Effects of Cd^(2+) and Pb^(2+) on the substrate biofilms in the integrated vertical-flow constructed wetland

The effects of single Cd^(2+)and Pb^(2+),and combined Cd^(2+)and Pb^(2+)on dehydrogenase activity and polysaccharide content of the substrate biofilms in the integrated vertical-flow constructed wetland(IVCW)were studied.Dehydrogenase activities decreased linearly with the increasing concentrations of Cd^(2+)and Pb^(2+)at different times(6,24,72,and 120 h).The activities at both 6 and 24 h were significantly higher than that at 72 and 120 h in the case of single and combined treatments.The single Cd^(2+)and...

Spacial Distribution Characteristics, Activity and Degradation Capability of the Biofilm in Integrated Vertical-flow Constructed Wetland

The spacial distribution characteristics, activity and degradation capability of the biofilm in integrated vertical-flow constructed wetland were investigated. Results showed that the biofilm widely distributed in the substrate of integrated vertical-flow constructed wetland and mainly in the 0-10 cm top layer where the activity ofdehydrogenase of the biofilm was also higher than that of other layers. The water quality could also affect the activity of the biofilm, for the TF（1,3,5-Triphenylformazan） amount reduced by the biofim incubated in water of the higher eutrophication was larger, too. The PCP （pentachlorophenol） removal rate by the substrate with biofilm was 1.5 times that without biofilm. In total, the biofilm of the down-flow chamber appeared larger biomass, higher dehydrogenase activity and stronger degradation capability of organic contamination than that in up-flow chamber and it was the major place for removal of the organic matters in waste water.

Treatment Efficiency of Integrated Vertical-Flow Constructed Wetland for Saline Wastewater

The integrated vertical-flow constructed wetland（IVCW） was simulated with three suits of designed experiment columns planted with Kandelia candel.Units A,B and C were irrigated with sewage of different salinity（A：10‰ B：20‰,C：30‰）,respectively.The removal rates of dissolved organic carbon（DOC）,NH3-N and NO3--N dropped 90.4%-48.6%,80.2%-40.3% and 84.8%-60.9%,respectively,when salinity increases from 10‰ to 30‰.The removal rate of TP increased 14%-31.2%,oppositely.A 20-day inflow salinity drastic change shock affective trial was done on units D and E.Unit D was used as a control and irrigated with saline sewage（20‰）.Unit E was irrigated with sewage with low salinity（5‰） as a salinity drastic change shock on the third and fourth days.DOC,NH3-N and NO3--N removal efficiency of unit E showed a three-stage process of change,＂rapidly decrease,increase beyond the normal standard,and then back to the normal standard＂.TP removal value was negative during the 2-day shock period.

Activities of Urease and Phosphatase in Integrated Vertical Flow Constructed Wetland and Purification Effect of Black and Malodorous River

[Objective]The activities of urease and phosphatase in integrated vertical flow constructed wetland and purification effect of black and malodorous river were studied.[Method]Honeycomb stone and soft filler were used as matrix,the biological grid integrated vertical flow constructed wetland system was built to strengthen treatment for black and malodorous river,and the activities of urease and phosphatase of two fillers in different functional areas of constructed wetland were tested to study the film formation property of two fillers in different functional areas.[Result]Both urease and phosphatase activities on biofilm of soft filler were significantly higher than on biofilm of honeycomb stone filler;indicating that choosing soft filler was more advantageous to the growth of biofilm;and urease activity had significant correlation with total nitrogen removal rate,while phosphatase activity had no significant correlation with total phosphorus removal rate.[Conclusion]This study provided evidences for utilizing the activities of urease and phosphatase to evaluate the purification effect of black and malodorous river and choose appropriate filler.

Enhancing treatment efficiency of swine wastewater by effluent recirculation in vertical-flow constructed wetland

Livestock wastewater has been a major contributor to Chinese cultural eutrophication of surface waters. Constructed wetlands are under study as a best management practice to treat wastewater from dairy and swine operations, but the removal efficiency of pollutants is relatively low. Enhancing the treatment efficiency of livestock wastewater by effluent recirculation was investigated in a pilot-scale vertical-flow constructed wetland. The wetland system was composed of downflow and upflow stages, on which narrow-leaf Phragmites communis and common reed Phragraites Typhia are planted, respectively; each stage has a dimension of 4 m^2 （2 m × 2 m）. Wastewater from facultative pond was fed into the system intermittently at a flow rate of 0.4 m^3/d. Recirculation rates of 0, 25%, 50%, 100% and 150% were adopted to evaluate the effect of the recirculation rate on pollutants removal. It shows that with effluent recirculation the average removal efficiencies of NH4-N, biological oxygen demand （BOD5） and suspended solids（SS） obviously increase to 61.7%, 81.3%, and 77.1%, respectively, in comparison with the values of 35.6%, 50.2%, and 49.3% without effluent recirculation. But the improvement of TP removal is slight, only from 42.3% to 48.9%. The variations of NH4-N, dissolved oxygen（DO） and oxidation-reduction potential（ORP） of inflow and outflow reveal that the adoption of effluent recirculation is benefi- cial to the formation of oxide environment in wetland. The exponential relationships with excellent correlation coefficients （R2 〉0.93） are found between the removal rates of NH4-N and BOD5 and the recirculation rates. With recirculation the pH value of the outflow decreases as the alkalinity is consumed by gradually enhanced nitrification process. When recirculation rate is kept constant 100%, the ambient temperature appears to affect NH4-N removal, but does not have significant influence on BOD5 removal.

Performance of hybrid constructed wetland systems for treating septic tank effluent

The integrated wetland systems were constructed by combining horizontal-flow and vertical-flow bed, and their purification efficiencies for septic tank effluent were detected when the hydraulic retention time （HRT） was 1 d, 3 d, 5 d under different seasons. The results showed that the removal efficiencies of the organics, phosphorus were steady in the hybrid systems, but the removal efficiency of total nitrogen was not steady due to high total nitrogen concentration in the septic tank effluent. The average removal rates of COD （chemical oxygen demand） were 89%, 87%, 83%, and 86% in summer, autumn, winter and spring, respectively, and it was up to 88%, 85%, 73%, and 74% for BOD5 （5 d biochemical oxygen demand） removal rate in four seasons. The average removal rates of TP （total phosphorous） could reach up to 97%, 98%, 95%, 98% in four seasons, but the removal rate of TN （total nitrogen） was very low. The results of this study also indicated that the capability of purification was the worst in winter. Cultivating with plants could improve the treated effluent quality fTom the hybrid systems. The results of the operation of the horizontal-flow and vertical-flow cells （hybrid systems） showed that the removal efficiencies of the organics, TP and TN in horizontal-flow and vertical-flow cells were improved significantly with the extension of HRT under the same season. The removal rate of 3 d HRT was obviously higher than that of 1 d HRT, and the removal rate of 5 d HRT was better than that of 3 d HRT, but the removal efficiency was not very obvious with the increment of HRT. Therefore, 3 d HRT might be recommended in the actual operation of the hybrid systems for economic and technical reasons.

Constructed Wetland Systems as a Methodology for the Treatment of Wastewater in Bucaramanga Industrial Park

Effluent discharges from municipal, industrial, and agricultural activities constitute major sources of pollution on land and water bodies. During the 1990s, large-scale application of Constructed Wetlands (CWs) as a remediation option drew much attention globally from the public and green groups alike. The most common application of CWs is for flow management in river system and little is documented on using CWs for treating polluted river water. This article goes beyond constructed wetlands as a stand-alone methodology to propose an integrated remediation system incorporating constructed wetlands in Bucaramanga Industrial Park S.A., Santander (Colombia), which will form part of an innovation park. In addition to pollution abatement, the project is projected to provide other environmental benefits to the entire Oro River Sub-basin. Other benefits of the project include mitigation of environmental impacts, improvement in water quality, landscape amenity, as well as tourism and recreational benefits.

Performance of different macrophytes in the decontamination of and electricity generation from swine wastewater via an integrated constructed wetland-microbial fuel cell process

Plants constitute a major element of constructed wetlands(CWs).In this study,a coupled system comprising an integrated vertical flow CW(IVCW) and a microbial fuel cell(MFC) for swine wastewater tre atment was developed to research the effects of macrophytes commonly employed in CWs,Canna indica,Acorus calamus,and Ipomoea aquatica,on decontamination and electricity production in the system.Because of the different root types and amounts of oxygen released by the roots,the rates of chemical oxygen demand(COD) and ammonium nitrogen(NH4^+-N) removal from the swine wastewater differed as well.In the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,the COD removal rates were 80.20%,88.07%,84.70%,and 82.20%,respectively,and the NH4+-N removal rates were 49.96%,75.02%,70.25%,and 68.47%,respectively.The decontamination capability of the Canna indica system was better than those of the other systems.The average output voltages were 520±42,715±20,660±27,and 752±26 mV for the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,respectively,and the maximum power densities were 0.2230,0.4136,0.3614,and0.4964 W/m^3,respectively.Ipomoea aquatica had the largest effect on bioelectricity generation promotion.In addition,electrochemically active bacteria,Geobacter and Desulfuromonas,were detected in the anodic biofilm by high-throughput sequencing analysis,and Comamonas(Proteobacteria),which is widely found in MFCs,was also detected in the anodic biofilm.These results confirmed the important role of plants in IVCW-MFCs.

Effect of artificial aeration on the performance of vertical-flow constructed wetland treating heavily polluted river water

Three lab-scale vertical-flow constructed wetlands （VFCWs）, including the non-aerated （NA）, intermittently aerated （IA） and continuously aerated （CA） ones, were operated at different hydraulic loading rates （HLRs） to evaluate the effect of artificial aeration on the treatment efficiency of heavily polluted river water. Results indicated that artificial aeration increased the dissolved oxygen （DO） concentrations in IA and CA, which significantly favored the removal of organic matter and NH4＋-N. The DO grads caused by intermittent aeration formed aerobic and anoxic regions in IA and thus promoted the removal of total nitrogen （TN）. Although the removal efficiencies of CODEr, NH4＋-N and TN in the three VFCWs all decreased with an increase in HLR, artificial aeration enhanced the reactor resistance to the fluctuation of pollutant loadings. The maximal removal efficiencies of CODEr, NH4＋-N and total phosphorus （TP） （i.e., 81%, 87% and 37%, respectively） were observed in CA at 19 cm/day HLR, while the maximal TN removal （i.e., 57%） was achieved in IA. Although the improvement of artificial aeration on TP removal was limited, this study has demonstrated the feasibility of applying artificial aeration to VFCWs treating polluted river water, particularly at a high HLR.

Toxic effect of perfluorooctane sulfonate on plants in vertical-flow constructed wetlands

Per-and polyfluoroalkyl substances(PFASs)can be taken up and bioaccumulated in plants,but the toxic mechanisms of PFASs on wetland plants are still unclear.In present study,the toxic influences of perfluorooctane sulfonate(PFOS)on Eichhornia crassipes(E.crassipes)and Cy perus alternifolius(C.alternifolius)in a vertical-sub surface-flow constructed wetland were evaluated.The results showed that E.crassipes was more tolerant to PFOS stress than C.alternifolius,and the growth and chlorophyll synthesis of the two plants were promoted by low concentration(<0.1 mg/L)of PFOS,and the chlorophyll synthesis was inhibited by high concentration(10 mg/L)of PFOS but the growth did not change obviously.The catalase activity and malondialdehyde content in the leaves of the two plants increased,peroxidase activity decreased under exposure to high concentrations of PFOS,and superoxide dismutase activity did not change.Under PFOS stress,the membrane of plant leaves and the cell structure of the two wetland plants were destroyed,and the mitochondrial contour of root cells became incomplete.Tanscriptomic analysis showed that the expression levels of genes related to cell wall formation,the cell apoptosis pathway,material synthesis,and metabolism in the plants were changed by PFOS.Analysis in fluorogenic quantitative real time polymerase chain reaction(RT-qPCR)also confirmed that the photosynthesis system of E.crassipes was inhibited,while that of C.alternifolius was promoted.

Decontamination efficiency and root structure change in the plant-intercropping model in vertical-flow constructed wetlands

Subtropical climatic conditions can contribute to the death of the aerial parts of constructed wetland plants in winter. This presents a barrier to the widespread application of constructed wetland and is an issue that urgently needs to be solved. Three contrasting experi- ments, the plant-intercropping model （A）, the warm- seasonal plant model （B）, and the non-plant model （C）, were studied in terms of their efficiency in removing pollutants, and the change in root structure of plants in the plant-intercropping model within the vertical-flow con- structed wetlands. The results indicate that model A was able to solve the aforementioned problem. Overall, average removal rates of three pollutants （CODcr, total nitrogen （TN） and total phosphorous （TP）） using model A were significantly higher than those obtained using models B and C （P 〈 0.01）. Moreover, no significant differences in removal rates of the three pollutants were detected between A and B during the higher temperature part of the year （P〉 0.05）. Conversely, removal rates of the three pollutants were found to be significantly higher using model A than those observed using model B during the lower temperature part of the year （P 〈 0.01）. Furthermore, the morphologies and internal structures of plant roots further demonstrate that numerous white roots, whose distribution in soil was generally shallow, extend further under model A. The roots of these aquatic plants have an aerenchyma structure composed of parenchyma cells, therefore, roots of the cold-seasonal plants with major growth advantages used in A were capable of creating a more favorable vertical-flow constructed wetlands media- microenvironment. In conclusion, the plant-intercropping model （A） is more suitable for use in the cold environment experienced by constructed wetland during winter.

Modeling the effects of constructed wetland on nonpoint source pollution control and reservoir water quality improvement

This article describes the integrated modeling approach for planning the size and the operation of constructed wetlands for maximizing retention of nonpoint source pollutant loads and reservoir water-quality improvement at a catchment scale. The experimental field-scale wetland systems （four sets, 0.88 ha each） have been in operation since 2002, where water depth was maintained at 30-50 cm and hydraulic loading rate was at 6.3-18.8 cm/day. The wetland system was found to be adequate for treating polluted stream water with stable removal efficiency even during the winter. The integrated modeling system （modified-BASINS） was applied to the Seokmoon estuarine reservoir watershed and calibrated with monitoring data from constructed wetland, stream, and reservoir. The calibrated integrated modeling system estimated that constructing wetlands on 0.5% （about 114 ha） of the watershed area at the mouth of reservoir could reduce 11.61% and 13.49% of total external nitrogen and phosphorus loads, respectively. It also might improve the nitrogen and phosphorus concentration of the reservoir by 9.69% and 16.48%, respectively. The study suggested that about 0.1%-1.0% of the watershed area should be allocated for constructed wetland to meet specified water-quality standards for the estuarine reservoir at the polder area where land use planning is relatively less complicated.

Removal,distribution and plant uptake of perfluorooctane sulfonate(PFOS)in a simulated constructed wetland system

A vertical-flow constructed wetland(VFCW)was used to treat simulated domestic sewage containing perfluorooctane sulfonate(PFOS).The removal rate of PFOS in the domestic sewage was 93%–98%,through soil adsorption and plant uptake,suggesting that VFCWs can remove PFOS efficiently from wastewater.The removal of PFOS in the VFCW was dependent on soil adsorption and plant uptake;moreover,the percentage of soil adsorption was 61%–89%,and was higher than that of the plants uptake(5%–31%).The absorption capacity of Eichhornia crassipes(E.crassipes)(1186.71 mg/kg)was higher than that of Cyperus alternifolius(C.alternifolius)(162.77 mg/kg)under 10 mg/L PFOS,and the transfer factor of PFOS in E.crassipes and C.alternifolius was 0.04 and 0.58,respectively,indicating that PFOS is not easily translocated to leaves from roots of wetland plants;moreover,uptake of PFOS by E.crassipes was more than that of C.alternifolius because the biomass of E.crassipes was more than that of C.alternifolius and the roots of E.crassipes can take up PFOS directly from wastewater while C.alternifolius needs to do so via its roots in the soil.The concentration of 10 mg/L PFOS had an obvious inhibitory effect on the removal rate of total nitrogen,total phosphorus,chemical oxygen demand,and ammonia nitrogen in the VFCW,which decreased by 15%,10%,10%and 12%,respectively.Dosing with PFOS in the wastewater reduced the bacterial richness but increased the diversity in soil because PFOS stimulated the growth of PFOS-tolerant strains.

复合垂直流人工湿地基质理化性质对nirS和nirK型反硝化菌多样性的影响

深入研究复合垂直流人工湿地基质理化性质及其对相关脱氮反硝化微生物的影响,可为解析人工湿地污水处理及提高脱氮效率提供理论依据。2020年12月采集贵州喀斯特地区复合垂直流人工湿地4口池(一级垂直流下行池、一级垂直流上行池、二级垂直流下行池、二级垂直流上行池)的基质样品,用Illumina高通量测序技术获得反硝化功能基因序列,分析其种群组成和多样性特征,并采用冗余分析揭示反硝化菌群落与基质理化性质之间的相关性。结果表明,复合垂直流人工湿地中4口池的基质理化性质存在显著差异;pH在4口池中均呈中性,溶解氧(DO)呈先下降后升高趋势,下行池的基质电导率(EC)均比上行池要高;总氮(TN)、总磷(TP)含量随着人工湿地梯级呈显著下降趋势,未出现厌氧现象;NO_(3)^(-)-N和NH_(4)^(+)-N含量在二级垂直流下行池中大量积累并达到峰值。在多样性分析中,nirS、nirK型反硝化菌丰度随着人工湿地梯级呈先降低后升高的趋势,多样性随人工湿地级数逐渐降低,且下行池丰度多样性显著高于上行池。基质中nirS型反硝化菌共5门9属,nirS型为6门14属,变形菌门是nirS、nirK型反硝化菌群的共同优势菌门,相对丰度为55.36%~65.72%、30.06%~45.66%。nirS、nirK型反硝化菌共有OTUs数分别为392、245,并与反硝化菌群OTUs数目趋势一致,从多角度表明nirS型反硝化菌群丰度明显高于nirK型,且共有OTUs占有率高达41.6%和41.7%,表明各级池中反硝化菌群相似度较高。冗余分析表明基质中nirS和nirK反硝化菌群的构建主要受pH、NH4+-N、DO、TP、TN影响,且nirS型对pH、nirK型对NH4+-N的响应更为强烈。

硫自养脱氮技术在农村污水处理中的应用研究

分别在一体化污水处理设备和人工湿地中装填硫自养反硝化填料和硫铁矿来强化脱氮效果。在一体化污水处理设备中,创新地将硫自养反硝化填料填充于PP球壳中并悬挂置于后段缺氧池,设备TN去除值在3.96~15.58 mg/L之间,平均去除值为8.52 mg/L,其中后段缺氧池对TN的去除量占总去除量的76.3%。人工湿地在HRT较短条件下,TN去除率最高可达到83.8%,TN去除量最高达到10.52 mg/L,且抗冲击负荷能力较强,自我恢复速度较快,规律性的pH变化和实际进出水检测都说明人工湿地发生了硫自养反硝化作用。两段硫自养反硝化强化脱氮后出水达到且优于GB 18918—2002一级A标准。

复合构建湿地运行初期理化性质及氮的变化

研究了在间歇式进水条件下 ,复合构建湿地系统对氮的去除效果 ,阐述了温度、溶氧、pH等理化因子变化的原因。实验初期 ,系统尚处于不稳定时期 ,对N的去除不够理想。随着系统运转逐步步入稳定状态 ,对KN、NH+ 4 N、NO-2 N有明显的去除效果 ,平均去除率分别为 5 0 %、6 6 %和 71%。硝化 -反硝化作用是氨氮去除的主要途径。从总体上看 ,有植物系统中硝态氮的出水含量较对照系统高 ,说明间歇式进水以及植物的存在都有利于硝化作用的发生。实验发现 ,复合构建湿地在冬季仍能较好地改善水质 ,是一种有效的水链管理对策 。

复合人工湿地运行2a净化水禽污水效果

通过构建表流与潜流湿地相结合的复合人工湿地来处理水禽污染的富营养化水体,研究了运行2年的复合人工湿地对化学需氧量(CODcr)、总悬浮物(TSS)、全氮(TN)和全磷(TP)的去除作用。研究表明,复合人工湿地对CODcr、TSS、TN和TP的2年平均去除率分别为42.64%、72.64%、31.69%和52.67%;对污染物CODcr、TSS、TN、TP的去除效果随复合人工湿地运行时间变化而有所差异。在表流湿地中,夏季对CODcr的平均去除率要优于秋季,秋季潜流湿地和复合人工湿地对CODcr的平均去除率优于夏季。在对TSS的平均去除率,表流湿地、潜流湿地和复合人工湿地都表现为秋季优于夏季。表流湿地对TN的平均去除率表现为夏季显著优于秋季。在对TP的平均去除率中,表流湿地和复合人工湿地都表现为秋季优于夏季,而潜流湿地对TP的去除效果表现为秋季低于夏季。通过对进出水中的TP、TN、TSS和CODcr进行回归分析发现,除复合人工湿地和表流湿地区TSS的进水质量浓度与出水质量浓度无明显相关性外,其他复合人工湿地不同构建类型进出水的CODcr、TN、TP质量浓度均存在显著线性相关关系。该研究可为我国北方地区应用复合人工湿地处理富营养化水体提供理论依据。

组合家庭人工湿地系统处理北方农村生活污水

该文对组合家庭人工湿地系统处理北方农村生活污水进行了为期10个月的试验研究(包括冬季)。湿地床上部铺设了0.5m的生物质保温层,使在冬季最低气温-15℃的低温下,系统温度仍维持在7℃以上,保证了系统的正常运行。结果表明,化学需氧量(CODcr)、生化需氧量(BOD5)、氨氮(NH3-N)、总磷(TP)、总固体悬浮物(TSS)和浊度的平均去除率分别为93.0%、96.0%、88.4%、87.7%、97.0%和89.6%,出水体积质量平均值分别为36.0、11.8、3.5、0.6、3.8mg/L和浊度9.1NTU,满足国家排放二级标准。组合家庭人工湿地系统是一种适合农村分散式家庭污水处理的新途径。

复合垂直流人工湿地污水处理系统硝化与反硝化作用

研究了复合垂直流人工湿地各基质层的硝化与反硝化菌数量以及硝化与反硝化作用强度 .结果表明 ,基质中硝化菌数量为 7 5× 10 3 ～ 1 1× 10 5MPN·g-1,反硝化菌数量为 7 5× 10 6～ 1 1× 10 7MPN·g-1.硝化作用强度为 0 0 1～ 6 35 μg·(g·d) -1,反硝化作用强度为 3 37～ 4 19μg·(g·d) -1.沿水流方向硝化菌数量和硝化作用强度明显降低 ,其变化趋势呈显著正相关 (r =0 96 6 1,p <0 0 0 1) .反硝化菌数量和反硝化作用强度比较稳定 ,沿水流方向略有上升 ,其变化趋势呈显著正相关 (r =0 772 2 ,p <0 0 2 5 ) .沿水流方向 ,硝化作用与反硝化作用强度变化呈显著负相关 (r=- 0 9776 ,p <0 0 0 1) ,这与人工湿地的溶氧状况和污水中氨氮含量较高相一致 .

复合垂直流构建湿地基质酶活性与污水净化效果

构建湿地是 2 0世纪 70年代兴起的处理污水的生态工程 ,由于其具有建造、运行和日常管理费用低廉 ,处理效果稳定 ,且适用面广 ,越来越受到世界各国的重视。这种污水处理技术在发展中国家有着十分广泛的应用前景。本文研究与揭示了复合垂直流构建湿地基质中的磷酸酶和脲酶活性及与污水净化效果的关系 :1不同类型湿地基质酶活性不同 ,甚至不同月份的酶活性也不相同。2不同深度基质中的酶活性是不相同的。 3基质磷酸酶的活性与复合垂直流构建湿地对污水中总磷 ( TP)、无机磷 ( IP)以及化学需氧量 ( CODCr)的去除率有很显著的相关关系。 4脲酶的活性与凯氏氮 ( KN)的去除率相关性极显著。这些为利用酶活性强度作为评价净化效果和挑选合适湿地植物的指标提供了理论依据。