地表水中硝态氮的去除及其与硫的相关性

发布时间：2018-07-05 02:11

本文选题：氢自养反硝化 + UBER反应器　；参考：《中国科学院烟台海岸带研究所》2017年博士论文

【摘要】：近年来,随着工农业的发展和人口的快速增长,水体中各类含氮化合物的含量急剧增加,其中绝大部分含氮化合物会在适宜的环境条件下转化为相对稳定的硝态氮。通常,由于高负荷含氮污废水直接输入等原因,地表水体中的碳氮比往往相对较低,同时由于自然水体相对较弱的自净能力,使得硝态氮在地表水体中不断累积,高浓度硝态氮已成为部分地区地表水最为突出的污染因子,其严重影响了地表水的资源价值,并危害人们的身体健康。因此,硝态氮的有效脱除已经成为当前水污染防治领域所面临的主要技术瓶颈之一。污染水体中去除硝酸氮的传统方法主要包括物理、化学、生物及其复合技术方法等,但这些方法均存在运行成本高,产生二次污染等缺陷。氢自养反硝化技术被认为是一种经济有效的硝态氮脱除技术,但传统的氢自养反硝化反应器存在电极与基质接触面较小、过水断面水流不均匀、阴极利用率低等不足。目前,国内外关于城市污水硝态氮脱除的研究进展迅速,但尚未发现专门用于地表水中硝态氮去除的成熟工艺。因此,识别硝态氮的来源及其形成过程,并据此研发针对地表水硝态氮去除的工艺对当前水处理领域的技术进步具有重要意义。本论文以胶东地区地表水体硝态氮高、碳氮比低及难以采用常规技术手段进行脱氮等水质问题为导向,在充分调研的基础上设计并优化了升流式三维电极氢自养反硝化反应器,实现了地表水硝态氮的高效去除,论文选题具有重要理论意义和实际应用价值,取得的主要研究成果如下:论文通过对入库流域输入、土壤地表径流及大气沉降等不同来源氮通量与总量的实测核算,同时结合15N稳定同位素示踪技术,对烟台门楼水库硝态氮的来源进行了准确识别和超标原因解析,同时发现:(1)库区水体氮素污染主要为硝态氮(占总氮比例90%),由于水体中DO值较高(3 mg/L),且碳氮比较低(1),反硝化脱氮作用较弱;(2)库区水体总氮来源主要为上游河流输入(沿岸畜禽养殖等污染排放)和周边土壤地表径流面源污染输入(化肥流失等);(3)门楼水库虽然对硝态氮去除有一定的自净能力,但自净脱氮率只有20%,因此需要适当的人工强化处理。本研究根据门楼水库流域等胶东地区地表水的水质特征,配置硝态氮浓度适宜的模拟水样,并在现有氢自养反硝化反应器的基础上对其主要构建和参数进行了改进和优化:(1)将传统的平流式电化学氢自养反硝化反应器改为升流式电化学反应器(UBER),从而增加其基质的利用率;(2)在氢自养反硝化反应器中添加碳粒,构建三维电极并提高电极与基质的接触面积,提高反应效率;(3)设置两个串联式UBER反应器,保障水力停留时间并增加其出水稳定性。系列实验研究发现,当电流强度为10 m A、水力停留时间(HRT)为6 h时,氢自养反硝化反应器对硝态氮的去除率最高(~95%)。经优化设计的新型氢自养反硝化反应器在较低温度(15℃)时就可实现较高的脱氮率(~90%),这对北方地区越冬期间开展高效脱氮工作具有重要的指导意义。然而,研究结果表明,该体系若在高浓度氨氮存在的条件下,氢自养反硝化反应器对硝态氮的去除效率会明显下降。为了实现对污染水体中硝态氮和铵态氮的同步去除,本研究又对上述氢自养反硝化反应器进行了进一步改进,在原UBER反应器的底部设置硝化区,将含有铵态氮和硝态氮的模拟废水先经过硝化区进行硝化后再进行氢自养反硝化,以实现同步硝化反硝化。研究结果表明:(1)改进的UBER系统能够实现同步硝化反硝化,且脱氮率较高(90%),其中耗氧区主要以异养反硝化为主,自养硝化区主要以氢自养反硝化为主;(2)生物膜溶解氧(DO)在异养硝化区和氢自养反硝化区的垂向分布分布表明,有氧和缺氧层在生物膜中共存,从而促进了高效脱氮。由于沿海地区地表水中通常含有一定量的硫酸盐,而硫酸盐还原过程可能会抑制硝酸盐的反硝化作用,因此本研究又对脱氮体系中的硫氮耦合作用进行了深入研究。为了探明硫对氢自养反硝化的影响机制,提高氢自养反硝化的脱氮效率,本研究主要通过调节进水S/N来观察其对氢自养反硝化脱氮的影响。研究结果表明:(1)在较低的S/N(1:2)下硫酸盐不会抑制氢自养反硝化反应器的脱氮效率,可以实现NO_3~--N与SO_4~2--S的同步脱除,硝态氮的去除率及硫酸盐的去除率均可达到80%左右;(2)随着S/N升高(1:1),硫酸盐还原产生的硫化物累积会对氢自养反硝化及硫酸盐还原本身产生抑制作用,其临界抑制浓度分别为10 mg/L和15 mg/L;(3)在较高的S/N下(2:1),较高的硫化物浓度和较低的pH均对氢自养反硝化产生抑制作用。因此,在对含一定浓度硫酸盐水体进行脱氮时,S/N也对脱氮效率有显著影响,较低的S/N有助于实现NO_3~--N与SO_4~(2-)-S的同步脱除。
[Abstract]:In recent years, with the development of industry and agriculture and the rapid growth of population, the content of various nitrogen compounds in the water body increases rapidly. Most of the nitrogen compounds will be converted to relatively stable nitrate nitrogen under suitable environment conditions. Usually, the carbon and nitrogen ratio in the surface water is compared to the direct input of high load nitrogen waste water. The higher concentration of nitrate nitrogen has become the most prominent pollution factor in surface water in some areas, which has seriously affected the resource value of surface water and endangers the health of people. Therefore, the effective removal of nitrate nitrogen has already been effectively removed. It has become one of the main technical bottlenecks in the field of water pollution prevention and control. The traditional methods of removing nitrate in polluted water mainly include physical, chemical, biological and composite techniques, but these methods have high operating costs and two pollution defects. Hydrogen autotrophic denitrification is considered as a kind of economy. The effective nitrate removal technology is effective, but the traditional hydrogen autotrophic denitrification reactor has smaller contact surface between the electrode and substrate, the water flow in the cross section is not uniform, and the utilization rate of the cathode is low. At present, the research progress on the removal of nitrate nitrogen in urban sewage is rapid, but the mature workers who have been used for the removal of nitrate nitrogen in the surface water have not been found yet. Therefore, it is of great significance to identify the source of nitrate nitrogen and its formation process, and to develop the technology for the removal of nitrate nitrogen in the surface water is of great significance to the technological progress in the field of water treatment. This paper is guided by the high nitrate nitrogen, low carbon and nitrogen ratio and the difficulty of nitrogen removal by conventional technology in the surface water of Jiaodong. On the basis of full investigation, the upflow three-dimensional electrode hydrogen autotrophic denitrification reactor was designed and optimized, which realized the efficient removal of nitrate nitrogen in the surface water. The thesis has important theoretical significance and practical application value. The main achievements of this thesis are as follows: the paper through the input of the sink basin, soil surface runoff and atmospheric settlement, etc. According to the measured calculation of nitrogen flux and total amount of different sources, and combined with 15N stable isotope tracing technique, the source of nitrate nitrogen in Yantai Mun Lou reservoir was accurately identified and the reasons for exceeding the standard were analyzed. At the same time, it was found that (1) nitrogen pollution in the water body of the reservoir area was mainly nitrate nitrogen (90% of total nitrogen), because of the higher value of DO (3 mg/L), and the ratio of carbon and nitrogen to the water body. Lower (1), denitrification and nitrogen removal is weak; (2) the main source of total nitrogen in the reservoir area is the input of the upstream river (coastal livestock and poultry breeding and other pollution emission) and the input of surface runoff source pollution in the surrounding soil (chemical fertilizer loss and so on). (3) although the reservoir has a certain self purification ability to remove nitrate nitrogen, the self purification rate of nitrogen removal is only 20%. Therefore, it needs to be suitable. According to the characteristics of the water quality of the surface water in Jiaodong area, such as the valley of the men's reservoir, the present study arranged the suitable simulated water samples with nitric nitrogen concentration, and on the basis of the existing hydrogen autotrophic denitrification reactor, the main construction and parameters were improved and optimized. (1) the conventional advection electrochemical hydrogen autotrophic denitrification reaction was carried out. To increase the utilization rate of the matrix, the stress is changed to the upflow electrochemical reactor (UBER). (2) adding carbon particles to the hydrogen autotrophic denitrification reactor, building a three-dimensional electrode and improving the contact area between the electrode and the matrix, and improving the reaction efficiency. (3) setting up two series UBER reactors to ensure the hydraulic retention time and increase the stability of the effluent. The experimental study found that when the current intensity is 10 m A and the hydraulic retention time (HRT) is 6 h, the hydrogen autotrophic denitrification reactor has the highest removal rate of nitrate nitrogen (~95%). The high denitrification rate (~90%) can be achieved at a lower temperature (15 degrees C) after the optimized design of a new type of hydrogen autotrophic denitrification reactor (15 degrees C), which will carry out high efficiency during the overwintering period in the northern region. The work of denitrification has important guiding significance. However, the results show that the efficiency of the removal of nitrate nitrogen in the autotrophic denitrification reactor of the hydrogen autotrophic denitrification reactor will be obviously reduced under the presence of high concentration ammonia nitrogen. In order to realize the removal of nitrate nitrogen and ammonium nitrogen in the polluted water, the autotrophic denitrification reaction of the above-mentioned hydrogen is also studied. The device was further improved, and the nitrification area was set at the bottom of the original UBER reactor. The simulated wastewater containing ammonium nitrogen and nitrate nitrogen was first nitrification and then nitrification and denitrification was carried out to achieve simultaneous nitrification and denitrification. The results showed that: (1) the improved UBER system can achieve simultaneous nitrification and denitrification and the rate of denitrification is higher. High (90%), mainly heterotrophic denitrification, and autotrophic denitrification mainly in the autotrophic nitrification area; (2) the distribution of dissolved oxygen (DO) in the heterotrophic nitrification and autotrophic denitrification areas shows that oxygen and anoxic layers are stored in the biofilm, thus promoting high efficiency denitrification. It is usually contained in a certain amount of sulphate, and the process of sulfate reduction may inhibit the denitrification of nitrate. Therefore, this study further studies the interaction of sulfur and nitrogen in the denitrification system. In order to explore the mechanism of the effect of sulfur on the autotrophic denitrification of hydrogen, the efficiency of the denitrification of hydrogen autotrophic denitrification is improved. This study is mainly through the regulation of this study. The effect of influent S/N on the denitrification of hydrogen autotrophic denitrification was observed. The results showed that (1) the removal efficiency of the hydrogen autotrophic denitrification reactor was not inhibited under the lower S/N (1:2), and the simultaneous removal of NO_3~--N and SO_4~2--S could be achieved. The removal rate of nitrate nitrogen and the removal rate of sulfate could reach about 80%; (2) with S/N liters High (1:1), sulphate accumulation produced by sulfate reduction could inhibit hydrogen autotrophic denitrification and sulfate reduction by 10 mg/L and 15 mg/L, respectively, (3) under higher S/N (2:1), higher sulphide concentration and lower pH for hydrogen autotrophic denitrification. S/N also has a significant effect on nitrogen removal efficiency when nitrogen removal is carried out in sulfate water. Lower S/N is helpful for simultaneous removal of NO_3~--N and SO_4~ (2-) -S.
【学位授予单位】：中国科学院烟台海岸带研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X52

【参考文献】