水平潜流人工湿地的脱氮机理及其影响因素研究

水平潜流人工湿地中氮的去除方式主要包括植物吸收、基质吸附和硝化-反硝化作用等,其中硝化-反硝化作用是其最主要的脱氮机理。水平潜流人工湿地的构造决定了其内部整体厌氧的环境,使其具有较好的反硝化脱氮效果。影响水平潜流人工湿地脱氮的主要因素包括溶解氧、基质、植物、碳源及运行条件等。探讨了影响湿地脱氮的主要因素,同时论述了提高湿地脱氮效果的措施,并对今后的相关研究方向进行了展望。     

人工湿地强化脱氮研究进展

脱氮效率不高一直是困扰人工湿地应用的问题之一,如何强化人工湿地脱氮已成为近年来的研究热点。人工湿地对于氮的去除作用主要有氮的挥发、水生植物的吸收、基质的吸附、沉淀以及微生物的硝化与反硝化作用,也发现了一些新的脱氮途径,如短程硝化反硝化、同步硝化反硝化等。从湿地结构改进、运行方式优化、建立湿地组合系统、基质优选、植物筛选、微生物调控等方面详细论述了人工湿地强化脱氮措施及净化效果,以期为人工湿地技术优化与工程应用提供参考。     

碳源补充促进人工湿地脱氮研究进展

介绍了人工湿地的脱氮机制和影响因素,以及常用的反硝化外加碳源。人工湿地的脱氮机制主要包括基质吸附、植物吸收和微生物硝化反硝化等。但进入人工湿地的污水往往碳氮比较低,限制了脱氮效率,往往需要添加外源碳来提高人工湿地的脱氮效果;结合微藻可同化吸收利用氮磷,并在死亡分解过程中会释放有机物的规律。认为可构建藻类-人工湿地耦合系统,利用藻类作为人工湿地反硝化过程的外加碳源,以提高人工湿地脱氮效率。     

溶解氧和碳源在人工湿地脱氮中的耦合关系分析

硝化-反硝化过程是人工湿地脱氮的主要途径。如何同时保障硝化-反硝化这一重要脱氮机制的畅通是提高湿地脱氮效率的关键。对溶解氧和碳源在人工湿地脱氮中的作用及其主要来源进行了描述,重点论述并分析了溶解氧和碳源在人工湿地脱氮中的耦合关系,合理调整进水中的碳氮比被认为是提高湿地脱氮效率的关键。     

人工湿地植物对氮素去除影响机制的研究进展

人工湿地植物通过直接作用与间接生态效应对系统脱氮过程发挥着至关重要的作用.其中,直接作用是湿地植物直接吸收利用无机氮;间接生态效应则是通过植物根系分泌氧和根系物质,以及影响氮素矿化作用,来改善脱氮微生物的生存环境,从而影响脱氮微生物的群落结构及硝化-反硝化过程,实现对湿地系统脱氮的影响.在此基础上,文章进一步阐述了植物对系统脱氮的影响机制,对人工湿地植物的选择、配置和高效脱氮人工湿地的设计进行了总结与展望.     

强化反硝化脱氮湿地外加碳源研究进展

人工湿地作为一种新型污水处理技术已被广泛应用,碳源是影响其反硝化脱氮的主要因素之一,针对污水中C/N比较低的问题,需向系统中额外投加碳源。在大量相关文献研究基础上,对强化反硝化脱氮人工湿地的外加碳源进行了总结,并比较了外加碳源的种类和及其优缺点。并对人工湿地外加碳源的研究进行了讨论和展望,为今后强化脱氮人工湿地外加碳源的深入研究提供了建议。     

潜流人工湿地对农村生活污水氮去除的研究

作者研究了潜流水平人工湿地处理农村生活污水中氮的去除效果，结果表明湿地进水TN负荷与出水TN负荷去除之间有较好的线性关系，随着水力停留时间的延长TN去除率也升高，停留时间为4d时，芦苇湿地和菖蒲湿地的脱氮效率可以达到60％以上。从脱氮效果看，芦苇湿地的略好于菖蒲湿地的，有植物系统明显好于无植物系统。在进水NO2^--N浓度小于0．062mg／L、NO3^--N浓度小于1．982mg／L的情况下，无论是连续运行还是间歇运行，大多数情况下，出水浓度都分别低于0．631mg／L和1．00mg／L，两者一般不会有较大的积累。试验分析了湿地脱氮的途径，微生物硝化／反硝化是人工湿地脱氮的主要途径，植物吸收、存储仅占湿地总氮去除量的10％左右，但是植物的存在间接地影响湿地脱氮的其它途径，对提高湿地氮去除率具有重要作用。     

人工湿地除氮影响因素的研究

介绍了生活污水人工湿地的生物脱氮技术及去除污水中氮污染物的机理。通过人工湿地脱氮技术,详细阐述了人工湿地氨氮的机理、影响因素,重点研究了氮素去除的关键过程即微生物的反硝化过程及其影响因素。为人工湿地污水处理工艺的推广应用提供科学依据。     

人工湿地增氧技术在污水脱氮中的应用

在人工湿地污水处理系统中,溶解氧对脱氮效果起着非常重要的作用。由于人工湿地自身构造的限制,湿地内溶解氧水平普遍较低,利用增氧技术可明显改善人工湿地内部的溶解氧水平,提高湿地硝化脱氮作用。对溶解氧在人工湿地脱氮中的作用及其主要来源进行了描述,探讨了影响人工湿地溶解氧水平的因素,重点论述了提高人工湿地溶解氧水平的途径,并对今后的相关研究方向进行了展望。     

内电解耦合人工湿地对某工业园区污水厂尾水的脱氮除磷效果

以工业园区污水处理厂尾水脱氮、同步除磷为目标,构建铁炭内电解人工湿地中试系统,通过内电解作用改善工业尾水可生化性,为反硝化脱氮提供更多可利用碳源,强化脱氮;同时,内电解产生的铁离子促进除磷。结果表明:铁炭内电解人工湿地对氮、磷及有机物有良好的同步去除能力,强化脱氮效果明显,冬季运行稳定;COD、氨氮、TN和TP全年平均去除率分别为55.6%、72.2%、54.6%和86.0%,其中出水COD、氨氮、TP浓度满足《地表水环境质量标准》(GB 3838—2002)Ⅳ类水质要求,TN出水浓度低于10 mg/L。高通量测序结果显示,铁炭内电解人工湿地内脱氮微生物数量明显高于普通人工湿地,在1号池及3号池两个处理单元检测到的与硝化有关的细菌丰度分别占到总生物量的6.66%和3.67%。     

人工湿地应用于小城镇污水处理的研究进展

小城镇污水处理是我国面临的急待解决的环境问题。分析人工湿地的分类与特点及去污机理,与其它污水处理技术比较,总结出人工湿地具有投资少、运行费用低、出水水质好、操作简单等优点。对人工湿地的应用前景进行了展望。     

人工湿地污染物去除动力学模型研究进展

人工湿地是处理污水的一种经济有效的方法。本文对其污染物去除动力学模型的研究现状及进展进行了概述,并对其今后发展的趋势作了展望。     

水力负荷对潜流湿地去除污水处理厂二级出水中氮磷的影响

采用水平-石灰石、水平-沸石、垂直-沸石、垂直-改性沸石等4种潜流湿地对污水处理厂二级出水进行深度处理研究,探讨各系统稳定运行条件下,不同水力负荷对4种潜流湿地脱氮除磷效果的影响,以及4种湿地的去除污染物效果的差异性。结果表明,当进水水质为污水处理厂二级排放标准时,在一定的运行条件下,与垂直潜流湿地相比,水平潜流湿地对氮素的去除效果受水力负荷影响更大。其中,水平-沸石潜流湿地对NH3-N的去除率最高达到(96.5±2.58)%,而水平-石灰石潜流湿地最低仅为(78.7±3.64)%;水平-沸石潜流湿地对TN的去除率最高达到(94.5±2.58)%,最低仅为(66.1±2.02)%。另外,与水平流湿地相比,垂直流湿地对污水中磷素的去除效果较好,同时,垂直-沸石湿地表现出了对磷素最佳的去除效果,其对PO43--P的去除率最高达到(72.1±2.29)%,而对TP的去除率最高最高达到(73.8±3.25)%。此外,当水力负荷为0.093 m3/(m2.d)时,上述4种湿地对磷素均表现出了最佳的去除效果。     

污水中抗生素的处理方法研究进展

因为抗生素对许多疾病的治愈有特效,人类和畜禽养殖业对其依赖性较强,所以抗生素的使用量与日俱增。但由于抗生素对环境的污染具有持久性,极大地威胁到生态环境和人类健康,而目前已有的污水处理工艺对此类物质的去除率较低,导致绝大多数抗生素直接进入到环境中,引起世界各国广泛关注。本文全面阐述了人工湿地法、土壤渗滤系统法、超声降解法、加强型活性污泥法和低温等离子技术这几种方法在处理抗生素污水的研究现状,指出目前常用的处理方法和新型处理方法对处理抗生素污水的不足之处,得出建立组合式人工湿地法、超声与其他方法联合使用等组合式工艺将成为以后的研究重点,同时还要进一步研究不同处理工艺的去除机理以及处理过程中所消耗的材料的再生和回收循环利用。     

Removal of nitrate from constructed wetland in winter in high-latitude areas with modified hydrophyte biochars

In high-latitude areas, nitrate treatment from constructed wetlands is often not so good in winter. The study aims to develop an efficient and economic technology to remove nitrate from constructed wetland under the conditions of winter temperature. We conducted laboratory experiments to investigate the removal of nitrate from aqueous solution and wastewater by modified hydrophyte biochars from constructed wetlands. The second-order model fit the nitrate desorption kinetics of modified hydrophyte biochars with a high coefficient of determination (R²>0.99). Freundlich isotherms performed well to fit the nitrate sorption data (R²>0.98) of modified hydrophyte biochars. Batch adsorption experiments also showed that both initial solution pH and coexisting anions could affect the adsorption of nitrate onto modified hydrophyte biochars. Our results suggested that modified hydrophyte biochars might be a promising alternative wastewater treatment technology for nitrate removal from constructed wetland in winter in high-latitude areas.     

人工湿地去污机理及其国内外应用现状

人工湿地中,不同污染物的去除机理不同,其去污影响因素也不同,有机污染物的去除影响因素主要是溶解氧水平,氮的去除影响因素主要包括植物,溶解氧水平,水力停留时间及污染负荷等,磷的去除影响因素主要是填料理化性质和植物．在应用方面,人工湿地在国内外一般用于处理生活污水,工业废水及农业点源污染等,但目前更趋向用于治理富营养化水体和水资源保护。本文在分析人工湿地影响因素和应用现状后,提出进一步提高污染物去除效果的设想。     

Treatment of domestic wastewater by subsurface flow constructed wetlands in Jordan

The use of subsurface flow constructed wetlands for treating domestic wastewater in Jordan is described. The objective was to study the performance of subsurface flow constructed wetlands as a low-cost technology for treating domestic wastewater. Results show that subsurface flow constructed wetlands are capable of reducing biochemical oxygen demand (BOD), different forms of nitrogen, total suspended solids (TSS), fecal coliform count (FCC), and total coliform count (TCC). However, removal efficiencies differ from bed to bed and from month to month. Results show that there is strong correlation between BOD₅ removal efficiency and BOD₅ loading in kg/ha, which is defined as BOD₅ loading rate in kg/ha.d multiplied by residence time. The coefficient of determination (R²) for the six beds varied from 0.827 for bed number one to 0.608 for bed number four. Total nitrogen, ammonia nitrogen, and nitrate nitrogen reductions were observed, which suggestthat, nitrification as well as denitrificationtookplace in the beds. TSS reduction was observed in all beds. However, removal efficiency differed from bed to bed and for the same bed from month to month. Total and fecal coliform counts were reduced by one to three logs, because influent was high in total and fecal coliform counts were still high.     

Performance evaluation of hybrid constructed wetlands for the treatment of municipal wastewater in developing countries

In developing countries, high cost of conventional wastewater treatment is a major hindrance in its application. Constructed wetlands (CWs) offer low-cost and effective solution to this issue. The current study aimed to evaluate an innovative maneuver of CWs i.e. hybrid flow constructed wetlands (HCWs) for municipal wastewater (MWW). The HCWs included two lab scale CWs; one horizontal and one vertical, in series. Local plant species were used. HCWs were operated in both, batch and continuous mode. Batch mode was used to (1) optimize detention time and (2) find pollutants removal efficiency. Continuous operation (at batch optimized retention time) was carried out for the evaluation of mass removal rate, r (g·m^-2·d^-1), volumetric rate constant, K_v (per day) and areal rate constant, K_a (m·d^-1). Among two local plants tested, Pistia stratiotes gave better removal efficiency than Typha. Optimum detention time in HCWs was found to be 8 days (4 + 4 each). The optimum COD, BOD, TSS, TKN and P removal observed for Pistia stratiotes planted HCWs was 80%, 84%, 82%, 71% and 88% respectively. Effluent standards for COD, BOD and TSS were met at optimum conditions. The values of K_a and K_v demonstrated that more removal occurred in vertical flow as compared to horizontal flow CW.     

Investigation of protozoa as indicators of wastewater treatment efficiency in constructed wetlands

Wetlands represent an efficient wastewater treatment technique, with several benefits over the conventional activated sludge system. Microfaunal community is of outmost importance in treatment processes as the microorganisms are able to achieve substantial decontamination through biodegradation. The objectives of this work were the monitoring of protozoan's abundance and diversity in the matrix of six bench scale Free Water Surface constructed wetlands and the investigation of their applicability as indicator organisms for treatment efficiency in these systems. A correlation between the phosphorous and Total Coliforms removal rates was observed in the presence of increased protozoan taxa, while removal of organic loading and inorganic nitrogen was increased in the case of increased protozoan diversity in the soil/water interface. Results revealed that protozoa may be used as bioindicators of treatment efficiency in constructed wetlands; in addition their presence was related to the effluent quality.     

A case study of the performance of pilot scale light weight aggregates (LWA) based hybrid soil filters in Estonia

Two pilot scale experimental hybrid soil filters (SF) filled with light weight aggregates were established during the summer of 2005 for the treatment of different types of wastewater, with the aim of developing compact hybrid constructed wetlands (CW) for use in cold climates. Both SFs are designed on the same principle: a vertical subsurface flow filter followed by a horizontal subsurface flow filter. Six different operational regimes were tested during the experiments. With a decrease in wastewater and pollutant load and the larger re-circulation of wastewater, purification efficiency increased in terms of most water quality indicators. The highest purification efficiencies in the Nõo SF, 99% and 82% for BOD₇ and N_tot removal respectively, were achieved when the re-circulation rate of 300% was applied and in the Rämsi SF, 99% and 87% for BOD₇ and N_tot removal respectively, were achieved, when the re-circulation rate of 300 to 600% was applied. In order to achieve effective organic matter removal, nitrification/denitrification and TSS removal, the re-circulation rate must be from 100 to 300% of the inflowing wastewater. The re-circulation of wastewater in overloaded systems is a good solution for the improvement of the aeration and overall purification efficiency of CWs.