电解强化人工湿地脱氮除磷过程与机理研究
发布时间：2018-09-14 09:19
【摘要】：本文基于电化学反应稳定高效的特点,开展了电化学与人工湿地联合脱氮除磷过程与机理研究。构建电解-生物滤床\人工湿地室内小试装置,研究不同人工湿地基质、电极布置方式、电解时间、电流密度、水力停留时间(Hydraulic retention time,HRT)等电解设备和工艺参数对硝态氮(NO_3~--N)和磷酸盐-磷(PO_4~(3-)-P)去除效果的影响,并分析电解对湿地植物和基质生物膜细菌群落结构的影响。开发了一种新型的光伏电解人工湿地技术,应用于污水处理厂尾水的深度净化处理。获得的主要结论如下：电解-生物滤床(Electrolysis-integrated biofilter, E-BF)将电解引入生物滤床处理工艺中,E-BF以沸石作为基质,有利于模拟废水中氨氮(NH_~(3-)-N)的去除；铁电极作为电解反应的阳极,电解后产生Fe~(2+), Fe~(2+)进一步氧化成Fe~(3+), Fe~(3+)与水体中OH-生成Fe(OH)_3絮凝剂,铁离子与磷酸盐的化学反应以及Fe(OH)_3的絮凝沉淀作用有利于PO_4~(3-)-P的去除。基质吸附的氨氮在微生物作用下转化为亚硝态氮(NO_2~--N)和NO_3~--N, E-BF中N02-N和NO_3~--N的积累较对照组(Biofilter, BF)少。在不同的电解条件和PO_4~(3-)-P的进水浓度下,去除PO43--P的最低电耗为1.1kW·h/g。16S rDNA测序结果表明E-BF基质中有一定含量的铁硫细菌,在铁的生物化学转化过程中发生作用。电解-水平潜流人工湿地(Electrolysis-integrated horizontal subsurface-flow constructed wetland system, E-HFCWs)处理模拟废水的研究结果表明电极的布置方式会影响氮磷去除效果,采用双阴极的电极布置方式有利于NO_3~--N和PO43--P的去除；最适宜的电流密度、电解时间和HRT分别为0.07mA/cm2、8h和8h；同时电解会导致电极周围的湿地床体形成一个相对碱性的、温度略高和氧化还原电位(Oxidation-reduction potential, ORP)较低的微环境,有利于NH_3~--N和NO_3~--N的同步微生物转化；对不同HRT条件下E-HFCWs对氮磷去除电耗结果分析表明：去除单位总氮最低电耗为0.026 kW·h/g (HRT=4h),去除单位PO_4~(3-)-P电耗最低为0.112kW·h/g(HRT=2h); 16S rDNA结果表明,E-HFCWs基质表面生物膜的细菌主要属于β-proteobacteria,与对照组(Horizontal subsurface-flow constructed wetland system, HFCWs)相比,电解导致其门和属类数量相对减少,但是其中的Hydrogenophaga属的细菌和Xanthomonadaceae科的细菌含量有所增加,它们分别是以氢和亚铁离子作为电子供体的自养反硝化微生物,在电解-人工湿地脱氮过程中发挥作用。电解-生物质炭水平潜流人工湿地(Electrolysis-integrated biochar horizontal subsurface-flow constructed wetland system, E-B-HFCWs)以生物质炭作为湿地基质,同时添加铁电极构成电化学反应体系,不仅在较低的电耗条件下具有较高的脱氮除磷效果,而且实现了生物质炭的原位电化学改性,提高了生物质炭对NO_3~--N的吸附能力,而且出水中铁离子含量较低,出水色度大大降低。E-B-HFCWs对COD也具有一定的去除效果。对湿地植物生长和生理生化指标的结果分析表明电解对湿地植物生长影响较小。B-HFCWs基质生物膜主要以Proteobacteria、Actinobacteria、Acidobacteria门细菌为主。光伏电解人工湿地将电解引入人工湿地处理过程中,同时以光伏太阳能作为电解反应的能源,该湿地处理污水处理厂尾水的年运行结果表明,光伏电解人工湿地有利于降低电解反应所需电耗；以吸附材料生物质炭作为湿地基质有利于污染物的原位浓缩；湿地植物的根区微环境有利于牺牲阳极法对PO_4~(3-)-P的絮凝沉淀作用和湿地基质表面微生物的生长；光伏电解人工湿地较传统人工湿地强化了高浓度NO_3~--N和低浓度PO_4~(3-)-P的同步去除,有利于污水处理厂尾水的深度净化,具有良好的应用前景。
[Abstract]:Based on the characteristics of stable and efficient electrochemical reaction, the process and mechanism of combined electrochemical and constructed wetland nitrogen and phosphorus removal were studied in this paper. The effects of electrolysis equipment and process parameters such as RT on the removal efficiency of nitrate nitrogen (NO_3-N) and phosphate phosphorus (PO_4-3-P) were studied. The effects of electrolysis on the bacterial community structure of wetland plants and matrix biofilm were analyzed. A new photovoltaic electrolysis constructed wetland technology was developed and applied to the advanced purification of wastewater treatment plant tail water. The main conclusions are as follows: Electrolysis-integrated biofilter (E-BF) introduces electrolysis into the biofilter process, E-BF uses zeolite as the substrate, which is conducive to the removal of NH_ (3-) -N in simulated wastewater; iron electrode as the anode of electrolysis reaction, produces Fe ~ (2+), and Fe ~ (2+) is further oxidized to Fe ~ (3+). Fe~ (3+) and OH-formed Fe (OH) _3 flocculant in water, chemical reaction of Fe~ (3+) with phosphate and flocculation and precipitation of Fe (OH) _3 are beneficial to the removal of PO_4~ (3-) -P. The accumulation of N02-N and NO_3-N in matrix adsorbed ammonia nitrogen is less than that in control group (Biofilter, BF). Under different electrolysis conditions and influent concentration of PO_4~ (3-) -P, the lowest power consumption of removing PO_43-P was 1.1kW H / g.16S rDNA sequencing. The results showed that there was a certain amount of iron-sulfur bacteria in E-BF matrix, which played an important role in the biochemical transformation of iron. The results of simulation wastewater treatment by onstructed wetland system (E-HFCWs) show that the electrode arrangement will affect the removal efficiency of nitrogen and phosphorus, and the electrode arrangement with double cathodes is beneficial to the removal of NO_3-N and PO43-P; the most suitable current density, electrolysis time and HRT are 0.07 mA/cm2, 8 h and 8 h, respectively; and electrolysis will lead to the electrode removal. A relatively alkaline microenvironment with slightly higher temperature and lower oxidation-reduction potential (ORP) was formed around the wetland bed, which facilitated the simultaneous microbial transformation of NH_3-N and NO_3-N. The lowest power consumption per PO_4~ (3-) - P removal unit was 0.112 kW h/g (HRT = 2h) at 6 kW h/g (HRT = 4h), and 16S rDNA analysis showed that the bacteria on the surface of E-HFCWs substrate mainly belonged to beta-proteobacteria. Compared with the control group (Horizontal subsurface-flow constructed wetland system, HFCWs), electrolysis resulted in a relative decrease in the number of phyla and genera, but the number of bacteria on the surface of E-HFCWs decreased. Hydrogenophaga and Xanthomonadaceae, which are autotrophic denitrifying microorganisms with hydrogen and ferrous ions as electron donors, play an important role in the process of electrolytic-constructed wetland denitrification. The E-B-HFCWs (izontal subsurface-flow constructed wetland system) uses biomass charcoal as wetland substrate and adds iron electrode to form an electrochemical reaction system. It not only has a high effect of nitrogen and phosphorus removal under low power consumption, but also realizes in-situ electrochemical modification of biomass char and improves the NO_3~--N activity of biomass char. E-B-HFCWs also had a certain removal effect on COD. The results showed that electrolysis had little effect on wetland plant growth and physiological and biochemical indicators. B-HFCWs substrate biofilms were mainly composed of Proteobacteria, Actinobacteria and Acidobacteria. Photovoltaic electrolysis constructed wetland introduces electrolysis into the process of constructed wetland treatment, and uses photovoltaic solar energy as the energy source of electrolysis reaction. The annual operation results of the wetland treatment of wastewater treatment plant tail water show that photovoltaic electrolysis constructed wetland is conducive to reducing the electricity consumption needed for electrolysis reaction; biomass carbon as adsorbent material is used as wet. In situ concentration of pollutants was favored by the ground material; flocculation and sedimentation of PO_4~ (3-) - P by sacrificial anode method and growth of microorganisms on the surface of wetland substrate were favored by the root zone microenvironment of wetland plants; simultaneous removal of high concentration of NO_3~ - N and low concentration of PO_4~ (3-) - P was enhanced by the photovoltaic electrolysis constructed wetland compared with the traditional constructed wetland. The deep purification of tail water in water treatment plant has a good application prospect.
【学位授予单位】：南京大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X703
本文编号：2242280
[Abstract]:Based on the characteristics of stable and efficient electrochemical reaction, the process and mechanism of combined electrochemical and constructed wetland nitrogen and phosphorus removal were studied in this paper. The effects of electrolysis equipment and process parameters such as RT on the removal efficiency of nitrate nitrogen (NO_3-N) and phosphate phosphorus (PO_4-3-P) were studied. The effects of electrolysis on the bacterial community structure of wetland plants and matrix biofilm were analyzed. A new photovoltaic electrolysis constructed wetland technology was developed and applied to the advanced purification of wastewater treatment plant tail water. The main conclusions are as follows: Electrolysis-integrated biofilter (E-BF) introduces electrolysis into the biofilter process, E-BF uses zeolite as the substrate, which is conducive to the removal of NH_ (3-) -N in simulated wastewater; iron electrode as the anode of electrolysis reaction, produces Fe ~ (2+), and Fe ~ (2+) is further oxidized to Fe ~ (3+). Fe~ (3+) and OH-formed Fe (OH) _3 flocculant in water, chemical reaction of Fe~ (3+) with phosphate and flocculation and precipitation of Fe (OH) _3 are beneficial to the removal of PO_4~ (3-) -P. The accumulation of N02-N and NO_3-N in matrix adsorbed ammonia nitrogen is less than that in control group (Biofilter, BF). Under different electrolysis conditions and influent concentration of PO_4~ (3-) -P, the lowest power consumption of removing PO_43-P was 1.1kW H / g.16S rDNA sequencing. The results showed that there was a certain amount of iron-sulfur bacteria in E-BF matrix, which played an important role in the biochemical transformation of iron. The results of simulation wastewater treatment by onstructed wetland system (E-HFCWs) show that the electrode arrangement will affect the removal efficiency of nitrogen and phosphorus, and the electrode arrangement with double cathodes is beneficial to the removal of NO_3-N and PO43-P; the most suitable current density, electrolysis time and HRT are 0.07 mA/cm2, 8 h and 8 h, respectively; and electrolysis will lead to the electrode removal. A relatively alkaline microenvironment with slightly higher temperature and lower oxidation-reduction potential (ORP) was formed around the wetland bed, which facilitated the simultaneous microbial transformation of NH_3-N and NO_3-N. The lowest power consumption per PO_4~ (3-) - P removal unit was 0.112 kW h/g (HRT = 2h) at 6 kW h/g (HRT = 4h), and 16S rDNA analysis showed that the bacteria on the surface of E-HFCWs substrate mainly belonged to beta-proteobacteria. Compared with the control group (Horizontal subsurface-flow constructed wetland system, HFCWs), electrolysis resulted in a relative decrease in the number of phyla and genera, but the number of bacteria on the surface of E-HFCWs decreased. Hydrogenophaga and Xanthomonadaceae, which are autotrophic denitrifying microorganisms with hydrogen and ferrous ions as electron donors, play an important role in the process of electrolytic-constructed wetland denitrification. The E-B-HFCWs (izontal subsurface-flow constructed wetland system) uses biomass charcoal as wetland substrate and adds iron electrode to form an electrochemical reaction system. It not only has a high effect of nitrogen and phosphorus removal under low power consumption, but also realizes in-situ electrochemical modification of biomass char and improves the NO_3~--N activity of biomass char. E-B-HFCWs also had a certain removal effect on COD. The results showed that electrolysis had little effect on wetland plant growth and physiological and biochemical indicators. B-HFCWs substrate biofilms were mainly composed of Proteobacteria, Actinobacteria and Acidobacteria. Photovoltaic electrolysis constructed wetland introduces electrolysis into the process of constructed wetland treatment, and uses photovoltaic solar energy as the energy source of electrolysis reaction. The annual operation results of the wetland treatment of wastewater treatment plant tail water show that photovoltaic electrolysis constructed wetland is conducive to reducing the electricity consumption needed for electrolysis reaction; biomass carbon as adsorbent material is used as wet. In situ concentration of pollutants was favored by the ground material; flocculation and sedimentation of PO_4~ (3-) - P by sacrificial anode method and growth of microorganisms on the surface of wetland substrate were favored by the root zone microenvironment of wetland plants; simultaneous removal of high concentration of NO_3~ - N and low concentration of PO_4~ (3-) - P was enhanced by the photovoltaic electrolysis constructed wetland compared with the traditional constructed wetland. The deep purification of tail water in water treatment plant has a good application prospect.
【学位授予单位】：南京大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X703
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