Advances in the Study of Nitrogen and Phosphorus Removal Mechanisms in Constructed Wetlands

Constructed wetlands are wastewater treatment ecosystems composed of substrata, plants, microorganisms and water. We summarize herein recent research findings about nitrogen and phosphorus removal mechanisms in wastewater treated by constructed wetlands and the influencing factors, such as substrata, plants, microorganisms, hydraulic loads, temperature and dissolved oxygen. To increase the nitrogen and phosphorus removal efficiency and extend the fields of constructed wetland application, nitrogen and phosphorus removal mechanisms, influencing factors and techniques must be studied intensively in the future.     

人工湿地处理农业径流研究

为了处理农业径流的污染,本研究采用水平潜流人工湿地对农业径流进行处理试验,以减轻河流污染。结果表明,进水流量2.5m3/d运行条件下,水平潜流人工湿地有较好的处理效果。潜流人工湿地CODcr、TN、NH4+-N、TP的平均去除率均分别达到49.65%,51.37 %,56.24% 和59.12%;潜流人工湿地系统的出水CODcr、TN、NH4+-N、TP平均含量分别达到Ⅱ类水质的含量,Ⅴ类水质的含量, ,Ⅱ类水质的含和Ⅳ类水质的含量。通过对人工湿地处理系统影响因素分析表明：进水流量的控制非常关键,适宜的进水流量处理效果最佳。     

Reaction Kinetics of Three Types of Constructed Wetland for Advanced Domestic Wastewater Treatment

The removal efficiencies of different pollutants in subsurface flow constructed wetland (SSFW), surface flow constructed wetland (SFW) and combination flow constructed wetland(CFW) treating sewage plant effluent were comparatively analysed. The results were analyzed by using a reaction kinetics model. It is shown that COD, TN, TP are more effectively removed in SSFW than in other two types of wetland, and the kinetic constants are 0.29, 0.20, 0.28 m/d respectively. The SFW has higher removal rate on ammonia and the kinetic constant is 0.12 m/d. Temperature change greatly affects the kinetic constants of ammonia and total nitrogen removal reaction, whilst the influence on COD and TP are not significant. The pollutants removal efficiencies decrease greatly with the increase of hydraulic loading and areal loading. The increment of areal removal mass is reduced with the increase of areal loading in three types of wetland. It is strongly recommended that the constructed wetland be operated on low pollutants loading condition.     

北京翠湖人工湿地污水净化的效果分析

通过在北京翠湖构建人工湿地来处理污染水体,研究该人工湿地对pH、浊度、CODcr、TN、TP的去除作用。从人工湿地对污染物的去除效果来看,浊度、CODcr、TN和TP运行3月的平均去除率分别为42.659%、7.161%、25.583%和24.662%。结果表明,翠湖人工湿地处理的水体中pH随时间变化而有所降低,出水口pH值逐渐得到改善。翠湖人工湿地5个不同时间段（2009-6-3、2009-6-26、2009-7-9、2009-7-29、2009-8-17）浊度的平均去除率分别为66.459%、62.562%、33.343%、6.616%、44.314%。翠湖人工湿地对CODcr的去除率随时间变化有较小波动,5个时间段平均去除率分别为4.347%、4.716%、10.748%、9.370%、6.622%。TN平均去除率分别为15.465%、27.669%、30.507%、33.177%、21.098%,TP平均去除率分别2.688%、49.790%、21.538%、13.580%、35.714%。     

微污染水源人工湿地处理效果与植物作用分析

采用水平流人工湿地系统对沉砂后的微污染水源水进行了预处理试验,考察了处理效能与湿地植物作用。结果表明：水平流人工湿地系统对COD,TP,TN和NH4+-N平均去除率分别为49.89%,50.44%,53.41%和48.45%;湿地植物作用研究表明：一方面,植物通过吸收直接去除氮、磷,在生长季节作用更明显。而且在床体前部植物生长效果略好于后部,对氮、磷吸收也略高于后部。另一方面植物根系可以过滤、截留去除水中污染物,并为微生物提供附着表面,从而发挥了微生物的降解作用,这在人工湿地系统起重要的作用。     

人工湿地植物应用现状与问题分析

为了在人工湿地设计与施工时更好地确定植物类型,在分析中国目前人工湿地植物的主要应用类型的基础上,提出了水生类型、湿生类型、陆生类型的人工湿地植物分类新方法。同时,对人工湿地不同植物品种和不同季节的去污效果研究进行综述,最后分析出人工湿地植物研究存在着应用的植物种类少、景观价值低、受环境影响大、二次污染、植物净化机制有待进一步加强了解的5个主要问题,并提出研究发展的3个方向。     

Analysis of Phosphorus Removal in the Non-backflow Intermittent Aeration System

In this paper the phosphorus removal performance has been studied in Non-backflow Intermittent Aeration System (NBIAS), when the aeration duration and SRT were adjusted. At the same time, nitrogen removal was also studied. Test results show that when the cycle duration is 6 h., anaerobic duration 1.5h. sedimentation and displacement time 0.5 h. and SRT=20 d,aerobic ratio 0.42, the removal efficiency for CODcr, nitrogen and phosphorus will be 85%, 75% and 69%, respectively.     

扎龙湿地表层沉积物中磷形态的分布特征

表层沉积物中磷形态的浓度是衡量湿地富营养化程度的最基本指标,为了对研究区表层沉积物中总磷及磷形态的空间分布特征进行分析,通过SMT法对扎龙湿地表层沉积物中280个采样点的磷含量进行测量,在GIS的支持下,利用Kriging插值方法了解其空间差异并探究原因。结果表明,研究区表层沉积物中总磷（TP）含量在202~1014 mg/kg之间,主要以无机磷（IP）形态存在,平均占TP的56%。TP主要集中在研究区的中部地区,并呈现出由西南向东北递减的趋势,且南部和北部地区含量较低;各形态磷的分布特征均与TP相似;有机磷（OP）的分布特征主导了TP的分布;各形态磷之间均呈现显著相关,揭示出扎龙湿地表层沉积物中各形态磷间可能相互转化;研究区内源负荷严重,对扎龙湿地富营养化具有较大潜在威胁。     

Comparison of Dissolved Oxygen Distribution and Nitrogen Removal Effect in Wetlands with Different Structures

The dissolved oxygen distribution and nitrogen removal effect in different structures of wetlands were investigated by two groups of comparison experiments (vertical flow with horizontal flow; single stage with three stage horizontal flow). It was found that the different hydraulic flow patterns in different structures of wetlands would result in different oxygen distribution and nitrogen removal effect. The special structure design and hydraulic flow pattern of vertical flow wetland were favorable to its dissolved oxygen distribution, which could increase 0.17 mg/L in local area than that in horizontal flow wetland. The nitrogen removal effect of vertical flow wetland was better than that of horizontal flow wetland in the same operation conditions. The removal efficiency of NH+4-N and TN could increase 9% and 5% respectively in vertical flow wetland than that in horizontal flow wetland. Because of reaeration in contacting channels of three stage wetland, the removal efficiency of NH+4-N and TN reached 66% and 71% respectively, which improved 8% and 5% respectively than that of single stage wetland. In addition, three stage wetland could keep higher nitrogen removal effect even in low operation water level, and the range of its best hydraulic retention time(HRT) was extended.     

Orthogonal Experiments on Reclaimed Water Treatment by Coagulation Sedimentation and Constructed Wetland in Green Building

Orthogonal experiments were carried out for high grade gray water treated by combinational technique of coagulation sedimentation and constructed wetland. With the orthogonal experiment of coagulation sedimentation pre treatment, it is shown that the regression equations relating to effluent BOD5, cubage loads(Nv), temperature(T) and PAC addition dosage(ρ) is BOD5=2.05Nv-0.41T-0.82ρ+38.9. For the orthogonal experiment of constructed wetland post treatment, it is shown that the regression equations relating to effluent BOD5, cubage loads(NA), and temperature(T) is BOD5=1 190 NA-0.32T+12.2. Based on the two orthogonal regression equations, combined with reclaimed water quantity requirements in different seasons in buildings, an investment optimization model of combinational technique was established. According to the model, the reasonable scale of the reclaimed water treatment systems can be determined and treatment efficacy can be well predicted.     

污水化学沉淀法除磷研究进展

目前水体富营养化情况十分严重。随着社会对水体富营养化的关注不断提高和国家对水体富营养化的治理不断加强,污水排放中的磷含量控制越来越严格。化学沉淀法除磷在费用投入和除磷效果等方面都具有明显优势,应用前景十分广阔。为进一步促进化学沉淀法除磷研究的深入开展,综述了化学沉淀法除磷的原理、常用化学沉淀剂的种类及其研究现状、化学沉淀除磷的影响因素、化学/生物组合型除磷技术的发展现状,展望了化学沉淀法除磷的应用前景,并指出了化学沉淀法除磷的不足和今后的研究方向。     

坡度对云南红壤径流中磷素浓度的影响研究

水体富营养化的发生与农田土壤中磷的淋失有密切的关系。采用模拟降雨试验研究了土壤坡度对地表径流和亚地表径流中磷素浓度的影响。结果表明：在0°—10°范围内,地表径流中总磷、水溶性磷和颗粒态磷浓度和亚地表径流中水溶性磷浓度都随土壤坡度的增加而增加。亚地表径流中总磷和颗粒态磷在坡度为15°时均有一定程度的下降,其下降机理将做下一步分析研究。     

安徽省沿淮大豆种植区氮磷流失特征研究

为了探明沿淮地区大豆农民常规施肥种植过程中的氮磷流失情况,采用径流池法,通过2008—2012年野外径流小区试验,研究沿淮大豆种植区大豆生长季氮磷流失特征。5年监测结果表明:大豆种植季处于沿淮地区全年降雨旺盛时期,降雨量占全年降雨量的45.4%~73.27%;大豆生产季农田产流量表现为不施肥空白处理常规处理,不施肥空白处理大豆生长季径流量和产流系数分别为173.293~34.639 mm和8.27%~33.68%,常规施肥处理大豆生长季径流量和产流系数分别为175.366~30.347 mm和5.72%~34.08%;大豆种植生长季常规施肥处理总氮流失量为1.58~14.93 kg/hm2,总氮流失率为0.44%~5.66%,硝态氮流失比例为总氮的40.63%~64.59%,铵态氮流失比例为3.66%~18.16%;大豆种植生长季常规施肥处理总磷流失量为0.033~0.56 kg/hm2,常规施肥处理总磷流失率为0.17%~0.27%,可溶性磷流失比例为总磷的31.08%~53.31%。     

石灰性土植物磷胁迫的适应性调控机制研究

石灰性土因较高的Ca+浓度和较低的土壤含水量,导致土壤中有效态P含量较低,植物生长发育常受到P营养胁迫。笔者从元素营养角度综述了石灰性土中植物生长发育过程的控制因子及其适应性调控机制。重点对植物在P营养胁迫状态下的根系变异、根分泌物、菌根真菌侵染等方面进行了讨论。同时,对研究中存在的问题进行了简评,并对其研究前景作了展望。     

平和县琯溪蜜柚山地果园径流氮磷含量变化

为了解决平和县琯溪蜜柚过度种植,化肥、农药滥用导致环境污染的问题。通过实地调查与室内分析相结合的方法,调查了平和县琯溪蜜柚不同施肥状况山地果园径流氮磷含量情况。结果表明:(1)一年间果园径流磷含量(总磷和可溶磷含量)和氮含量(总氮、可溶性总氮、硝态氮、氨态氮含量)都有逐渐降低的态势,分别大于不同试验区汇水含量(山塘水、沟水、溪水和九龙江水);(2)径流N/P都大于6.5,果园径流磷含量为富营养化限制因素;果园径流硝态氮含量低于饮用水限制含量(10 mg/L);(3)试验区汇水全年总磷含量分别为0.403、0.280、0.503、0.417 mg/L,基本大于Ⅲ类水质要求(0.3 mg/L),全年氨氮含量分别为0.14、0.20、0.44、0.10 mg/L,达到Ⅱ类水质要求,总氮含量分别为3.77、3.49、3.89、3.38 mg/L,都大于Ⅴ类水质要求2.0 mg/L。果园径流总体上都达不到地表水环境质量标准要求,直接排放会产生水体富营养化。     

Approach to the Enhancement of Removal of Phosphorus and Nitrogen in Oxidation Ditch

In response to the characteristic of oxidation ditch and its limitation in removal of phosphorus and nitrogen,the research of the biological phosphorus and nitrogen removal in micro-environment and macroenvironment was reviewed.The process of enhancing phosphorus and nitrogen removal was discussed,the way to improve the phosphorus and nitrogen removal was presented:(1)the proper sequential arrangement of the locations of aerator,influent,effluent and return sludge to form the reversed A~2/O process;(2)forming more rigorously anaerobic zone by means of vertical flow circle;(3)the proper supply of oxygen,to avoid insufficiency of aerobic phosphorus uptake and nitrification with low oxygen supply;While to keep from overmuch waste of carbon source going against de-nitrification,and high oxygen concentration going against anaerobic phosphorus release due to high oxygen supply;(4)the proper hydraulic parameter and oxygen supply mode.