on polltants removal efficiency with all sorts of hydraulic operations includinghydraulic loading, residence time, flow rate, feeding interval and water distribution areexplored. Results indicate that plants have less influence on effluent rate and RTD, but issomewhat helpful to improve hydraulic ef
11、ficiency. Higher flow rate under the same dailyhydraulic loading and feeding interval or less feeding interval but the same daily hydraulicloading and the flow rate can increase effective volume ratio, improve hydraulicIII 华中科技大学博士学位论文performance and advance wetland removal efficiency of chemical ox
12、ygen demand(CODcr), annonium-nitrogen (NH4-N), total nitrogen (TN). Hydraulic efficiencycompared between continuous and intermittent feeding has no distinctively differencewhen the same flow rate was employed. Otherwise intermittent feeding can obtain higherflow rate under the same hydraulic loading
13、 to improve hydraulic perfermace or can obtainlower daily hydraulic loading under the same flow rate compared with continuous feedingto guarantee enough residence time which increases pollutans removal. Uniformly waterdistribution can promote the upper areas of VFCW are untilized to increase hydraul
14、icloading in case of the pollutants removal performance.In the case of the study on flow pattern and first-order removal kinetics models, thetanks in series (TIS) model, TIS with delay model and shiffted lognormal distributionmodel were employed to reproducing the experimental RTD. All proved capabl
15、e of fittingthe RTD curves and the flow pattern of VFCW can be presumed as flow characteries ofthree continuous stired tank reactors (CSTR). Furthermore, first-order removal kineticsmodels were conducted to simulate the reduction of CODcr, NH4-N, TN and the firstorder removal rate constants, backgro
16、und concentrations and temperature correctioncoefficient of VFCW with intermittent feeding are all presented.In the case of the study on the two-dimensional dynamic hydraulic simulation,effluent rate, cumulatived effluent and tracer experiments of VFCW with intermittentfeeding are simulated using si
17、mulation program HYDROUS-2D for flow and transport insaturated and unsaturated zones. Hydraulic parameters and soil parameters of VFCW withthe main substrate consists of quartz sand are calibrated. The simulated results show agood match with measured data. Moreover, the valuable experience with the
18、in-depthstudy on hydraulic numerical model of CWs are gained and the platform to propose abiological model of VFCW is provided.In the case of the study on mechanistic model of VFCW, a simple biological modellearned from CW2D model, ASMs and a two-step nitrification (ASM3_2N) model for theprocess nit
19、rification and denitrification on both nitrite and nitrate is proposed based on thetwo-dimensional dynamic hydraulic model, which can describe the multi-componentreactive transport. By comparing with the measured data, the model is available tosimulate the effect of COD, NH4-N and TP removal and dyn
20、amic changes of dissolvedIV 华中科技大学博士学位论文oxygen (DO), heterotrophic organisms, autotrophic organisms (nitrosomonas andnitrobacter), ornanic carbon compounds, NH4-N, nitrite-N (NO2-N), nitrate-N (NO3-N),inorganic phosphorus (IP) in VFCW.All the studies above enhance knowledge of hydraulic behaviors of
21、 VFCW withintermittent feeding to offer a support of theories and technologies and practicalexperiences on optimal design and optimal operation of VFCW, to increase understandingand insight of process and mechanisms in CW, and to prompote the development ofmathematical models of CW which advance the
22、 widespread use of the ecological tenology.Key words: Vertical subsurface flow constructed wetlandsIntermittent feedingMathematical modelHydraulicPollutantResidence time distributionMechanismV 独创性声明本人声明所呈交的学位论文是我个人在导师指导下进行的研究工作及取得的研究成果。尽我所知,除文中已经标明引用的内容外,本论文不包含任何其他个人或集体已经发表或撰写过的研究成果。对本文的研究做出贡献的个人和集体
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