曝气造流对城市黑臭河道内源氮营养盐行为的影响效应及其机制研究

发布时间：2018-01-15 06:07

本文关键词：曝气造流对城市黑臭河道内源氮营养盐行为的影响效应及其机制研究　出处：《华东师范大学》2017年博士论文　论文类型：学位论文

【摘要】：近年来城市河道中出现的黑臭现象成为亟待解决的环境污染和生态失衡问题。当外源污染逐步得到有效阻控后,黑臭河道底泥中内源污染物释放造成的二次污染越来越得到人们的重视。其中,氮营养盐释放是城市黑臭河道治理过程中的主要污染源,曝气造流作为黑臭河道治理中一种常用的原位修复措施,对底质环境及底泥中营养盐的迁移转化有重要影响。本论文依托国家重大科技专项"城市黑臭河道外源阻断、工程修复与原位多级生态净化关键技术研究与示范"(2009ZX07317-006)和国家自然科学基金"城市黑臭河道泥水界面硝化-反硝化对曝气扰动的响应机制"(41101471),以上海市工业河和温州市山下河为研究对象,在现场调研的基础上先后开展了底泥曝气造流原位修复小试和中试研究,系统分析了不同曝气造流条件下底泥内源氮营养盐行为特征,并结合实测流速通过Surfer软件和CFD(Computational Fluid Dynamics)方法模拟分析了曝气造流对应的流场及流态特征,探讨其相关的内在联系,同时采用 DGGE(Denatured Gradient Gel Electrophoresis)方法分析了曝气造流条件下浮泥层和黑泥层主要微生物优势菌群的响应特征,在以上研究基础上,开展了上海市工业河和温州市山下河治理示范工程曝气造流对底泥原位修复效果研究。主要研究结论如下:(1)不同曝气造流条件下模拟装置呈现湍流状态。其中,小试装置各工况平均流速依次为245 mm/s,291 mm/s,314 mm/s和358 mm/s,相应雷诺数为1101,1528,1761和1525;中试装置曝气机叶轮转速依次为350 rpm,230 rpm,160 rpm和290 rpm,分别对应工况运行平均流速为277 mm/s,181 mm/s,133 mm/s和225 mm/s,相应工况雷诺数依次为2272,1625,1315和1481。(2)通过结合实测值和模拟结果,X轴向流态在小试装置中靠近两端曝气机断面紊动更剧烈,而中试装置沿水流方向逐渐平缓;小试和中试装置Z轴向断面流态在泥水界面处流态最为剧烈。表明曝气造流促进底泥内源氮释放,各工况流场特征与流速和雷诺数两个水力学参数具较好一致性,因此分析认为流速和雷诺数可作为有效表征曝气造流的定量参数。(3)曝气造流条件下,小试装置充氧效率主要与流速相关,各工况运行稳定时的DO(Dissolved Oxygen)浓度与流速成线性关系。而中试装置充氧效率高于小试装置,其运行稳定时DO浓度接近相应水温条件下饱和DO水平。曝气造流下SOD(Sediment Oxygen Demand)在流速350mm/s以内时与流速成线性关系。中试装置内源总负荷相对较高导致SOD值小于小试装置。(4)曝气造流促进了上覆水硝化反应进行,氨氮转化为亚硝氮和硝氮,并扩散进入浮泥层。上覆水氨氮削减雷诺数1528-1761时与运行稳定时DO浓度和流速相关,在雷诺数在2232-2479时,氨氮削减与SOD及雷诺数正相关。浮泥层氨氮、硝氮及上覆水硝氮变化也与雷诺数和SOD正相关,紊动影响了 DO传质效率和浮泥层氨氮释放量;黑泥层氮营养盐行为主要与浓度差形成的扩散相关。总的来说,在一定流速范围(303mm/s-320mm/s)内雷诺数与硝化率正相关。(5)反硝化作用强度在一定流速区间内与雷诺数和SOD正相关。小试装置反硝化率最高对应流速区间为291 mm/s-314mm/s,雷诺数为1528-1761,而中试装置中该流速区间为303 mm/s-320 mm/s,雷诺数为2232-2479。通过拟合各装置内各工况硝化-反硝化作用得到流速为285mm/s时,对应雷诺数为2099,反硝化率最高达到42.29%。(6)在小试装置中,底泥细菌和古菌优势类群与雷诺数、硝化率和反硝化率正相关。细菌多样性高于古菌。而在中试装置中,浮泥层参与硝化反应优势菌群在303 mm/s-320 mm/s流速区间多样性丰度较好,表明硝化反应主要发生在浮泥层。其中,氨氧化细菌(Ammonia Oxidizing Bacteria,AOB)优势类群亚硝化单胞菌与DO浓度和硝化率相关,亚硝化螺菌属与SOD,硝化率,流速和雷诺数正相关。氨氧化古菌(Ammonia Oxidizing Archaea,AOA)优势类群为奇古菌门和泉古菌门,前者和不可培养古菌与流速和雷诺数呈较好正相关性,后者与硝化率呈较好正相关性,曝气造流下,AOA多样性和丰富度高于AOB。亚硝酸盐氧化菌(Nitrite Oxidizing Bacteria,NOB)优势类群为硝化杆菌属,其在运行稳定时多样性和丰度下降说明亚硝氮转化为硝氮,硝化杆菌属主要与雷诺数和流速正相关。(7)曝气造流促进硝氮向浮泥层和黑泥层扩散,提高底泥的反硝化作用强度。反硝化细菌(Denitrifying Bacteria,DB)在采样点2黑泥层具有更好的多样性和丰度,并且黑泥层中DB在303 mm/s-320 mm/s流速区间多样性和丰度上升。DB优势类群Dechloromonas sp.主要与反硝化率,雷诺数和流速呈正相关。在流速为303 mm/s-320 mm/s时微生物优势类群演替明显,这与该区间硝化-反硝化性能最优一致。各优势菌群均主要与流速和雷诺数正相关。(8)基于以上模拟装置相关研究,在工业河和山下河开展了底泥曝气造流原位修复示范工程效应研究,结果表明采用间歇曝气造流运行提高了反硝化率,其中工业河平均流速为133.3mm/s,对应雷诺数为1840时,反硝化率达到43.6%±12.9%,而山下河曝气造流时平均流速为169.4mm/s,对应雷诺数为2308时,反硝化率提高到52.6%±5.9%。相关CFD计算结果表明,曝气机放置深度与排列方式较好的耦合了硝化反硝化作用,当平均流速和雷诺数越接近模拟研究最优值,反硝化率越好。
[Abstract]:The phenomenon of black odor river city in recent years has become an environmental pollution and ecological imbalance problems. When exogenous pollution has been effectively prevent and control, the source of pollution in river sediment released two times pollution caused by more and more attention. Among them, nitrogen nutrients release is the main pollution source of governance process city of black odor River in the aeration flow making black odor River governance as a common remediation measures on the migration of sediment environment and sediment nutrient transformation has important effect. This paper is based on the national science and technology major special "city of black odor River exogenous blocking, engineering repair and in situ multi-level ecological purification research and demonstration of key technologies" (2009ZX07317-006) and the National Natural Science Foundation of the "city of black odor river water interface of nitrification and denitrification of the aeration disturbance response mechanism" (41101471), Shanghai River Industrial City Wenzhou City, mountain and river as the research object, on the basis of the investigation and has launched a pilot study on flow sediment aeration made in laboratory and in situ remediation, made a systematic analysis of the different aeration flow characteristics of sediment nitrogen nutrient behavior conditions, combined with the measured flow velocity by Surfer software and CFD (Computational Fluid Dynamics) simulation the flow pattern and the analysis of characteristics of the aeration flow making corresponding methods, explore the inherent relationship of related, at the same time using DGGE (Denatured Gradient Gel Electrophoresis) method to analyze the flow condition of floating sludge layer made of aeration and response characteristics of black mud layer of dominant microorganism, on the basis of the above research, carried out the demonstration project of Shanghai river the industrial city river and Wenzhou mountain aeration research on in-situ sediment remediation effect making flow. The main conclusions are as follows: (1) under the condition of different aeration flow simulation device has made The turbulent state. Among them, the condition of pilot plant average flow rate were 245 mm/s, 291 mm/s, 314 mm/s and 358 mm/s, the corresponding Reynolds number is 110115281761 and 1525; pilot plant aeration machine impeller speed was 350 rpm, 230 rpm, 160 rpm and 290 rpm, respectively corresponding running average flow rate was 277 mm/s, 181 mm/s, 133 mm/s and 225 mm/s, corresponding Reynolds number were 227216251315 and 1481. (2) by combining the measured and simulated results, the axial flow in the X pilot plant near the ends of the aerator section of turbulence is more severe, and the device along the flow direction gradually smooth; test device of Z axial section flow in the mud the interface pattern was the most severe. That made the small and medium flow aeration to promote the nitrogen release from sediments in different conditions, the flow field characteristics and velocity and Reynolds number of hydraulic parameters with good consistency, so that velocity and the Reynolds number can be Quantitative parameters of flow for effective characterization of aeration. (3) made of aerated flow conditions, the pilot unit of oxygenation efficiency and flow rate, the operation stability of the DO (Dissolved Oxygen) is a linear relationship between the concentration and velocity. The pilot plant oxygenation efficiency is higher than the test device, the operation is stable when the concentration of DO close to the level of the corresponding saturated DO temperature. The aeration flow (Sediment Oxygen made SOD Demand) in a linear relationship with the flow velocity is less than 350mm/s. The total load test device of endogenous led to relatively high SOD value is less than the small scale device (4) to promote the flow of aeration made overlying water ammonia nitrogen nitrification, into nitrite and nitrate, and diffused into the mud layer. The Reynolds number of the overlying water ammonia cut 1528-1761 and stable DO concentration and flow velocity, Reynolds number in 2232-2479, SOD and ammonia nitrogen reduction and Reynolds number of mud layer ammonia are related, The nitrate nitrogen and the overlying water nitrate nitrogen changes with Reynolds number and SOD is related to the turbulent effects of DO mass transfer efficiency and mud layer ammonia release; black mud nitrogen nutrient behavior mainly and concentration difference formed by diffusion. In general, in a certain velocity range (303mm/s-320mm/s) of Nereno number and nitrification rate positive correlation. (5) the denitrification intensity in a certain range of velocity and Reynolds number and SOD positive correlation. The pilot unit of denitrification rate was the highest velocity corresponding to the interval 291 mm/s-314mm/s, Reynolds number is 1528-1761, and the test device in the velocity range of 303 mm/s-320 mm/s, Reynolds number 2232-2479. by fitting each device within the conditions of nitrification and denitrification velocity is 285mm/s, the corresponding Reynolds number is 2099, the denitrification rate of up to 42.29%. (6) in the pilot plant, sediment bacteria and archaea heterotic groups and Reynolds number, nitrification rate and denitrification rate of positive correlation . bacterial diversity than archaea. In the pilot plant, a floating sludge layer in the nitration reaction of dominant bacteria in 303 mm/s-320 mm/s velocity range of diversity was better, show that the nitration reaction mainly occurs in the mud layer. The ammonia oxidizing bacteria (Ammonia Oxidizing, Bacteria, AOB) dominant genera Nitrosomonas with the DO concentration and nitrification rate, nitrosospira and SOD, nitrification rate, velocity and Reynolds number are related. Ammonia oxidizing archaea (Ammonia Oxidizing, Archaea, AOA) the dominant groups of bacteria and Crenarchaeota Qigu door door, the former and uncultured Archaea and the velocity and the Reynolds number is in positive correlation, the latter with the nitrification rate showed a good positive correlation, aeration flow making, AOA diversity and richness of AOB. is higher than that of nitrite oxidizing bacteria (Nitrite Oxidizing Bacteria, NOB) is the dominant groups Nitrobacter, the operation is stable when the diversity and abundance of the decline Nitrite nitrogen into nitrate nitrogen, Nitrobacter and Reynolds number and flow velocity are related. (7) made of nitrate to promote aeration flow diffusion of mud layer and black mud layer, improve the denitrification intensity of sediment. The denitrifying bacteria (Denitrifying Bacteria, DB) in the 2 sampling points with black mud layer better diversity and abundance, and the black mud layer in DB 303 mm/s-320 mm/s in the velocity range of the diversity and abundance of dominant species of Dechloromonas sp..DB increased and denitrification rate was positively correlated with flow rate. The Reynolds number of the flow rate is 303 mm/s-320 mm/s when the dominant microbial succession obviously, this and the interval of nitrification and denitrification optimal performance. The dominant bacteria were mainly related to velocity and Reynolds number correlation. (8) above simulation device related research based on industrial River and Shanxia river sediment aeration flow making was carried out in situ remediation demonstration project research results show that the effect. Intermittent aeration made flow improves the denitrification rate, the industry average river flow rate was 133.3mm/s, corresponding to the Reynolds number is 1840, the denitrification rate of 43.6% + 12.9%, and the mountain river aeration made flow average velocity is 169.4mm/s, corresponding to the Reynolds number is 2308, the denitrification rate increased to 52.6% + 5.9%. CFD the calculation results show that the aeration machine placed the coupling depth and arrangement good nitrification denitrification, when the average velocity and the Reynolds number is close to the simulation of the optimal value, the denitrification rate of the better.

【学位授予单位】：华东师范大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X522

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