水平潜流人工湿地在不同水力负荷下的水力效率及可视化分析

构建水平潜流人工湿地装置,通过NaCl示踪脉冲实验,得到不同水力负荷条件下的水力停留时间分布密度曲线,根据不同停留时间的关系计算相对水力效率,并利用染料,进行不同水力负荷下的可视化示踪实验,通过MATLAB处理得到高对比度的流态图像。观察“死区”分布,计算“死区”相对面积用以表征其水力效率。结果表明,湿地装置进水水力负荷较高或较低时,水力效率均较低,且水力负荷较大时更明显;水力分布散度（σ2θ）的大小会对水平潜流人工湿地水力效率造成较大影响;在不同水力负荷下,采用水力学效能（λ）所得到的排序结果相比短路值（s）和有效体积比（e）更能代表实际水平潜流人工湿地的水力效率。     

曝气对水平潜流人工湿地水力特性的影响

通过构建曝气及未曝气潜流人工湿地小试实验系统,以NaCl为示踪剂开展示踪实验,研究曝气对人工湿地水力特性的影响。实验结果表明,两对比系统均存在不同程度的短流及死区现象,短流主要发生在床体表层,而死区则存在于床体底层。其中未曝气人工湿地系统的流场分布不均匀现象较为严重,示踪剂滞留在床体底层难以回收,系统水力效率较低(0.56)。比较而言,由于气流对水体的扰动作用,曝气对人工湿地系统水力效率有明显改善作用,减缓了床体表层水流速度,提高了示踪剂回收率,缩小了死区的范围,曝气人工湿地系统的水力效率为0.75。     

水平潜流人工湿地处理太原市城市再生水的运行效能

以山西省太原市某污水厂的高氮低碳尾水为研究对象,开展基于3床并联的水平潜流人工湿地处理尾水的中试研究。研究结果表明,该人工湿地系统启动2个月进入稳定运行期;稳定运行期3个床体的出水水质除TN外其余指标均满足《地表水环境质量标准》（GB3838—2002）中Ⅳ类水体标准,TN指标满足《城镇污水处理厂污染物排放标准》（GB18918．2002）中一级A标准,该湿地系统出水可直接用于补充景观用水;稳定运行期3床的植物与基质的配置更适合处理同类尾水,3个床体对各污染物的去除效果均为3床〉2床〉1床;本系统中填料对污染物处理效果的影响大于植物对污染物处理效果的影响,最优填料顺序依次为沸石、砾石和钢渣,最适植物栽种顺序为芦苇、香蒲、美人蕉、黄菖蒲和芦苇。     

水力负荷与有机负荷协同作用对人工湿地微生物群落结构的影响

以单层基质结构(CW1)、3层基质结构(CW3)、6层基质结构(CW6)的水平潜流人工湿地系统为对象,考察水力负荷及有机负荷对不同人工湿地系统去除COD、总悬浮固体(TSS)效果的影响,同时利用高通量测序技术,分析高负荷条件下系统微生物群落结构。结果表明,不同水力负荷运行条件下,随着有机负荷的提高,CW1、CW3、CW6湿地系统对COD、TSS的去除率均表现出先升高后下降的趋势,总体看来,在相同运行条件下CW6湿地系统COD、TSS的去除率最高。群落结构分析表明,不同人工湿地系统微生物结构存在相似性,但湿地床体的基质结构会对微生物群落结构产生一定影响,总的来说分层填充的人工湿地系统微生物群落结构更为稳定,对污染物的去除效果更好。     

水平潜流人工湿地脱氮功效中植物的作用

为了研究芦苇(Phragmites australis)在收割期前/后、湿地床体内部各个区域内、一年四季中在水平潜流人工湿地脱氮效用所起的作用,实验设置了有/无植物2组平行反应器。结果表明,芦苇在收割前/后对于水平潜流人工湿地脱氮效果均有促进作用,植物地上部分氮吸收量占湿地脱氮量的10.2%。在芦苇收割前/后(5月~9月、10月~次年5月),芦苇湿地日均脱氮量分别是无植物湿地的1.55倍与1.11倍。高、矮芦苇不同组织中总氮浓度分布趋势一致,2种芦苇各组织含量分别为:穗(28.69 g/kg)>叶(13.69 g/kg)>茎(5.31 g/kg)、穗(28.06 g/kg)>叶(14.61 g/kg)>茎(8.46 g/kg)。在湿地的各个沿程区域,总氮、氨氮累加去除率变化趋势一致,并且从反应器前部到尾部呈上升趋势,从上部到下部呈下降趋势。有芦苇湿地的脱氮效用优于无植物湿地,且底部氮积累含量也较少。一年四季中有芦苇湿地在各个季节脱氮量是无植物湿地的1.06~1.47倍。     

水平潜流人工湿地流场数值模拟与结构优化分析

为了解决传统水平潜流人工湿地在床体结构设计方面的随意性与经验化问题,以流场均匀分布为目标,利用数值模拟方法对人工湿地床体结构参数进行优化,包括人工湿地基质填充厚度、床体长宽比例、构建尺度、主体填料区的分层填充方式,解析基质结构的配置规律,实现各参数的定量化。模拟结果表明,填料的分层配置对流场分布的影响很大。在基质厚度为0.6 m,长宽比为5∶3,且填料按照渗透系数指数规律分层填充的情况下,流场分布较均匀。在此基础上,根据模拟结果所确定的结构参数构建潜流人工湿地小试装置,并与传统结构人工湿地进行对照,对模拟结果进行验证。实验结果表明,当水力停留时间(HRT)为36 h时,分层填充与单层填充方式的人工湿地对COD、TP和TN的平均去除率分别为64.89%、82.72%、69.69%和29.84%、39.15%、31.83%,结构优化后的人工湿地净化效果得以显著提升。     

Optimal conditions for chlorothalonil and dissolved organic carbon in horizontal subsurface flow constructed wetlands

The most efficient system of horizontal subsurface flow constructed wetlands (HSSFCW) for removing dissolved organic carbon (DOC) in the presence of chlorothalonil pesticide (CLT) present in synthetic domestic wastewater was determined using the macrophyte Phragmites australis. Two concentrations of CLT (85 and 385 μg L^?1) and one concentration of glucose (20 mg L^?1) were evaluated in four pilot scale horizontal surface flow constructed wetlands coupled with two sizes of silica gravel, igneous gravel, fine chalky gravel (3.18–6.35 mm), coarse gravel (12.70–25.40 mm) and two water surface heights (20 and 40 cm). For a month, wetlands were acclimated with domestic wastewater. Some groups of bacteria were also identified in the biofilm attached to the gravel. In each treatment periodic samplings were conducted in the influent and effluent. Chlorothalonil was quantified by gas chromatography (GC-ECD m), DOC by an organic carbon analyzer and bacterial groups using conventional microbiology in accordance with Standard Methods. The largest removals of DOC (85.82%–85.31%) were found when using fine gravel (3.18–6.35 mm) and the lower layer of water (20 cm). The bacterial groups quantified in the biofilm were total heterotrophic, revivable heterotrophic, Pseudomonas and total coliforms. The results of this study indicate that fine grain gravel (3.18–6.35 mm) and both water levels (20 to 40 cm) can be used in the removal of organic matter and for the treatment of agricultural effluents contaminated with organo-chloride pesticides like CLT in HSSFCW.     

不同水生植物类型表面流人工湿地系统对污水厂尾水深度处理效果

为了减少污水厂尾水直接排放后对地表自然水体造成一定的污染负荷和生态毒害,选择了5种南方常见的水生植物构建不同的表面流人工湿地处理模拟污水厂尾水,研究在室外动态条件下其对污水厂尾水中污染物的去除效果,并探讨季节变化对人工湿地运行效果的影响。结果表明:5种水生植物类型的表面流人工湿地系统对模拟污水厂尾水具有较好的处理效果,并且表现出随运行时间的延长而呈上升的趋势;各组系统之间对COD的去除不存在明显的统计学差异(p>0.05);风车草+再力花组合挺水植物湿地对TN和TP的去除率最高,其次是苦草和黑藻沉水植物湿地系统,紫叶美人蕉+粉花美人蕉组合生态浮岛和风车草+再力花组合生态浮岛效果较差;在不同季节条件下的污染物去除率由高到低的顺序为:夏季>春季>冬季;温度与COD的去除率无显著相关性,但与TN和TP的去除率呈显著的相关性。     

Composting plant leachate treatment by a pilot-scale,three-stage,horizontal flow constructed wetland in central Iran

Environmental Science and Pollution Research - Handling and treatment of composting leachate is difficult and poses major burdens on composting facilities. The main goal of this study was to...     

Purification of leachate from sludge treatment beds by subsurface flow constructed wetlands: effects of plants and hydraulic retention time

Environmental Science and Pollution Research - Sludge treatment beds (STBs) have been used widely in many countries due to low energy consumption, low operating and maintenance costs, and better...     

植物种类与水力负荷对人工湿地去除污染物的交互作用

人工湿地去污效能不仅受水力负荷(HL)影响,还与植物种类有关。为研究这2种因素对污染物去除的交互作用,根据植物根系长度,分别构建短根型、中根型及长根型植物潜流人工湿地中试系统,在运行稳定后,考察不同植物种类在不同水力负荷(152、230、305和460 mm/d)下的去污效果。结果表明:植物种类对COD去除率的影响差别不显著,对氮磷去除率有显著影响,且去除率符合长根型 > 中根型 > 短根型;水力负荷对COD、TN、NH4+-N和TP的去除均有显著影响,随着水力负荷减小去除率均逐渐升高;植物种类与水力负荷的交互作用对各污染物去除率均有显著影响,且受水力负荷影响较大,TN、NH4+-N的去除在水力负荷较小时交互作用较明显,COD去除的最优HL为230 mm/d。因此,在人工湿地设计时应考虑植物种类与水力负荷的交互作用。     

Effect of the inlet-outlet positions on the hydraulic performance of horizontal subsurface-flow wetlands constructed with heterogeneous porous media

Effects of the inlet and outlet position on flow patterns of saturated fluids in a horizontal subsurface-flow constructed wetland were investigated experimentally using a quasi two-dimensional flow cell representing a vertical cross-section in the longitudinal direction of the wetland. The filter medium consisted of glass beads that were either uniformly sized or a mixture of sizes with a distribution corresponding to wetland filter media. Flow through the filter bed was visualized by injecting dyed fluid into the water-saturated model. Next, breakthrough curves were obtained using chloride tracer. Flow through the homogeneous filter formed by uniformly sized beads displayed a clear density-driven component. Using mixed sizes, finer and coarser beads tended to separate into alternating and incomplete layers. Flow occurred preferentially along roughly horizontal high-conductivity paths of coarser filter material. Density-driven vertical flow was much slower than the horizontal flow. Nevertheless, appropriate positioning of the inlet and less importantly the outlet could to some extent mitigate the dominant effect of the medium stratification on the flow patterns. Using inlet-outlet configurations that forced the flow through larger portions of the filter bed by injecting into low-conductivity layers and opposing the gravity-driven flow increased the treatment efficiency.     

水力负荷对改良型垂直流人工湿地降解模拟污水厂尾水效果的影响

为确定改良型垂直流人工湿地降解模拟污水厂尾水的最佳水力负荷,采用生物炭和活性炭改良、微生物强化以及同时添加生物炭、活性炭和微生物改良强化的3套垂直流人工湿地系统,研究了其在3种水力负荷条件下(0.25、0.5和1 m3·(m2·d)−1),对模拟污水厂尾水中污染物的去除效果。结果表明,3套垂直流人工湿地系统均在低水力负荷(0.25 m3·(m2·d)−1)时对模拟污水厂尾水中$ {{\rm{NH}}_4^ + }$-N、TN、TP和COD的去除率较高,但随着水力负荷的增大其去除率逐渐降低。3套垂直流人工湿地系统对$ {{\rm{NO}}_3^{\rm{ - }}}$-N的去除率均在高水力负荷(1 m3·(m2·d)−1)时较高,且随着水力负荷的变大,其去除率逐渐升高,但去除率的增长幅度变缓;实验证明,生物炭和活性炭改良基质能够提高湿地系统对$ { {\rm{NH}}_4^ + }$-N、TN、TP和COD的去除效果,并且在低水力负荷时对$ {{\rm{NH}}_4^ +} $-N、TN和COD的去除拥有更好的改良效果,而对TP去除的改良则在高水力负荷时优于在低水力负荷时。厌氧-异养反硝化菌能够提高湿地系统对$ {{\rm{NH}}_4^ + }$-N、$ {{\rm{NO}}_3^{\rm{ - }}}$-N和TN的去除效果,并且在高水力负荷时对$ { {\rm{NO}}_3^{\rm{ - }}}$-N的改良效果优于低水力负荷,而在低水力负荷时对$ { {\rm{NH}}_4^ +} $-N和TN具有更好的改良效果。综合考虑多种污染物的去除效果,确定3套改良型垂直流人工湿地系统的最佳水力负荷为0.5 m3·(m2·d)−1。     

Behavior of selected priority organic pollutants in horizontal subsurface flow constructed wetlands: a preliminary screening

A discrete injection experiment was carried out in a constructed wetland to evaluate the behavior of selected priority pollutants. A horizontal subsurface flow pilot plant located in the NE of Spain was selected for this study. A total of eight European Priority Pollutants listed in the Water Framework Directive were considered, including a commonly used herbicide (mecoprop). The pollutants encompassed a variety of chemical classes and physicochemical properties. They included organochlorine, organophosphorus, phenols, chloroacetanilides, triazine, phenoxycarboxylic acid and phenylurea pesticides. A time series of composite effluent samples and discrete gravel bed samples from the wetland were analyzed. Response curves for all the pollutants injected from effluent concentrations were obtained and compared with the tracer (clofibric acid). On the basis of an analysis of the samples taken 21 days after the injection, priority pollutants were classified into four groups according to their removal efficiency. These groups were (i) the highly efficiently removed (>90%), namely lindane, pentachlorophenol, endosulfan and pentachlorobenzene; (ii) the efficiently removed (80-90%), namely alachlor and chlorpyriphos; (iii) poorly removed (20%), namely mecoprop and simazine; and (iv) recalcitrant to elimination, namely clofibric acid and diuron. Taking into account the poor accumulation of the injected contaminants in the gravel bed (0-20%), biodegradation and plant uptake are postulated as the most likely elimination pathways for the pollutants.     

Microbial abundance and community in subsurface flow constructed wetland microcosms: role of plant presence

In this research, the role of plants in improving microorganism growth conditions in subsurface flow constructed wetland (CW) microcosms was determined. In particular, microbial abundance and community were investigated during summer and winter in Phragmites australis-planted CW microcosms (PA) and unplanted CW microcosms (control, CT). Results revealed that the removal efficiencies of pollutants and microbial community structure varied in winter with variable microbial abundance. During summer, PA comprised more dominant phyla (e.g., Proteobacteria, Actinobacteria, and Bacteroidetes), whereas CT contained more Cyanobacteria and photosynthetic bacteria. During winter, the abundance of Proteobacteria was >40 % in PA but dramatically decreased in CT. Moreover, Cyanobacteria and photosynthetic bacterial dominance in CT decreased. In both seasons, bacteria were more abundant in root surfaces than in sand. Plant presence positively affected microbial abundance and community. The potential removal ability of CT, in which Cyanobacteria and photosynthetic bacteria were abundant during summer, was more significantly affected by temperature reduction than that of PA with plant presence.     

不同填料潮汐流人工湿地处理SBR尾水的对比

通过构建室内潮汐流沸石-石灰石混合填料和沸石填料人工湿地装置,探讨了不同基质人工湿地对SBR尾水中污染物的去除效果。结果表明,沸石对NH4+-N的吸附能力强,且潮汐间歇运行方式使系统一直保持高效的去除NH4+-N的能力,石灰石中Ca、Mg含量高,对P有较好的吸附。潮汐流沸石-石灰石混合填料、沸石填料人工湿地对NH4+-N的去除率分别为99.8%、96.7%,对TP的去除率分别为59.6%、24.9%。石灰石呈中性偏碱性,有利于水中硝化菌、反硝化菌和某些异养菌群的生长。潮汐流沸石-石灰石混合填料、沸石填料人工湿地对TN的去除率分别为43.0%、28.0%,对COD的去除率分别为43.4%、36.7%。沸石-石灰石混合填料人工湿地上层基质中微生物量最高,达到20.45 nmol·g-1填料（相当于E.coli大小的细胞2.0×109个）。2组系统中微生物量具有较明显的分层现象,且上层高于下层,这与污染物随水流推流方向的浓度变化一致。     

Performance of an integrated system combining microalgae and vertical flow constructed wetlands for urban wastewater treatment

Environmental Science and Pollution Research - The present study investigated the performance of an integrated system, combining the sequential use of microalgae (MA) and vertical flow constructed...     

人工湿地植物无损监测方法的建立与应用

人工湿地植物生物量的测定是研究人工湿地植物生长特性和去污性能的重要基础。目前常用的人工湿地植物生物量的测定方法繁琐,难以实现无损检测。以湿地植物梭鱼草和香蒲为例,结合自主设计的人工湿地植物生长信息提取软件,快捷、无损地测定湿地植物投影面积和质量,提出人工湿地植物无损监测方法。结果表明:湿地植物梭鱼草、香蒲的植株投影面积与植株株高呈极显著的线性相关关系,相关系数R分别为0.834~0.940 和0.707~0.904(P<0.01);梭鱼草的平均植株投影面积与其所在人工湿地池的TN、TP累积量具有显著相关性(P<0.05),香蒲的平均植株投影面积与其所在人工湿地池的TN、TP累积量相关性显著性系数分别为P=0.002和P=0.056。     

Heterotrophic bacterial activities and treatment performance of surface flow constructed wetlands receiving woodwaste leachate.

Heterotrophic activities were investigated by measuring 3H-leucine incorporation to bacterial protein and 14C-glucose turnover in surface flow constructed wetlands receiving woodwaste leachate. No significant longitudinal variation was found in heterotrophic activities of bacterioplankton. An open wetland, a vegetated wetland, and a fertilized vegetated wetland were used to examine the effects of vegetation and ammonium nitrate amendment. There was not a significant difference in treatment performance among the three wetlands, except for a significant pH increase and more efficient volatile fatty acids removal in the fertilized wetland. The fertilized wetland had the highest leucine incorporation rate and shortest glucose turnover time accompanied by the lowest glucose mineralization percentage, followed by the open wetland, then the vegetated wetland. Planktonic and sedimentary bacteria contributed to the majority of the total heterotrophic activities; epiphytic bacteria played a minor role. Heterotrophic activities were influenced by the availability of nutrient, electron acceptor, and organic substrate.     

Effect of vegetation in pilot-scale horizontal subsurface flow constructed wetlands treating sulphate rich groundwater contaminated with a low and high chlorinated hydrocarbon

In order to characterize the effect of vegetation on performance of constructed wetlands (CWs) treating low and high chlorinated hydrocarbon, two pilot-scale horizontal subsurface flow (HSSF) CWs (planted with Phragmites australis and unplanted) treating sulphate rich groundwater contaminated with MCB (monochlorobenzene, as a low chlorinated hydrocarbon), (about 10 mg L⁻¹), and PCE (perchloroethylene, as a high chlorinated hydrocarbon), (about 2 mg L⁻¹), were examined. With mean MCB inflow load of 299 mg m⁻² d⁻¹, the removal rate was 58 and 208 mg m⁻² d⁻¹ in the unplanted and planted wetland, respectively, after 4 m from the inlet. PCE was almost completely removed in both wetlands with mean inflow load of 49 mg m⁻² d⁻¹. However, toxic metabolites cis-1,2-DCE (dichloroethene) and VC (vinyl chloride) accumulated in the unplanted wetland; up to 70% and 25% of PCE was dechlorinated to cis-1,2-DCE and VC after 4 m from the inlet, respectively. Because of high sulphate concentration (around 850 mg L⁻¹) in the groundwater, the plant derived organic carbon caused sulphide formation (up to 15 mg L⁻¹) in the planted wetland, which impaired the MCB removal but not statistically significant. The results showed significant enhancement of vegetation on the removal of the low chlorinated hydrocarbon MCB, which is probably due to the fact that aerobic MCB degraders are benefited from the oxygen released by plant roots. Vegetation also stimulated completely dechlorination of PCE due to plant derived organic carbon, which is potentially to provide electron donor for dechlorination process. The plant derived organic carbon also stimulated dissimilatory sulphate reduction, which subsequently have negative effect on MCB removal.