Research Progress on Application of Constructed Wetland in Wastewater Treatment in China

Constructed wetlands as a wastewater eco-treatment technology has devel-oped for decades. Combining wastewater-treatment with water recycle in an efficient way, it plays an important role in water body restoration and ecological construction. Constructed wetlands with unique advantages have attracted intensive attention since it developed, and have been widely used in treatment of domestic sewage, industrial wastewater, and mine wastewater. In this paper, we summarized the clas-sification, composition, combination, operation mode and pol utant removal mecha-nism of constructed wetlands, as wel as the research progress on the application of constructed wetland in wastewater treatment at home and abroad. In addition, in view of the problems of using constructed wetlands to treat wastewater in China, corresponding solutions were put forward, including setting up system construction standards for constructed wetlands, developing the regulatory and enhancing tech-niques of nitrogen and phosphorus removal, and taking advantage of the unique features of constructed wetlands to improve and restore ecological environment.

Application of Constructed Wetlands on Wastewater Treatment for Aquaculture Ponds

A group of constructed wetlands （CWs） were applied to the recirculating aquaculture system. This study assessed the performance of CWs in treating the aquaculture wastewater, examined the water quality condition of aquaculture ponds and the growth and the survival rate of ＂target＂ species （Ictalurus punctatus and Megalobrama amblycephala）. The results showed that CWs were effective on reducing the concentrations of 5-day biochemical oxygen demand （BOD5, at 70.5%）, total suspended solids （TSS, at 81.9%）, chlorophyll a （Chl-a, at 91.9%）, ammonium （NH4^＋, at 61.5%） and nitrate nitrogen （NOa-N, at 68.0%）. Effect of CWs on phosphate （PO43 -P） removal was relatively lower （at 20.0%）. The concentrations of BODs, TSS, Chl-a, NH4^＋ and TN, TP in the recirculating culture pond were significantly lower than that in the control pond（ p〈0.05 ）. CWs could help to increase total yield, survival rate of the ＂target＂ species and significantly decrease feed conversion ratio （ p〈0.05 ）.

Wastewater treatment performance and microbial community structure in the constructed wetland under double-pressure of low temperature and Ag NPs exposure

To investigate the effects of silver nanoparticles(Ag NPs)and low temperature double-pressure on the wastewater treatment efficacy and the microbial community structure of constructed wetlands,a pilot-scale vertical flow constructed wetland was set up to treat synthetic wastewater under laboratory conditions.By measuring the effluent concentration of ammonia nitrogen(NH_(4)^(+)-N),total nitrogen(TN),total phosphorus(TP),chemical oxygen demand(COD),and the diversity,richness,and community structure of microorganisms of the upper and lower soil layers in the wetland,the nutrient removal effect of the constructed wetland and the changes in the microflora of the soil layer were studied.The results reveal that the correlation coefficients between the removal rates of TN and NH_(4)^(+)-N and the temperature are 0.463 and 0.692,respectively,indicating a significant positive correlation.From the warm to the cold season,both the diversity and richness of microorganisms in the lower soil layer of wetlands are inhibited under the double-pressure of Ag NPs and low temperature,and the abundances of the denitrogenation functional bacteria such as Candidatus nitrososphaera,Sulfuritalea,Anaeromyxobacter,Candidatus solibacter,Nitrospira,and Zoogloea are altered.Low temperature and Ag NPs exposure can thus affect the wastewater treatment performance of constructed wetlands,possibly because of the seasonal changes of the microflora.

Electricity generation during wastewater treatment by a microbial fuel cell coupled with constructed wetland

A membrane-less constructed wetland microbial fuel cell （CW-MFC） is constructed and operated under continuous flow with a hydraulic retention time （HRT） of 2 d. Fed with glucose, the CW-MFC generates a stable current density of over 2 A/m3 with a resistor of 1 kΩ and has a chemical oxygen demand （COD） removal efficiency of more than 90% after the startup of 2 to 3 d. A series of systems with the electrode spacings of 10, 20, 30 and 40 cm are compared. It is found that the container with the electrode spacing of 20 cm gains the highest voltage of 560 mV, the highest power density of 0. 149 W/m 3, and the highest Coulombic efficiency of 0.313%. It also has the highest COD removal efficiency of 94. 9%. In addition, the dissolved oxygen （DO） concentrations are observed as the lowest level in the middle of all the CW-MFC reactors. The results show that the more COD is removed, the greater power is generated, and the relatively higher Coulombic efficiency will be achieved. The present study indicates that the CW-MFC process can be used as a cost-effective and environmentally friendly wastewater treatment with simultaneous power generation.

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.

Study and Application of Constructed Wetlands in Wastewater Treatment of Aquaculture

As a new type of sewage treatment technology,constructed wetland has high water purification ability and is receiving wider and wider attention. This paper comprehensively introduced the concept,building,classification,wastewater treatment mechanism of constructed wetland and its application in wastewater treatment of aquaculture.

A pilot study on wastewater treatment by constructed wetlands with high dissolved oxygen vegetated submerged bed

It is necessary to treat wastewater in a more environment-friendly fashion.Vegetated submerge bed constructed wetlands (CWs) has become the focus of the research in this field. In this paper, the overall capacity of vertical subsurface flow CWs in the removal of pollutants from municipal wastewater effluent and the effects of the depth of vegetated submerged bed on the removal efficiency were studied. The results showed that the COD, NH+4-N and TN could be removed effectively in the vertical subsurface flow CWs and the best efficiency was obtained from the 10 cm run. However, the TP removal was not effective in all vertical CWs. A shallow depth of vegetated submerged bed may avoid the risk of substrate plugging effectively, and may keep a stable operation of CWs in long term. Decreasing the depth of vegetated submerged bed could create a sufficient aerobic circumstance in which the concentration of DO (dissolved oxygen) in bed was super saturation.

Performance of a Horizontal Flow Constructed Reed Bed Filter for Municipal Wastewater Treatment: The Case Study of the Prototype Installed at Gaston Berger University, Saint-Louis, Senegal

In Saint-Louis, Senegal, a constructed wetland with horizontal flow reed beds (FHa and FHb) has demonstrated significant efficacy in treating municipal wastewater. Analyzing various treatment stages, the system showed only a slight temperature variation, from an influent average of 26.3°C to an effluent of 24.7°C. Electrical conductivity decreased from 1331 mS/cm to 974.5 mS/cm post-primary treatment, with suspended solids (SS) dramatically reduced from 718.9 mg/L to 5.7 mg/L in the final effluent. Biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) saw a notable decrease, from initial levels of 655.6 mg/L and 1240 mg/L to 2.3 mg/L and 71.3 mg/L, respectively. Nitrogenous compounds (N-TN) and phosphates () also decreased significantly, indicating the system’s nutrient removal capacity. Microbiological analysis revealed a reduction in fecal coliforms from 7.5 Ulog/100ml to 1.8 Ulog/100ml and a complete elimination of helminth eggs. The presence of Phragmites and Typha was instrumental in enhancing these reductions. The system’s compliance with the Senegalese standards for disposal into natural environments, WHO recommendations for unrestricted water reuse in irrigation, and the European legislation for water reuse was established. The effluent quality met the stringent criteria for various classes of agricultural reuse, illustrating the system’s potential for sustainable water management. This wetland model presents a robust solution for water-stressed regions, ensuring environmental protection while supporting agricultural needs. The study calls for ongoing research to further refine the system for optimal, reliable wastewater treatment and water resource sustainability.

Experiences with Constructed Wetland Systems in Korea

In spite of the low temperature during the winter season and the high land environment, the wetland treatment system is gaining popularity in Korea because of its lower construction cost and simplicity in operation and maintenance. Many different types of wetland treatment systems have been built during the last 10 years, among which the free water surface wetland has been predominant. Most of the large-scale systems are government projects for improving the water quality of the streams flowing into the estuary dikes and reservoirs. The covering plants used in this system are different in different areas but cattails and reeds or their combinations are common. Constructed wetlands in Korea can be characterized by their shallow depths and short hydraulic residence times. There is no established flow pattern and configuration rules for constructing wetlands, but many efforts have been made with a view to improving their ecological function. Flow control is the most difficult problem in designing a riverbed or riparian wetland. There have been scores of flow rate control devices developed for wetlands, but none of them guarantee wetlands’ safety against flooding. In earlier wetland construction, the building materials were mainly soil. Recently, strong and durable building materials such as rocks, gravel beds, concrete and steel are used at vulnerable places to protect them from erosion. Our investigation indicated that the wetland system would be an appropriate technology because it is not only cheaper to construct, but also requires less maintenance work. However, we suffer from the reduced effectiveness in performance during the winter. We need to evaluate the partial treatment accomplished during 6 to 7 months per year.

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.

Performance of Phragmites Australis and Cyperus Papyrus in the treatment of municipal wastewater by vertical flow subsurface constructed wetlands

The use of constructed wetlands to treat municipal wastewater reduces energy consumption and therefore economic costs,as well as reduces environmental pollution.The purpose of this study was to compare the purification capacity of domestic wastewater using two species of plants sown in subsurface constructed wetlands with vertical flow built on a small scale that received municipal wastewater with primary treatment.The species used were Phragmites Australis and Cyperus Papyrus.For this purpose,a constant flow of 0.6 m3 day-1 was fed from the primary lagoon to each of the two wetlands built on a pilot scale with continuous flow.Each unit was filled with granite gravel in the lower part and with silicic sand in the upper part of different granulometry,the porosity of the medium was 0.34,with a retention time of 1.12 days and a hydraulic load rate of 0.2 m day-1.To analyze the purification capacity of wastewater,physical,chemical and biological parameters were monitored during three months.Samples were taken at the entrance and exit in each experimental unit.The results obtained in the experimental tests for the two species of plants,indicated that the Cyperus Papyrus presented a greater capacity of pollutants removal as biochemical oxygen demand (80.69%),chemical oxygen demand (69.87%),ammoniacal nitrogen (69.69%),total phosphorus (50%),total coliforms (98.08%) and fecal coliforms (95.61%).In the case of Phragmites Australis retains more solids.The species with greater efficiency in the treatment of municipal wastewater for this study was Cyperus Papyrus.

Constructed wetlands for wastewater treatment in cold climate--A review

Constructed wetlands（CWs） have been successfully used for treating various wastewaters for decades and have been identified as a sustainable wastewater management option worldwide.However,the application of CW for wastewater treatment in frigid climate presents special challenges.Wetland treatment of wastewater relies largely on biological processes,and reliable treatment is often a function of climate conditions.To date,the rate of adoption of wetland technology for wastewater treatment in cold regions has been slow and there are relatively few published reports on CW applications in cold climate.This paper therefore highlights the practice and applications of treatment wetlands in cold climate.A comprehensive review of the effectiveness of contaminant removal in different wetland systems including：（1） free water surface（FWS） CWs;（2） subsurface flow（SSF） CWs;and（3） hybrid wetland systems,is presented.The emphasis of this review is also placed on the influence of cold weather conditions on the removal efficacies of different contaminants.The strategies of wetland design and operation for performance intensification,such as the presence of plant,operational mode,effluent recirculation,artificial aeration and in-series design,which are crucial to achieve the sustainable treatment performance in cold climate,are also discussed.This study is conducive to further research for the understanding of CW design and treatment performance in cold climate.

Landscape Construction of Wetlands for Wastewater Treatment

By reviewing the development of wetlands used for wastewater treatment both in China and other countries, the definition and classification of wetlands for wastewater treatment are put forward and the guiding principle in the construction of wetlands for wastewater treatment is discussed in this paper. In view of the process of wastewater treatment of the wetlands, appropriate landscape structure of wetlands used for wastewater treatment is proposed which includes three sections as pre-treatment, wetlands and posttreatment. The discussion as well as conclusion is made upon the approaches of landscape construction of these three parts.

Performance assessment and microbial diversity of two pilot scale multi-stage sub-surface flow constructed wetland systems

This study assessed the performance and diversity of microbial communities in multi-stage sub-surface flow constructed wetland systems（CWs）. Our aim was to assess the impact of configuration on treatment performance and microbial diversity in the systems. Results indicate that at loading rates up to 100 g BOD5/（m2·day）, similar treatment performances can be achieved using either a 3 or 4 stage configuration. In the case of phosphorus（P）, the impact of configuration was less obvious and a minimum of 80% P removal can be expected for loadings up to 10 g P/（m2·day） based on the performance results obtained within the first16 months of operation. Microbial analysis showed an increased bacterial diversity in stage four compared to the first stage. These results indicate that the design and configuration of multi-stage constructed wetland systems may have an impact on the treatment performance and the composition of the microbial community in the systems, and such knowledge can be used to improve their design and performance.

Removal of herbicide 2,4-D using constructed wetlands at pilot scale

Herbicide 2,4-D is one of the most widely used in the world.In this way,its presence on different bodies of water has been reported.In this paper the efficiency of horizontal-subsurface flow constructedwetlands for 2,4-D removal in aqueous solutions was assessed.Wetlands were constructed using fiberglass,and grown with Phragmites australis.The influent consisted of synthetic wastewater under different 2,4-D and glucose initial concentrations.Results indicated that,under the evaluated experimental conditions,2,4-D extent of removal was between 71.0 and 99.0%.In general,it can be noted that an increase in the herbicide concentration reduces the removal efficiency,probably due to a toxic effect on the biological component.On the other hand,the influent dissolved organic carbon(DOC)initial concentration had a significant effect on the removal of both,the herbicide and the organic matter content in the system,demonstrating that this parameter has a significant effect on this kind of biological methods for water treatment.Finally,it can be concluded that constructed wetlands are a viable alternative for the treatment of wastewater contaminated with the herbicide 2,4-D.

Performance of wastewater sludge ecological stabilization

In this article, wastewater sludge ecological stabilization （WWSES） was presented for sludge dewatering, mineralization, and stabilization, as well as for percolate treatment. Two years of pilot scale experimental results indicated that sludge volatile solid, Wiphenyltetrazolium chloride （TTC）-dehydrogenase activity （DHA）, and moisture content as indicators showed the process and degree of sludge stabilization. The observation on dewatering process showed that dried sludge reached a content of 20%-50% total solid after two years of system operation. Sludge TTC-DHA in the first year was obviously lower than that of the second year, and TTC-DHA tended to decrease with an increase in the drying time of the sludge. Total nitrogen, total phosphorus, and organic contents of sludge decreased gradually from the top to the bottom of dried sludge layer. In comparison with natural stands on stands treated with sewage sludge, individual shoot was significantly higher, and coarse protein, coarse fat, and coarse fiber contents in reed roots, stems, and leaves in the system were higher than that of wild reed, especially coarse protein contents of reed roots in the system （7.38%） were obviously higher than that of wild reeds （3.29%）.

Variations in Uptake and Translocation of Copper, Chromium and Nickel Among Nineteen Wetland Plant Species

An experiment was carried out to investigate the variations in metal uptake and translocation among 19 wetland plant species in small-scale plots of constructed wetland using artificial wastewater containing 2.0 mg L^-1 copper （Cu）, 1.0 mg L^-1 chromium （Cr）, and 2.0 mg L^-1 nickel （Ni）. More than 97% of Cu, Cr, and Ni were removed from the wastewater by the wetland plant species. There were more than ]00-fold differences in the metal accumulation and more than ten-fold differences in the metal concentrations among the 19 plant species. These plants accumulated as high as 8.8% of Cu, 20.5% of Cr, and 14.4% of Ni when they were grown in the wetland soaked with the wastewater. Several plant species were found to be highly capable of accumulating one, two or all the three metals. The results indicated considerable variations in the metal removal abilities through phytoextraction among the 19 wetland plant species. It can be concluded that the selection of appropriate plant species in constructed wetland can be crucial for the improvement of metal removal efficiency of the wetland system.

人工湿地-微生物燃料电池中电极研究进展

【目的】近年来,人工湿地(CW)与微生物燃料电池(MFC)相耦合,形成了一种新型的生物电化学系统——人工湿地-微生物燃料电池(CW-MFC),具有出色的污染物降解和生物发电性能。本文旨在总结电极的特性和应用,介绍不同电极材料对系统的影响,最后对其未来的研究方向提出展望。【方法】结合国内外最新的研究成果。【结果】总结了电极的功能特性和应用,介绍了不同电极材料在废水处理过程中的性能差异以及对发电效率的影响,并对其未来的研究方向提出了展望,为CW-MFC的技术发展作进一步参考。【结论】CW-MFC是一种具有广泛应用前景的生物电化学系统。未来研究方向包括优化电极材料、提高系统运行效率、降低成本等方面。同时,还需要加强在实际应用中的研究,以推动该技术在环境保护和能源领域的应用。

A Lab-scale Study on the Routes of Nitrogen and Phosphorus Removal in Gravel-based Reed Bed Systems

The removal of ammonia and phosphorus from an artificial wastewater was studied in two lab-scale reed beds.During batch and continuous operations,it was found that ammonia was removed from the wastewater via a two-step process,sorption inside bed matrices followed by nitrification into nitrite and nitrate.Rapid decrease in the concentration of ammonia in the artificial wastewater was observed during the batch operation,whereas during the continuous operation,which lasted for 39 days,the percentage removal of ammonia decreased gradually with time before stabilizing at around 20%.The efficiency of phosphorus removal exhausted rapidly during the continuous operation,from 39% on the first day of operation to virtually zero after only 5 days.The results suggest that sorption(which may include ion exchange,adsorption,and biomass assimilation) serves as an initial step to remove ammonia and phosphorus from the wastewater,prior to any microbial transformations.

清洁生产视角下人工湿地与造纸废水处理工艺的融合研究

废水处理是制浆造纸企业日常运营过程中的重要工作,其工艺水平甚至可以直接决定制浆造纸企业是否可以实现绿色可持续发展。以制浆造纸产业的清洁生产为基本出发点,对现有造纸废水处理工艺的现状和难题进行总结,尝试将人工湿地与造纸废水处理的工艺进行融合,并对融合后的废水处理工艺进行测试。结果表明:将人工湿地与造纸废水处理工艺进行融合,可以很好地实现废水无害化处理,综合处理效果优于传统的制浆造纸废水物化处理。