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| 海水养殖尾水人工湿地处理系统及其脱氮过程研究进展和展望 |
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李秋芬1, 田文杰1,2, 孙波1, 迟赛赛3, 罗梓峻4, 徐爱玲2, 宋志文5, 崔正国1
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1.中国水产科学研究院黄海水产研究所 农业农村部海洋渔业与可持续发展重点实验室 山东 青岛 266071;2.青岛理工大学环境与市政工程学院 山东 青岛 266520;3.中国水产科学研究院黄海水产研究所 农业农村部海洋渔业与可持续发展重点实验室 山东 青岛 266072;4.中国水产科学研究院黄海水产研究所 农业农村部海洋渔业与可持续发展重点实验室 山东 青岛 266073;5.青岛理工大学环境与市政工程学院 山东 青岛 266521
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| 摘要: |
| 利用人工湿地处理海水养殖尾水具有很大的应用前景，其中，脱氮是人工湿地的主要任务之一。基质上栽培的植物和附着的微生物参与的氮循环是人工湿地生物脱氮的主要路径，植物和多种氮代谢菌群在人工湿地内部相互协同与制约，构成了一个复杂的氮代谢网络。海水养殖尾水的高盐度和低碳氮比(C/N)又决定了此类人工湿地独特的处理环境和生物脱氮机制。同时，人工湿地的供氧模式、水力负荷(HRT)、水力停留时间(HLR)等水力条件参数对脱氮效能也有很大影响，对这些指标进行调控和优化，可以提高湿地的整体脱氮性能。本文从海水人工湿地的构建、基质的选取、耐盐植物的筛选、氮循环相关微生物以及运行参数调控四个方面，对近年来海水养殖尾水人工湿地生物脱氮方面的研究进展进行了综述和展望，以期为深入理解海水人工湿地脱氮机制和优化运行方式提供参考。 |
| 关键词: 海水养殖尾水 人工湿地 生物脱氮 耐盐植物 氮循环微生物 |
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| Research progress and perspect on constructed wetlands treatment system for maricultural wastewater and its nitrogen removal process |
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LI Qiufen1, TIAN Wenjie1,2, SUN Bo1, CHI Saisai3, LUO Zijun4, XU Ailing2, SONG Zhiwen5, CUI Zhengguo1
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1.Key Laboratory of Marine Fisheries and Sustainable Development, Yellow Sea Fisheries Research Institute,
Chinese Academy of Fishery Sciences, Ministry of Agriculture and Rural affairs, Qingdao 266071, China;2.School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266520, China;3.Key Laboratory of Marine Fisheries and Sustainable Development, Yellow Sea Fisheries Research Institute,
Chinese Academy of Fishery Sciences, Ministry of Agriculture and Rural affairs, Qingdao 266072, China;4.Key Laboratory of Marine Fisheries and Sustainable Development, Yellow Sea Fisheries Research Institute,
Chinese Academy of Fishery Sciences, Ministry of Agriculture and Rural affairs, Qingdao 266073, China;5.School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266521, China
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| Abstract: |
| In the process of mariculture, a large number of toxic and harmful substances such as organic matter, ammonia, and nitrite are produced during the metabolism of cultured organisms and the decomposition of feed residuals. If such maricultural wastewater is discharged without purification treatment, it will aggravate the occurrence of eutrophication in the receiving sea area. Constructed wetlands (CW) have received widespread attention due to their low operating costs, simple maintenance, and management advantages. Using CW to treat maricultural wastewater has great prospects. Nitrogen removal is one of the main tasks of constructed wetlands. The characteristics of high salinity and low C/N of maricultural wastewater result in the unique treatment environment and operating mechanism of CW. The substrate can adsorb nitrogen in the constructed wetlands, and nitrogen-cycling microorganisms such as nitrifying bacteria and denitrifying bacteria can attach to the surface to form biofilms. The selection of suitable substrate materials, in addition to zeolite, cinder, sand, and other commonly used water purification materials, can strengthen water purification. Given the low C/N characteristics of maricultural wastewater, materials with slow-release carbon sources can be selected as the filling substrate of constructed marine wetlands. For example, biological carbon sources such as corncob and wood chips, and polymer materials such as PCL and PLC, have recently been used as substrates to fill constructed wetlands and release carbon sources. Meanwhile, substrates that can drive the autotrophic denitrification process of microorganisms such as sulfur autotrophic, hydrogen autotrophic, and iron autotrophic have also been used as a solution. Plants are an important component of constructed marine wetlands, supporting nitrogen removal in four aspects: Nitrogen absorption, oxygen transport, carbon source secretion, and root enrichment of microorganisms. The high salinity environment determines that the wetland plants should be salt-tolerant, and the screening of salt-tolerant plants is a key step in constructed marine wetlands. Currently, Spartina alterniflora, Suaeda salsa, Salicornia bigelovii, Kandelia candel, and similar plants are chosen as candidate plants for constructed marine wetlands. The selection of plants should also consider local conditions, choosing salt-tolerant plants suitable for growing in the local environment. The nitrogen cycle of microorganisms is the main path of biological nitrogen removal in CWs. Various nitrogen-metabolizing bacteria cooperate and restrict each other in CWs, including autotrophic and heterotrophic bacteria, as well as aerobic and anaerobic bacteria. In the process of nitrogen removal in constructed wetlands, dissolved oxygen (DO) is an important environmental factor affecting the distribution and functioning of nitrogen-removing microorganisms. The relatively high DO in the upper layer of the constructed wetland favors the growth and reproduction of aerobic microorganisms, promoting the traditional nitrification process dominated by AOA, AOB, and NOB. The relatively low DO in the bottom layer is more conducive to the growth and colonization of anoxic and anaerobic microorganisms, favoring anaerobic denitrification, Anammox, and DNRA. The occurrence of Comammox can be driven under low nutrient and low oxygen conditions. These bacteria with nitrogen metabolism functions are distributed in different areas, cooperating and restricting each other, forming a complex nitrogen cycle network. Clarifying the basic path of the nitrogen cycle in seawater constructed wetlands is the fundamental basis for regulating the operating parameters of constructed wetlands. The low C/N of mariculture wastewater is not favorable for denitrification by microorganisms. Carbon sources can be supplemented with additional liquid carbon sources, solid carbon sources, and plant litter. DO is the key control index of constructed marine wetlands. The dissolved oxygen content in constructed wetlands is significantly correlated with the community composition of denitrification microorganisms. Therefore, oxygen supply regulation modes, such as continuous aeration, intermittent aeration, and tidal flow, may be effective measures for mariculture wastewater constructed wetlands to improve the overall nitrogen removal performance of wetlands. Accurate regulation of the oxygen supply mode and oxygen supply in constructed wetlands and optimization of dissolved oxygen distribution in different times and spaces within the system are the development trends of nitrogen removal technology in constructed wetlands in the future. The hydraulic operation conditions of CW play an important role in its nitrogen removal effect. Too high or too low indices will affect the efficiency of nitrogen removal in wetlands. Therefore, the optimal control values of hydraulic retention time (HRT), hydraulic loading rate (HLR), and other hydraulic parameters of constructed wetlands also need to be studied. The hydraulic conditions of constructed wetlands also have a significant impact on plant growth, affecting the purification efficiency of plants. In this paper, recent research progress and perspectives on constructed wetlands for the purification of maricultural wastewater and its biological nitrogen removal process were reviewed from four aspects: Selection of substrate, screening of salt-tolerant plants, nitrogen cycling microorganisms, and operation regulation. It is expected to provide a theoretical basis and support for regulating the actual operation of maricultural wastewater constructed wetlands and improving the technical level of maricultural wastewater treatment. |
| Key words: Maricultural wastewater Constructed wetlands Biological nitrogen removal Salt-tolerant plants Nitrogen cycling microorganism |
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