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1
Kennedy, Gavin, and Tatiana Mayer. "Natural and Constructed Wetlands in Canada: An Overview." Water Quality Research Journal 37, no. 2 (May 1, 2002): 295–325. http://dx.doi.org/10.2166/wqrj.2002.020.
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Abstract A review of freshwater wetland research in Canada was conducted to highlight the importance of these ecosystems and to identify wetland research needs. Both natural and constructed wetland systems are discussed. Natural wetlands are an important part of the Canadian landscape. They provide the habitat for a broad variety of flora and fauna and contribute significantly to the Canadian economy. It is estimated that the total value derived from consumptive and non-consumptive activities exceeds $10 billion annually. The past decades have witnessed the continued loss and degradation of wetlands in Canada. In spite of recent protection, Canadian wetlands remain threatened by anthropogenic activities. This review shows that more research on fate and transport of pollutants from urban and agricultural sources in wetland systems is needed to better protect the health and to assure the sustainability of wetlands in Canada. Furthermore, improved knowledge of hydrology and hydrogeochemistry of wetlands will assure more effective management of these ecosystems. Lastly, better understanding of the effect of climate change on wetlands will result in better protection of these important ecosystems. Constructed wetlands are man-made wetlands used to treat non-point source pollution. The wetland treatment technology capitalizes on the intrinsic water quality amelioration function of wetlands and is emerging as a cost-effective, environmentally friendly method of treating a variety of wastewaters. The use of wetland technology in Canada is, however, less common than in the U.S.A. A number of research needs has to be addressed before the wetland treatment technology can gain widespread acceptance in Canada. This includes research pertaining to cold weather performance, including more monitoring, research on design adaptation and investigation of the effects of constructed wetlands on wildlife.
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Xia, Hong Xia, and Qi Hong Zhu. "Purification Effect of Self-Aeration Constructed Wetlands on COD." Advanced Materials Research 690-693 (May 2013): 1122–26. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.1122.
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Aimed at the issue of dissolved oxygen concentration insufficiency in regular constructed wetlands, shale hollow bricks are adopted to build self-aeration constructed wetlands, to increase the oxygen supply capacity in the system. The experimental result indicates that DO concentration in self-aeration constructed wetlands is 0.1mg/L higher than that in artificially intensified aeration wetlands, and the removal rate for COD reaches over 85%,which is about 2% higher than that of artificial aeration wetlands. This shows that the built self-aeration constructed wetland system can increase oxygen supply capacity in the wetland, and increase the purification efficiency of the wetland system for COD in wastewater.
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Chen, Fang, and Qiang Yao. "Application of Constructed Wetland to Rural Domestic Wastewater Treatment in China." Advanced Materials Research 1073-1076 (December 2014): 1011–14. http://dx.doi.org/10.4028/www.scientific.net/amr.1073-1076.1011.
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Constructed wetland is a new wastewater treatment technology. It not only is more effective in wastewater treatment, but also has good eco-landscapes value. According to the characteristics of domestic wastewater discharge in rural, constructed wetlands is a key technology to solving this problem in China. Application of constructed wetland to Chinese rural domestic wastewater treatment was reviewed in this paper. On this basis, the issues in the application of constructed wetland encountered, and future trends are discussed. On the one hand, constructed wetlands were prone to clogging and low nitrogen removal efficiency. On the other hand, some existing constructed wetlands were abandoned due to poor maintenance and management. Therefore, in order to play better the role of wastewater treatment, anti-blocking ability and denitrification efficiency of constructed wetlands should be improved. Meanwhile, the maintenance and management of constructed wetlands should be strengthened. Application of constructed wetlands in the rural area provides a strong guarantee for sustainable development of rural economy.
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Rash, Jonathan K., and Sarah K. Liehr. "Flow Pattern Analysis of Constructed Wetlands Treating Landfill Leachate." Water Science and Technology 40, no. 3 (August 1, 1999): 309–15. http://dx.doi.org/10.2166/wst.1999.0176.
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Three series of tracer studies were performed on three constructed wetlands at the New Hanover County Landfill near Wilmington, North Carolina, USA. One vegetated free water surface wetland (FWS-R), one vegetated subsurface flow wetland (SSF-R), and one unvegetated control subsurface flow wetland (SSF-C) were studied. A conservative tracer, lithium chloride, was used to study the chemical reactor behavior of these wetlands under normal operating conditions. Results indicated that short-circuiting is quite common in SSF wetlands, while FWS wetlands are well-mixed and not as subject to short-circuiting. These results were obtained from and reinforced with tracer measurements at interior points in these wetlands, analysis of residence time distributions from two different formulations, and the construction of residence volume distributions. The short-circuiting in the SSF wetlands can be attributed to the following: (1) Vertical mixing is inhibited by a combination of physical barriers and density gradients caused by rainfall and runoff dilution of the upper layer; and (2) Leachate is drawn from the bottom of the wetland, causing it to further prefer a flow path along the bottom.
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Hadidi, Luna Al. "CONSTRUCTED WETLANDS A COMPREHENSIVE REVIEW." International Journal of Research -GRANTHAALAYAH 9, no. 8 (September 13, 2021): 395–417. http://dx.doi.org/10.29121/granthaalayah.v9.i8.2021.4176.
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Constructed wetlands are wastewater treatment systems composed of one or more treatment cells in a building designed and constructed to provide wastewater treatment. Constructed wetlands are classified into two types: free water surface (FWS) wetlands (also known as surface flow wetlands) closely resemble natural wetlands in appearance because they contain aquatic plants that are rooted in a soil layer on the bottom of the wetland and water flows through the leaves and stems of plants. Subsurface flow wetlands (SSF) or known as a vegetated submerged bed (VSB) systems do not resemble natural wetlands because they have no standing water. They contain a bed of media (such as crushed rock, small stones, gravel, sand, or soil) that has been planted with aquatic plants. When properly designed and operated, wastewater stays beneath the surface of the media, flows in contact with the roots and rhizomes of the plants, and is not visible or available to wildlife. Constructed wetlands are an appropriate technology for areas where inexpensive land is generally available and skilled labor is less available. In this paper, a comprehensive review covered types, characteristics, design variation and considerations, limitations, and the advantages and disadvantages of constructed wetlands.
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Sukhla, Prof Saurabh M., Mr Khatik Sufiyan Jameel, Mr Prasad Abhishek Ramesh, Mr Satpute Nikhil Bhairavnath, Mr Pawar Pravin Surendra, Mr Mitthe Mayur Ramnath, Prof Prashant G. Chavan, and Prof Pravin S. Chavanke. "Wastewater Treatment Using Constructed Wetland System." International Journal for Research in Applied Science and Engineering Technology 10, no. 5 (May 31, 2022): 1303–6. http://dx.doi.org/10.22214/ijraset.2022.42463.
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Abstract: Natural wetland such as marshes ,swamps and bogs protect water quality . constructed or artificial wetland system mimic the treatment that occurs in natural wetlands by rellyilng on plants and a combination of naturally occurring biological , chemical and physical processes to remove pollutants from water . As of 1999,there were more than 500 constructed wetland in Europe and 600 in north America . constructed wetland are a less energy intensive and more environmentally sound way of treating waste water and conserving potable water . The first single family home constructed wetland in southern Nevada was completed Eighth years ago. A constructed wetland (CW) is an artificial wetland to treat sewage, greywater, stormwater runoff or industrial wastewater. It may also be designed for land reclamation after mining, or as a mitigation step for natural areas lost to land development constructed wetlands also act as a biofilter and/or can remove a range of pollutants (such as organic matter, nutrients, pathogens, heavy metals) from the water. Constructed wetlands are designed to remove water pollutants such as suspended solids, organic matter and nutrients (nitrogen and phosphorus).
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King, Andrew C., Cynthia A. Mitchell, and Tony Howes. "Hydraulic tracer studies in a pilot scale subsurface flow constructed wetland." Water Science and Technology 35, no. 5 (March 1, 1997): 189–96. http://dx.doi.org/10.2166/wst.1997.0195.
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Current design procedures for Subsurface Flow (SSF) Wetlands are based on the simplifying assumptions of plug flow and first order decay of pollutants. These design procedures do yield functional wetlands but result in over-design and inadequate descriptions of the pollutant removal mechanisms which occur within them. Even though these deficiencies are often noted, few authors have attempted to improve modelling of either flow or pollutant removal in such systems. Consequently the Oxley Creek Wetland, a pilot scale SSF wetland designed to enable rigorous monitoring, has recently been constructed in Brisbane, Australia. Tracer studies have been carried out in order to determine the hydraulics of this wetland prior to commissioning it with settled sewage. The tracer studies will continue during the wetland's commissioning and operational phases. These studies will improve our understanding of the hydraulics of newly built SSF wetlands and the changes brought on by operational factors such as biological films and wetland plant root structures. Results to date indicate that the flow through the gravel beds is not uniform and cannot be adequately modelled by a single parameter, plug flow with dispersion, model. We have developed a multiparameter model, incorporating four plug flow reactors, which provides a better approximation of our experimental data. With further development this model will allow improvements to current SSF wetland design procedures and operational strategies, and will underpin investigations into the pollutant removal mechanisms at the Oxley Creek Wetland.
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Li, Hong, Hong Hu Zeng, and Yan Peng Liang. "Removal of Organochlorine Pesticides in Constructed Wetlands." Applied Mechanics and Materials 692 (November 2014): 40–43. http://dx.doi.org/10.4028/www.scientific.net/amm.692.40.
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Organochlorine pesticides have had a wide and long history of applications in many countries around the world, which cause serious environmental problems. Constructed wetlands are considered an effective means of removal of organochlorine pesticides. This study describes the constructed wetland and applications of organochlorine pesticides contamination in constructed wetlands, and focuses on purification for organochlorine pesticides of microorganisms and plants in constructed wetlands. Then discussed constructed wetlands removal influence factors of organochlorine pesticides. And put forward some recommendations in research.
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Persson, J., N. L. G. Somes, and T. H. F. Wong. "Hydraulics Efficiency of Constructed Wetlands and Ponds." Water Science and Technology 40, no. 3 (August 1, 1999): 291–300. http://dx.doi.org/10.2166/wst.1999.0174.
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Constructed ponds and wetlands are widely used in urban design to serve a number of functions including stormwater management. The design of constructed wetlands for stormwater management involves a number of multi-disciplinary inputs. Fundamental to their sustainable operation are the proper control of the hydrologic regime of the wetland and optimal flow hydrodynamics within the wetland. Many ofthe problems encountered in constructed wetlands can be minimised or avoided by good engineering design principles. Poor wetland hydrodynamics are often identified as a major contributor to wetland management problems. Ponds and wetlands with a high hydraulic efficiency are expected to promote full utilisation ofthe available detention storage and near plug flow conditions. The shape and layout of urban ponds and wetlands are often varied to suit the landscape and to satisfy aesthetic requirements as an urban water feature. These can be achieved while maintaining an effective stormwater treatment outcome if steps are taken to ensure that the hydrodynamic behaviour of the system is not severely compromised. A consistent measure is required to allow the effects of design features to be evaluated against this criterion. This paper introduces a new measure for hydraulic efficiency that combines existing measures of flow uniformity and effective volume. Case studies are presented on the use of this measure to assess the effects of different pond and wetland shapes, locations of inlet and outlet, botanical layouts and basin morphology on the flow hydrodynamics.
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Kadlec, R. H., and D. L. Hey. "Constructed Wetlands for River Water Quality Improvement." Water Science and Technology 29, no. 4 (February 1, 1994): 159–68. http://dx.doi.org/10.2166/wst.1994.0181.
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The Des Plaines River Wetlands Demonstration Project has reconstructed four wetlands in Wadsworth, Illinois, USA. The river drains an agricultural and urban watershed, and carries a non-point source contaminant load of sediment, nutrients and agricultural chemicals. Up to 40% of the average stream flow is pumped to the wetlands, and allowed to return from the wetlands to the river through control structures followed by vegetated channels. Native wetland plant species have been established, ranging from cattail, bulrushes, water lilies, and arrowhead to duckweed and algae. Pumping began in the summer of 1989, and has continued during the ensuing spring, summer and fall periods. The experimental design provides for different hydraulic loading rates, ranging from 5 to 60 cm/week. Intensive wetland research began in late summer 1989, and continues to present. Detailed hydrology is measured for each wetland. Sediment removal efficiencies ranged from 86–100% for the four cells during summer, and from 38–95% during winter. Phosphorus removal efficiencies ranged from 60–100% in summer and 27–100% in winter. The river contains both old, persistent and modem, degradable agricultural chemicals. The principal modem pollutant is atrazine, of which the wetlands remove approximately half. The project is successfully illustrating the potential of constructed wetlands for controlling non-point source pollution at an intermediate position in the watershed.
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Hunt, P. G., and M. E. Poach. "State of the art for animal wastewater treatment in constructed wetlands." Water Science and Technology 44, no. 11-12 (December 1, 2001): 19–25. http://dx.doi.org/10.2166/wst.2001.0805.
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Although confined animal production generates enormous per-unit-area quantities of waste, wastewater from dairy and swine operations has been successfully treated in constructed wetlands. However, solids removal prior to wetland treatment is essential for long-term functionality. Plants are an integral part of wetlands; cattails and bulrushes are commonly used in constructed wetlands for nutrient uptake, surface area, and oxygen transport to sediment. Improved oxidation and nitrification may also be obtained by the use of the open water of marsh-pond-marsh designed wetlands. Wetlands normally have sufficient denitrifying population to produce enzymes, carbon to provide microbial energy, and anaerobic conditions to promote denitrification. However, the anaerobic conditions of wetland sediments limit the rate of nitrification. Thus, denitrification of animal wastewaters in wetlands is generally nitrate-limited. Wetlands are also helpful in reducing pathogen microorganisms. On the other hand, phosphorus removal is somewhat limited by the anaerobic conditions of wetlands. Therefore, when very high mass removals of nitrogen and phosphorus are required, pre- or in-wetland procedures that promote oxidation are needed to increase treatment efficiency. Such procedures offer potential for enhanced constructed wetland treatment of animal wastewater.
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Li, Han, Radmila Petric, Zinah Alazzawi, Jake Kauzlarich, Rania H. Mahmoud, Rasheed McFadden, Niklas Perslow, et al. "Four Years Continuous Monitoring Reveals Different Effects of Urban Constructed Wetlands on Bats." Land 10, no. 10 (October 14, 2021): 1087. http://dx.doi.org/10.3390/land10101087.
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Proactive artificial wetland constructions have been implemented to mitigate the loss of wetlands and their ecosystem services. As wetlands are habitats for bats, short-term (one or two years) studies find that constructed wetlands can immediately increase local bat activity and diversity. However, it is not clear how constructed wetlands affect bats through time while the wetlands are aging. We collected four years of continuous bat acoustic monitoring data at two constructed wetlands in an urban park in Greensboro, NC, USA. We examined bat activity and community composition patterns at these wetlands and compared them with reference sites in the city. With four years of data, we found that the effects of constructed wetlands were both habitat- and species-specific. The wetland in forests significantly increased bat activity, while the wetland in the open grass altered bat community composition. Specifically, in terms of species, we found that over time, constructed wetlands no longer attracted more big brown, silver-haired, or evening bats than control sites while the wetlands aged, highlighting the need to study broadly how each bat species uses natural and artificial wetlands. We emphasize the importance of long-term monitoring and the periodical evaluation of wildlife conservation actions.
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Higgins, James, and Michael Maclean. "Technical Note — The Use of a Very Large Constructed Sub-Surface Flow Wetland to Treat Glycol-Contaminated Stormwater from Aircraft De-Icing Operations." Water Quality Research Journal 37, no. 4 (November 1, 2002): 785–92. http://dx.doi.org/10.2166/wqrj.2002.053.
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Abstract All of the pollutants found in stormwater runoff at airports, including surface and aircraft de-icing/anti-icing glycols, can be treated and removed to low levels in well-designed sub-surface flow (SSF) constructed wetland systems. There are two common forms of constructed wetlands used for pollution control: those where water flows over the surface among wetland plants (free water surface or marsh type wetlands); and SSF types where the wastewater flows below the normally dry surface of a gravel substrate in which the wetland plants grow. SSF wetlands have no open water to attract waterfowl and are particularly suitable for use at airports. Of the glycol used at Edmonton International Airport (EIA), 80 to 90% eventually entered surface runoff. Edmonton International Airport's operator, the Edmonton Regional Airports Authority (Edmonton Airports) evaluated a number of glycol management options, including constructed wetlands. As a result, a very large SSF wetland system was installed to handle glycol-contaminated stormwater. This paper reviews results of a feasibility study carried out to define design parameters and scale up kinetics for this wetland system, the detailed design that resulted, the SSF wetland's construction, and the start-up of the Edmonton facilities in August of 2000. It also compares the Edmonton wetland system with a similar facility at Heathrow Airport in the United Kingdom.
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Gopal, Brij. "Natural and Constructed Wetlands for Wastewater Treatment: Potentials and Problems." Water Science and Technology 40, no. 3 (August 1, 1999): 27–35. http://dx.doi.org/10.2166/wst.1999.0130.
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Wetlands are being considered increasingly important for wastewater treatment because of the ability of many wetland plants to absorb large amounts of nutrient and a variety of toxic substances. The paper highlights the physical, chemical and biological processes which contribute to the improvement of water quality, and the distinction between natural and constructed wetlands. The impacts of long-term wastewater disposal on the biotic changes, reduction in treatment efficiency, and wetland processes such as production of trace gases, are pointed out. Constraints in using wetlands, for wastewater treatment, such as poor understanding of the natural wetland functions and responses of native plants and animals to wastewater, particularly in developing countries, are briefly discussed. It is suggested that while the possibilities for using constructed wetlands based on native species for small communities are explored, greater emphasis should be laid on the restoration of lost and degraded wetlands, especially the river floodplains, lake littorals and coastal wetlands, which can help check pollution from non-point sources.
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Bao, Zhen Bo, Deng Chao Jin, and Hong Jun Teng. "Constructed Wetlands Sewage Treatment Technology Purification Mechanism and Influence Factors." Advanced Materials Research 518-523 (May 2012): 3003–6. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.3003.
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Constructed wetlands are new sewage treatment technology, which have advantages of good decontamination effect, low operating costs and easy maintenance. Base on analysis of constructed wetlands composition and purification mechanism, the constructed wetlands purification influence factors are summarized, and the problems and solutions of constructed wetlands are pointed out. Carrying out in-depth study on constructed wetlands design, operational control and maintenance management to improve comprehensive benefits of wetland sewage purification technology, have great practical significance and far-reaching social significance.
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Saxena, Shalini. "EFFICACY OF PHRAGMITE KARKA PLANT IN CONSTRUCTED WETLAND SYSTEM." International Journal of Research -GRANTHAALAYAH 3, no. 9SE (September 30, 2015): 1–5. http://dx.doi.org/10.29121/granthaalayah.v3.i9se.2015.3177.
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Wetlands, either constructed or natural, offer a cheaper and low-cost alternative technology for wastewater treatment. A constructed wetland system that is specifically engineered for water quality improvement as a primary purpose is termed as a ‘Constructed Wetland Treatment System’ (CWTS). In the past, many such systems were constructed to treat low volumes of wastewater loaded with easily degradable organic matter for isolated populations in urban areas. However, widespread demand for improved receiving water quality, and water reclamation and reuse, is currently the driving force for the implementation of CWTS all over the world. Recent concerns over wetland losses have generated a need for the creation of wetlands, which are intended to emulate the functions and values of natural wetlands that have been destroyed. Natural characteristics are applied to CWTS with emergent macrophyte stands that duplicate the physical, chemical and biological processes of natural wetland systems. The number of CWTS in use has very much increased in the past few years. The use of constructed wetlands is gaining rapid interest. Most of these systems cater for tertiary treatment from towns and cities. They are larger in size, usually using surface-flow system to remove low concentration of nutrient (N and P) and suspended solids. However, in some countries, these constructed wetland treatment systems are usually used to provide secondary treatment of domestic sewage for village populations. These constructed wetland systems have been seen as an economically attractive, energy-efficient way of providing high standards of wastewater treatment by the help of Phragmite karka plant.
Typically, wetlands are constructed for one or more of four primary purposes: creation of habitat to compensate for natural wetlands converted for agriculture and urban development, water quality improvement, flood control, and production of food and fiber.
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Boutilier, Leah, Rob Jamieson, Robert Gordon, and Craig Lake. "Transport of Lithium Tracer and E. coli in Agricultural Wastewater Treatment Wetlands." Water Quality Research Journal 43, no. 2-3 (May 1, 2008): 137–44. http://dx.doi.org/10.2166/wqrj.2008.017.
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Abstract Agricultural waste must be managed effectively to protect surface and groundwater resources, as well as human health. Constructed wetlands can provide a low-cost environmentally acceptable method for the treatment of agricultural wastewater. An ionic tracer (Lithium chloride [LiCl]) and a biotracer (a naladixic acid-resistant strain of Escherichia coli) were injected into six pilot-scale constructed wetlands treating dairy wastewater: three surface-flow (SF) wetlands and three subsurfaceflow (SSF) wetlands. Each wetland was 3.9-m long and 1.7-m wide. Residence time distribution functions were calculated for each wetland to investigate the hydraulic behaviour of each system during winter and summer conditions. During the summer study, the mean residence times for SF wetlands 2, 4, and 6 were 12, 16, and 14 days, respectively, while the mean residence time for SSF wetlands 1, 3, and 5 were 23, 18, and 22 days, respectively. The longitudinal dispersion coefficients were in the order of 10-6 m2 s-1 for each wetland during the summer and winter. The mean residence time for SF wetlands 2, 4, and 6 during the winter study were 8, 10, and 10 days, respectively, while the mean residence time for SSF wetlands 1, 3, and 5 were 8, 9, and 10 days, respectively. E. coli effluent peaks often occurred prior to Li peaks, suggesting that bacteria may be motile within the wetland environment. This study suggests that dispersion is an important mass transport process in both SF and SSF wetlands. Long-term operation of SF and SSF treatment wetlands may cause reduced retention times and treatment efficiency due to organic matter accumulation and channelling. Cold winter temperatures may also increase the survival of bacteria within treatment wetland systems, decreasing the wetland's ability to reduce bacteria concentrations during the winter months.
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Saxena, Shalini. "CLEAN DEVELOPMENT MECHANISM AND CARBON CYCLING OF SEWAGE WASTE BY CONSTRUCTED WETLANDS." International Journal of Research -GRANTHAALAYAH 10, no. 4 (May 17, 2022): 209–15. http://dx.doi.org/10.29121/granthaalayah.v10.i4.2022.4517.
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Wetlands, either constructed or natural, offer a cheaper and low-cost alternative technology for wastewater treatment. A constructed wetland system that is specifically engineered for water quality improvement as a primary purpose is termed as a ‘Constructed Wetland Treatment System’ (CWTS). In the past, many such systems were constructed to treat low volumes of wastewater loaded with easily degradable organic matter for isolated populations in urban areas. However, widespread demand for improve in water quality, and water reclamation and reuse, is currently the driving force for the implementation of CWTS all over the world. Recent concerns over wetland losses have generated a need for the creation of manmade wetlands, which are intended to emulate the functions and values of natural wetlands that have been destroyed. Natural characteristics are applied to CWTS with emergent macrophyte stands that duplicate the physical, chemical and biological processes of natural wetland systems. The number of CWTS in use has very much increased in the past 50 years. The use of constructed wetlands is gaining rapid interest. Most of these systems cater for tertiary treatment from towns and cities. They are larger in size, usually using surface-flow system to remove low concentration of nutrient (N and P) and suspended solids. However, in some countries, these constructed wetland treatment systems are usually used to provide secondary treatment of domestic sewage for village populations. These constructed wetland systems have been seen as an economically attractive, energy-efficient way of providing high standards of wastewater treatment.
Typically, wetlands are constructed for one or more of four primary purposes: creation of habitat to compensate for natural wetlands converted for agriculture and urban development, water quality improvement, flood control, and production of food and fiber (constructed aquaculture wetlands). In present research the sewage water is treated by constructing Horizontal sub – surface flow constructed wetland, and reed grass is used as vegetation to treat waste and make the sewage waste water clean.
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Messer, Tiffany L., Trisha L, Moore, Natalie Nelson, Laurent Ahiablame, Eban Z. Bean, Chelsie Boles, Sonja L. Cook, Steven G. Hall, John McMaine, and Derek Schlea. "Constructed Wetlands for Water Quality Improvement: A Synthesis on Nutrient Reduction from Agricultural Effluents." Transactions of the ASABE 64, no. 2 (2021): 625–39. http://dx.doi.org/10.13031/trans.13976.
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Abstract. Excess nutrients from agricultural settings contribute to surface water and groundwater impairment. Constructed wetlands have been widely used for water quality protection in various agricultural systems. We used a synthesis approach to document the performance of constructed wetlands for nutrient removal from a range of landscapes and geographic regions with the following objectives: (1) review the current use of constructed wetlands in agricultural applications, (2) summarize the nutrient removal efficiency of constructed wetlands, and (3) identify the geographic usage and costs associated with constructed wetlands. We reviewed over 130 publications and reports to characterize nutrient removal performance for the following types of agricultural effluents: cropland surface and subsurface drainage, and wastewater from livestock production, greenhouse, aquaculture, and hydroponic systems. Data from the reviewed studies indicate that constructed wetlands are efficient in protecting water quality in agricultural production settings. However, differences in constructed wetland characteristics reported by the studies suggest that standards are needed to ensure nutrient removal goals are met based on wetland design. Researchers should consider including basic performance parameters for constructed wetlands in published reports, including influent and effluent concentrations, hydraulic retention time, hydraulic loading rate, watershed to treatment wetland ratios, and plant species and relative cover. Future studies are needed to explore cost-benefit analyses to assess the feasibility and potential promotion of wetland incentive programs in various geographic regions and watershed nonpoint-source pollution goals for using these systems in agricultural settings. Keywords: Agricultural wastewater, Agricultural water quality, Aquaculture, Cropland runoff, Greenhouse, Hydroponic, Livestock, Review, Subsurface, Treatment wetland.
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Mæhlum, T., P. D. Jenssen, and W. S. Warner. "Cold-climate constructed wetlands." Water Science and Technology 32, no. 3 (August 1, 1995): 95–101. http://dx.doi.org/10.2166/wst.1995.0130.
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This paper outlines design considerations for constructed wetlands with horizontal subsurface flow treating domestic wastewater in cold climates of northern latitudes. Particular attention is devoted to the use of a filter medium with high phosphorus adsorption capacity. Experience from two Norwegian multistage systems consisting of an aerobic pretreatment step followed by constructed wetland units indicates purification processes are nearly the same during winter and summer seasons, with quite high removal of organic matter (COD, BOD), phosphorus and nitrogen.
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Ling, Zhen, Ju Rui Yang, and Zhe Nai Lu. "Research on the Effect of Sewage Concentration on Treatment Efficiency of Constructed Wetlands." Advanced Materials Research 356-360 (October 2011): 1510–15. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.1510.
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By changing the surface flow(SF) and subsurface flow (SSF)constructed wetlands inflow water total nitrogen (TN) concentrations, with 6 plant species (purple leaf canna, water onion, water hyacinth, water celery, calamus, reed) in comparative experiments, comparative analysis of the 6 different SF and SSF constructed wetlands treatment rate with the variation of the concentration obtained in the 6 different plant SF and SSF constructed wetlands, the optimal concentration theory, theory of optimal removal rate, the actual optimal concentration, the actual optimal removal rate and TN maximum daily processing load. The results showed that: in the 6 different plant of SF and SSF constructed wetlands for TN removal efficiency decreased as the concentration increased, different plant, different levels of treatment rate reduction, and removal value of SSF was lower than SF. Purple leaf canna removal reduced the minimum, SF processing rate decreased 17.07%, SSF dropped 15.94%; Reed removal rate decreased obviously, the SF processing rate decreased 20.86%, SSF dropped 18.2%. Meanwhile, according to the result of the experiment, the maximum TN daily remove quantity in the six species of plants of SF constructed wetland was 547.20 g•m-2•d-1;in SSF constructed wetland was 577.60 g•m-2•d-1. Wetland as an efficient, low consumption of new sewage treatment technology has been widely accepted, especially in total nitrogen (TN) in the application phase for the people attention. Study found that of nitrogen removal efficiency of constructed wetlands and external factors, a wetland substrate, plant species, microbes, sewage load, residence time, nitrogen in sewage and water distribution methods[1]. For the wastewater load on the removal of wetlands, Zhou Yaohua so that low concentration of domestic sewage (20% water) on the ground flora as a whole more effective than a higher concentration of the decontamination wastewater (100% effluent) better overall removal [2]. Cui Fang water residence time in the study of the impact of decontamination capability of wetlands that the reed wetland water CODcr, TP, NH3-N concentration had little effect on the removal, and TN concentrations had a significant effect on the removal, removal of only 27% [3], Yuan Donghai and others that wetlands on the initial concentration of pollutants in wastewater have certain requirements, low pollution case, the constructed wetland was better; higher concentration of pollutants cases, the purification efficiency dropped [4]. Effluent decontamination effect on the wetland will have some impact, at present, domestic and international research to a single species of plants, mainly a single type of wetland, considering the different plants, different types of comparative study of wetlands was less. By changing SF and SSF constructed wetlands, inflow water TN concentrations, with 6 plant speciesin comparative experiments, comparative analysis of the 6 different plants of SF and SSF constructed wetlands treatment rate with the variation of the concentration obtained in 6 different plant SF and SSF constructed wetlands, the optimal concentration theory, theory of optimal removal rate, the actual optimal concentration, optimal removal rate and the actual TN maximum daily processing load, optimizing the hydraulic conditions of wetlands. Research on the promotion of artificial wetland technology, further development of eco-environmental rehabilitation has a certain significance
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King, Susan K., and Stephen C. Richter. "Reproductive Ecology and Nesting Site Characteristics of Four-Toed Salamanders (Hemidactylium scutatum) in Natural and Constructed Upland-Embedded Wetlands on the Appalachian Plateau, Kentucky." Diversity 14, no. 11 (November 18, 2022): 995. http://dx.doi.org/10.3390/d14110995.
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Many forested freshwater wetlands have been altered or destroyed, and wetlands are constructed to offset loss. However, they do not always replace the function of natural wetlands. It is important to understand how features of the habitat differ between types of wetlands and whether constructed wetlands provide an adequate habitat for species adapted to natural wetlands. Our objectives were to measure the characteristics of Four-toed Salamanders’ nesting habitat and determine which factors contribute to the abundance of eggs and nests in natural and constructed upland-embedded wetlands within a ridgetop ecosystem in eastern Kentucky. We located and examined characteristics for 207 nests in twelve wetlands and measured variables at the nest level and at the wetland level. The best predictor of the number of eggs and number of nests was amount of moss at the wetland. These measures of reproductive effort were similar between types of wetlands, but the number of eggs per nest was higher in constructed wetlands and inversely related to amount of moss, highlighting a deficit in nesting habitat. Research of embryonic and larval survival is needed but based on data from other amphibian species in this system, we predict that the survival of Four-toed Salamanders’ larvae is low in constructed wetlands with permanent hydrology. Restoration of constructed wetlands should address the need for moss as nesting substrate and drying of the wetland to reduce the abundance and diversity of predators of larvae.
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Berego, Yohannes Seifu, Solomon Sorsa Sota, Mihret Dananto Ulsido, and Embialle Mengistie Beyene. "Treatment Performance Assessment of Natural and Constructed Wetlands on Wastewater From Kege Wet Coffee Processing Plant in Dale Woreda, Sidama Regional State, Ethiopia." Environmental Health Insights 16 (January 2022): 117863022211427. http://dx.doi.org/10.1177/11786302221142749.
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Constructed wetlands are engineered systems built to use natural processes and remove pollutants from contaminated water in a more controlled environment. The research was an experimental research carried out to assess the effectiveness of natural and constructed wetland systems in the treatment of coffee wastewater. The 2 vertical flow constructed wetland was built. The first wetland covered an area of 132 m2. It has 12 m width and 11 m length. Open space is constructed between 2 constructed wetlands with a dimension of 11 m × 3 m × 1 m. The second wetland was constructed and its function is similar to the first one, from this wetland water is discharged to the river. The construction of the wetland is accomplished by constructing 20 cm wide furrows with a spacing of 30 cm. Vetiver grasses have planted with a spacing of 20 cm intervals. The physicochemical data were recorded, organized, and analyzed using R software (version 4.1) and Microsoft Excel. Data were processed using parametric (one-way ANOVA) and nonparametric (Mann-Whitney’s U test) statistical tests of homogeneity. One-way analysis of Variance (ANOVA) was used to determine the significance of differences in variations in physicochemical variables within the constructed wetland sites. Tukey’s multiple comparisons for differences between means were also assessed. Findings indicated that a natural wetland had a mean influent and effluent of total suspended solids (TSS) of 2190.78 ± 448.46 mg/l and 972.67 ± 234.312 mg/l, respectively. A Mann-Whitney U test revealed that TSS were significantly higher in natural wetland (median = 1551.50) compared to constructed wetland (median = 922.5), U = 676.5, z = −2.435, P = .015, r = .257. Natural wetlands had a mean influent of biological oxygen demand (BOD) was 4277.94 ± 157.02 mg/l, while in the effluent of BOD it was 326.83 ± 112.24 mg/l. While in constructed wetland it was 4192.4 ± 191.3 mg/l, 782.72 ± 507.6 mg/l, and 88.28 ± 20.08 mg/l in influent, middle, and effluent respectively. Average chemical oxygen demand (COD) value at influent in natural wetlands was 8085.61 ± 536.99 mg/l and in the effluent it was 675.33 ± 201.4 mg/l. In constructed wetland, it was found to be 8409.8 ± 592.9, 1372.6 ± 387.94, and 249.0 ± 7.68 for influent, middle, and effluent respectively. Comparatively, the purification efficiency of organic pollutants (TSS, BOD, and COD) of constructed wetlands was better than natural wetlands, whereas natural wetlands had better purification efficiency of nitrogen compounds such as ammonium, nitrite, and nitrate. On average, removal rates for nitrogen compounds were 39.53% and −24.41% for ammonium, 79.44% and 55.4% for nitrite, and 68.90% and 60.6% for nitrate in natural and constructed wetlands respectively, while the phosphate removal rate was 43.17% and 58.7% in natural and constructed wetlands, respectively. A Mann-Whitney U test revealed that there is no significance difference in nitrite, nitrate, ammonium, and phosphate concentration between natural and constructed wetlands( P > .05). Based on these results, both systems of treatment were effective in treating the coffee effluent since most of the values obtained were below the permissible EEPA limits. Even though the constructed wetland treatment plant performed better overall, in comparison, the natural wetlands had better purification efficiency for nitrogen compounds like ammonium, nitrite, and nitrate and the constructed wetlands had better purification efficiency for organic pollutants (TSS, BOD, and COD).
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Mekonnen, Andualem, Seyoum Leta, and Karoli Nicholas Njau. "Wastewater treatment performance efficiency of constructed wetlands in African countries: a review." Water Science and Technology 71, no. 1 (November 28, 2014): 1–8. http://dx.doi.org/10.2166/wst.2014.483.
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In Africa, different studies have been conducted at different scales to evaluate wastewater treatment efficiency of constructed wetland. This paper aims to review the treatment performance efficiency of constructed wetland used in African countries. In the reviewed papers, the operational parameters, size and type of wetland used and the treatment efficiency are assessed. The results are organized and presented in six tables based on the type of wetland and wastewater used in the study. The results of the review papers indicated that most of the studies were conducted in Tanzania, Egypt and Kenya. In Kenya and Tanzania, different full-scale wetlands are widely used in treating wastewater. Among wetland type, horizontal subsurface flow wetlands were widely studied followed by surface flow and hybrid wetlands. Most of the reported hybrid wetlands were in Kenya. The results of the review papers indicated that wetlands are efficient in removing organic matter (biochemical oxygen demand and chemical oxygen demand) and suspended solids. On the other hand, nutrient removal efficiency appeared to be low.
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Berninger, Kati, Jari Koskiaho, and Sirkka Tattari. "Constructed wetlands in Finnish agricultural environments: balancing between effective water protection, multi-functionality and socio-economy / Małe sztuczne zbiorniki wodne w krajobrazie rolniczym Finlandii: ochrona jakości wody na tle wielozadaniowych funkcji tych zbiorników i aspektów socjalno-ekonomicznych." Journal of Water and Land Development 17, no. 1 (December 1, 2012): 19–29. http://dx.doi.org/10.2478/v10025-012-0029-5.
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Abstract This case study summarizes the current knowledge in Finland on the efficiency of constructed wetlands to improve water quality at the same time providing multiple benefits. The efficiency is highly dependent on the wetland’s relative size compared to the upstream catchment area, and on the amount of agricultural land in the upstream catchment. The case study analyses the incentives designed to motivate landowners to construct wetlands in Finland such as the non-productive investment support and the agri-environment payment support for wetland management. Farmers think that the support system is heavy and bureaucratic, and thus the target number of new constructed wetlands is far from being met. Individual projects have been more successful in wetland construction than the official support system. General wetland plans drafted for hotspot areas is an example of enabling factors and strict eligibility rules form one of the barriers of wetland construction identified in this case study. In spite of the criticism of the current wetland incentives, a support system for wetland construction is needed. One option would be to give regional authorities more freedom to select priority areas according to e.g. River Basin Management Plans.
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Pawęska, K., and B. Malczewska. "Nitrogen compounds in drain sewage after constructed wetlands." Water Science and Technology 60, no. 10 (November 1, 2009): 2613–19. http://dx.doi.org/10.2166/wst.2009.620.
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Constructed wetlands, commonly known as ground filters, are well suited mostly for wastewater treatment in areas with no central sewage system. The basic difficulty with exploitation of constructed wetlands is connected with irregular hydraulic overload of its surface. However, irregular wastewater inflow can be reduced by cyclical irrigation which increases efficiency. The unquestionable advantage of the constructed wetlands is inexpensive construction and exploitation as well as low energy consumption. The constructed wetlands also fit very well in surrounding area. The investigation concerned the analysis of two constructed wetlands which are composed of mechanical separation (septic tank) and a filter bed with subsurface flow. The research has been undertaken in a period from July to December 2008, with regard to concentration distribution of nitrogen compounds in municipal sewage after constructed wetlands. The preliminary investigation on constructed wetland which has been exploited for 10 years showed variable removal efficiency of nitrogen compounds. The continuation of the research can indicate the efficiency of wastewater treatment in summer and winter season.
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Worrall, P., K. J. Peberdy, and M. C. Millett. "Constructed wetlands and nature conservation." Water Science and Technology 35, no. 5 (March 1, 1997): 205–13. http://dx.doi.org/10.2166/wst.1997.0199.
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By reference to examples in the UK this paper examines the wildlife potential of reedbed treatment systems, both in their ability to act as pollutant buffers to protect or create downstream wetlands of conservation importance and as wildlife resources in their own right. The constraints of size, structural diversity, pollution stresses and design criteria of constructed wetlands are evaluated in terms of wildlife conservation opportunities, and the more stringent water quality requirements for wildlife functions are discussed. As a case study example, the paper examines in detail the South Finger Reedbed developed by The Wildfowl & Wetlands Trust. This system has been designed with the dual objectives of improving the quality of effluent from a large collection of captive wildfowl in order to buffer sensitive downstream wetlands and of creating a wetland habitat of nature conservation value. The performance of this system, constructed in 1993, indicates good treatment levels, with suspended solids reduction around 80% and BOD generally above 60%. In terms of wildlife performance the system rapidly evolved to support a broad range of vertebrate and invertebrate species. The paper concludes that constructed wetlands for waste water treatment can be designed and managed to achieve optimal wildlife potential if approached from an ecological perspective as opposed to a strictly engineering viewpoint.
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Hamilton, Hugh, Peter G. Nix, and André Sobolewski. "An Overview of Constructed Wetlands as Alternatives to Conventional Waste Treatment Systems." Water Quality Research Journal 28, no. 3 (August 1, 1993): 529–48. http://dx.doi.org/10.2166/wqrj.1993.028.
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Abstract Constructed wetlands are an attractive alternative to conventional wastewater treatment under certain conditions. This review presents background information on wetland treatment and wetland design, and outlines the potential for wetlands to treat water contaminated with organic compounds including hydrocarbons. The major mechanisms that reduce contaminant concentrations in wetlands are sedimentation, filtration, chemical precipitation, microbial interaction and plant uptake. The presence of bacteria in “biofilms” on the enormous plant and detrital surface area in wetlands is fundamental to their ability to degrade complex organic contaminants. There are few examples in the literature of wetlands being used to control organic chemical pollution. However, the very high level of biochemical activity in the water column and upper sediment layer in wetlands, combined with a high degree of ecological resilience, suggests that wetlands can be an attractive low cost, low energy, low maintenance alternative to conventional treatment methods.
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Wang, Han Xi, Jian Ling Xu, Lian Xi Sheng, and Xue Jun Liu. "A Review of Research on Substrate Materials for Constructed Wetlands." Materials Science Forum 913 (February 2018): 917–29. http://dx.doi.org/10.4028/www.scientific.net/msf.913.917.
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Based on the improvements in the decontamination ability and decontamination range of constructed wetlands, this study of constructed wetland substrates was carried out using literature research and comparative meta-analysis. The results show that, for static adsorption, the absorption levels of nitrogen and phosphorus in a given constructed wetland are different. As for hydraulic load, the average removal rate of total nitrogen in wastewater is less than 50%. Compared with single substrates, a combination of substrates is typically superior in terms of the removal rate of sewage pollutants. Adsorption is the key in removing pollutants in constructed wetlands, and modification of the wetland materials is an effective way to improve the decontamination ability of the substrate material. At present, there are areas of potential improvement in the research on the development of new wetland materials for the study of pollutant characteristics, as well as a dearth of modification methods for single and reclaimable wetland substrates in constructed wetlands. These issues should be taken into account in the future studies on constructed wetland materials.
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Shrestha, R. R., R. Haberl, J. Laber, R. Manandhar, and J. Mader. "Application of constructed wetlands for wastewater treatment in Nepal." Water Science and Technology 44, no. 11-12 (December 1, 2001): 381–86. http://dx.doi.org/10.2166/wst.2001.0855.
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Surface water pollution is one of the serious environmental problems in urban centers in Nepal due to the discharge of untreated wastewater into the river-system, turning them into open sewers. Wastewater treatment plants are almost non-existent in the country except for a few in the Kathmandu Valley and even these are not functioning well. Successful implementation of a few constructed wetland systems within the past three years has attracted attention to this promising technology. A two-staged subsurface flow constructed wetland for hospital wastewater treatment and constructed wetlands for treatment of greywater and septage is now becoming a demonstration site of constructed wetland systems in Nepal. Beside these systems, five constructed wetlands have already been designed and some are under construction for the treatment of leachate and septage in Pokhara municipality, wastewater in Kathmandu University, two hospitals and a school. This paper discusses the present condition and treatment performance of constructed wetlands that are now in operation. Furthermore, the concept of the treatment wetlands under construction is also described here. With the present experience, several recommendations are pointed out for the promotion of this technology in the developing countries.
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Zhao, Jun, Jie Zhang, Yu Min Shi, and Xi Wang. "Researches on Constructed Wetlands Running Problems and Treatment Measures in Cold Areas." Advanced Materials Research 955-959 (June 2014): 2050–55. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.2050.
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Constructed wetland is a new type of water treatment technology which has been in great price for its characteristic including low cost, simplicity of operator and landscape value. Climatic environment and temperature has a strong influence to the wetlands which restricts the application of constructed wetlands in the northern cold areas. This paper elaborated the technical progress of constructed wetlands, analyzed the problems in the operational process of constructed wetlands located in low-temperate areas in winter, offered some solving measures which could make sure the wetlands running steadily including interior structure optimization and external insulation.
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Qin, Lu Mei, Hong Hu Zeng, and Yan Peng Liang. "Research Development on Constructed Wetlands." Applied Mechanics and Materials 535 (February 2014): 388–93. http://dx.doi.org/10.4028/www.scientific.net/amm.535.388.
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Constructed wetland is a mode of economical and highly effective system applied in wastewater treatment with special removal mechanism function, which has drawn much attention over the world constantly. On the basis of study from abroad, this article makes the brief induction of removal mechanism, influential factors and combined technique of constructed wetlands, for the further research works were also put forward in the next future.
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Kadlec, Robert H. "Deterministic and stochastic aspects of constructed wetland performance and design." Water Science and Technology 35, no. 5 (March 1, 1997): 149–56. http://dx.doi.org/10.2166/wst.1997.0185.
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Potato processing wastewater contains high concentrations of COD, TSS and TKN. A combination of surface flow wetlands, intermittent vertical flow wetlands, ponds and land application has been used for treatment. This engineered natural system balances irrigation requirements, nitrogen supply and seasonal growth patterns to provide effective year-round operation. A first pilot wetland was operated to determine operability, effectiveness, and plant survival at high COD and nitrogen concentrations. A second pilot system of four wetlands in series was operated to obtain design and operating information. Two surface flow wetlands provided TSS and COD reduction, and ammonified the organic nitrogen. Subsequently, nitrification occurred in the vertical flow wetlands, followed by denitrification in a surface flow wetland. The design target was a balanced nitrogen and irrigation supply for application to crops. Winter storage as used to match the crop application period to the growing season. Both pilot projects met design objectives, and a full scale system has begun operation.
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Langergraber, G. "Simulation of subsurface flow constructed wetlands - results and further research needs." Water Science and Technology 48, no. 5 (September 1, 2003): 157–66. http://dx.doi.org/10.2166/wst.2003.0308.
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Simulation of constructed wetlands has two main tasks: to obtain a better understanding of the processes in constructed wetlands, and to check and optimise existing design criteria. This paper shows simulation results for two indoor pilot-scale constructed wetlands for wastewater and surface water treatment respectively. The results presented and discussed are mainly focussed on the hydraulic behaviour of the constructed wetland systems. In addition results of reactive transport simulations with CW2D are shown. The multi-component reactive transport model CW2D (Constructed Wetlands 2 Dimensional) was developed to model transport and reactions of the main constituents of wastewater (organic matter, nitrogen, and phosphorus) in subsurface flow constructed wetlands. For the pilot-scale constructed wetlands a calibration of the flow model was possible and therefore the results of the reactive transport simulations with CW2D fit the measured data well. The further research needs regarding the simulation of subsurface flow constructed wetlands are discussed.
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Bowles, Mason. "Reviving Urban Ecosystems with Constructed Floating Wetlands." Wetland Science & Practice 36, no. 2 (April 2019): 92–97. http://dx.doi.org/10.1672/ucrt083-233.
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Constructed floating wetlands (CFWs) are a highly efficient ecosystem restoration technology that can be used to improve stormwater quality and reclaim degraded urban shorelines to provide a wide variety of wetland ecosystem services. The concept of CFWs has its origins from naturally-occurring floating wetlands found around the world. They consist of a buoyant substrate that supports wetland plants growing hydroponically, with roots suspended below the water surface. They have the capacity to tolerate fluctuating water levels and variable nutrient loading and can be designed for a number of purposes including to improve water quality, provide bird and wildlife habitat, protect and beautify shorelines, reduce flood risk, sequester carbon and conserve economically important fisheries.
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Chen, Xinyong, Zaifeng Tian, Jing Zhu, Yihong Wu, and Qi Zhao. "Nitrogen removal characteristics of wet–dry alternative constructed wetlands." Green Processing and Synthesis 11, no. 1 (January 1, 2022): 1040–51. http://dx.doi.org/10.1515/gps-2022-0090.
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Abstract Dry–wet alternate constructed wetland is an effective method to remove nitrogen elements in the tail water of sewage treatment plant. According to the reaeration mechanism of wet–dry alternative constructed wetland, the denitrification effect and influence characteristics of the dry–wet alternate constructed wetland on the tail water of sewage treatment plant were studied under low temperature. The results showed that the removal rates of each nitrogen element in the constructed wetland reached 20–40% with the dry–wet alternate time at 10°C. Under the influence of dry–wet alternation of constructed wetland, dissolved oxygen (DO) was significantly correlated with the dry–wet alternation time (p < 0.05), and DO was correlated with each nitrogen element removal rate (p < 0.05), which means constructed wetlands use alternate dry and wet operation, which can significantly affect the content of DO and nitrogen removal efficiency in constructed wetlands, providing a technical basis for regulating the operation effect of constructed wetland ecosystems.
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Graczyk, Thaddeus K., Frances E. Lucy, Leena Tamang, Yessika Mashinski, Michael A. Broaders, Michelle Connolly, and Hui-Wen A. Cheng. "Propagation of Human Enteropathogens in Constructed Horizontal Wetlands Used for Tertiary Wastewater Treatment." Applied and Environmental Microbiology 75, no. 13 (May 1, 2009): 4531–38. http://dx.doi.org/10.1128/aem.02873-08.
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ABSTRACT Constructed subsurface flow (SSF) and free-surface flow (FSF) wetlands are being increasingly implemented worldwide into wastewater treatments in response to the growing need for microbiologically safe reclaimed waters, which is driven by an exponential increase in the human population and limited water resources. Wastewater samples from four SSF and FSF wetlands in northwestern Ireland were tested qualitatively and quantitatively for Cryptosporidium spp., Giardia duodenalis, and human-pathogenic microsporidia, with assessment of their viability. Overall, seven species of human enteropathogens were detected in wetland influents, vegetated areas, and effluents: Cryptosporidium parvum, C. hominis, C. meleagridis, C. muris, G. duodenalis, Encephalitozoon hellem, and Enterocytozoon bieneusi. SSF wetland had the highest pathogen removal rate (i.e., Cryptosporidium, 97.4%; G. duodenalis, 95.4%); however, most of these values for FSF were in the negative area (mean, −84.0%), meaning that more pathogens were discharged by FSF wetlands than were delivered to wetlands with incoming wastewater. We demonstrate here that (i) the composition of human enteropathogens in wastewater entering and leaving SSF and FSF wetlands is highly complex and dynamic, (ii) the removal and inactivation of human-pathogenic microorganisms were significantly higher at the SSF wetland, (iii) FSF wetlands may not always provide sufficient remediation for human enteropathogens, (iv) wildlife can contribute a substantial load of human zoonotic pathogens to wetlands, (v) most of the pathogens discharged by wetlands were viable, (vi) large volumes of wetland effluents can contribute to contamination of surface waters used for recreation and drinking water abstraction and therefore represent a serious public health threat, and (vii) even with the best pathogen removal rates achieved by SSF wetland, the reduction of pathogens was not enough for a safety reuse of the reclaimed water. To our knowledge, this is the first report of C. meleagridis from Ireland.
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Li, Tianjie, Yang Jin, and Yan Huang. "Water quality improvement performance of two urban constructed water quality treatment wetland engineering landscaping in Hangzhou, China." Water Science and Technology 85, no. 5 (February 21, 2022): 1454–69. http://dx.doi.org/10.2166/wst.2022.063.
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Abstract For typical wastewater treatment processes of urban sewage, plants are often noneffective to improve water qualities of lightly polluted domestic sewage, and urban constructed water quality treatment (WQT) wetlands designed with engineering landscape methods are utilized to optimize both water qualities and landscape values in recent years. The research determines the effects of two typical ecological engineering landscaping projects of urban constructed WQT wetlands by analysing their effects of wastewater quality improvements. Differences of water quality indicators (WQI) respectively among different treatment stages of wetlands includes surface flow wetland, vertical flow wetland, floating wetland islands etc., which have been measured and compared. Evaluation of urban constructed WQT wetlands engineering landscaping has been concluded based on comparisons among hydrological indicators and water quality indicators, i.e. pH, DO, NH3-N, CODCr, TP. Removal effects of individual indicators, includes NH3-N, CODCr and TP during different treatment stages have been quantitatively analysed. In accordance with quantitative analysis, benefits and deficiencies of practical landscape design of urban constructed WQT wetlands are concluded. By adapting proper principles in engineering landscaping, environmental and economic benefits can be achieved to create sustainable landscapes of urban constructed WQT wetlands.
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Gui, P., R. Inamori, M. Matsumura, and Y. Inamori. "Evaluation of constructed wetlands by wastewater purification ability and greenhouse gas emissions." Water Science and Technology 56, no. 3 (August 1, 2007): 49–55. http://dx.doi.org/10.2166/wst.2007.517.
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Domestic wastewater is a significant source of nitrogen and phosphorus, which cause lake eutrophication. Among the wastewater treatment technologies, constructed wetlands are a promising low-cost means of treating point and diffuse sources of domestic wastewater in rural areas. However, the sustainable operation of constructed wetland treatment systems depends upon a high rate conversion of organic and nitrogenous loading into their metabolic gaseous end products, such as N2O and CH4. In this study, we examined and compared the performance of three typical types of constructed wetlands: Free Water Surface (FWS), Subsurface Flow (SF) and Vertical Flow (VF) wetlands. Pollutant removal efficiency and N2O and CH4 emissions were assessed as measures of performance. We found that the pollutant removal rates and gas emissions measured in the wetlands exhibited clear seasonal changes, and these changes were closely associated with plant growth. VF wetlands exhibited stable removal of organic pollutants and NH3-N throughout the experiment regardless of season and showed great potential for CH4 adsorption. SF wetlands showed preferable T-N removal performance and a lower risk of greenhouse gas emissions than FWS wetlands. Soil oxidation reduction potential (ORP) analysis revealed that water flow structure and plant growth influenced constructed wetland oxygen transfer, and these variations resulted in seasonal changes of ORP distribution inside wetlands that were accompanied by fluctuations in pollutant removal and greenhouse gas emissions.
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Bhamidimarri, R., A. Shilton, I. Armstrong, P. Jacobson, and D. Scarlet. "Constructed Wetlands for Wastewater Treatment: The New Zealand Experience." Water Science and Technology 24, no. 5 (September 1, 1991): 247–53. http://dx.doi.org/10.2166/wst.1991.0131.
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The use of constructed wetlands which mimic natural marshlands, represents an innovative approach to wastewater treatment. They make use of diverse ecological mechanisms to renovate wastewater. They are inexpensive to construct and operate with minimal energy requirements. Unlike the conventional technologies, wetlands provide low volumetric reaction rates and therefore are suitable for small-scale applications. The majority of constructed wetlands in New Zealand are used for the treatment of domestic wastewaters from small communities for secondary treatment and pathogen removal. There are over 20 constructed wetlands in New Zealand receiving wastewater flow rates ranging from 7.5m3/day to around 4500m3/day. Both surface-flow and subsurface-flow wetlands are used. The performance data from three wetland systems treating septic tank effluents are presented and their treatment efficiences are discussed.
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Peterson, Hans G. "Use of constructed wetlands to process agricultural wastewater." Canadian Journal of Plant Science 78, no. 2 (April 1, 1998): 199–210. http://dx.doi.org/10.4141/p97-142.
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Constructed wetlands are emerging as a serious challenge to conventional wastewater treatment because of lower construction and operating costs, less requirement for trained personnel, more flexibility, and lower susceptibility to variations in waste loading rates. Water quality improvements can be achieved by removal of plant nutrients, such as N and P, organics (natural and manmade) as well as inorganic contaminants. Wetland treatment is now advocated by regulatory agencies and has been determined as the technology of choice by municipalities and industries required to meet stringent discharge regulations. These same regulations have not usually been imposed on the agricultural community, but deteriorating water sources will likely change this regulatory anomaly. Use of this technology in treating agricultural wastewater is still in its infancy with few, although rapidly expanding, applications. This paper aims to highlight different aspects of wetland treatment by exploring its use for the treatment of agricultural run-off as well as wastewater from the agri-food industry. It is concluded that natural wetlands will be quite limited in absorbing agricultural wastewater while constructed wetlands can be designed for optimum pollutant removal. Key words: Constructed wetlands, wastewater treatment, agriculture, food processing, nutrient removal, nitrogen, phosphorus, organics
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Sultana, Mar-Yam, Christos Akratos, Dimitrios Vayenas, and Stavros Pavlou. "Constructed wetlands in the treatment of agro-industrial wastewater: A review." Chemical Industry 69, no. 2 (2015): 127–42. http://dx.doi.org/10.2298/hemind150121018s.
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Due to their simplicity and low operation cost, constructed wetlands are becoming more prevalent in wastewater treatment all over the world. Their range of applications is no longer limited to municipal wastewater but has expanded to the treatment of heavily polluted wastewaters such as agro-industrial effluents. This paper provides a comprehensive literature review of the application of constructed wetlands in treating a variety of agro-industrial wastewaters, and discusses pollutant surface loads and the role of constructed wetland type, prior-treatment stages and plant species in pollutant removal efficiency. Results indicate that constructed wetlands can tolerate high pollutant loads and toxic substances without losing their removal ability, thus these systems are very effective bio-reactors even in hostile environments. Additionally, the review outlines issues that could improve pollutant treatment efficiency and proposes design and operation suggestions such as suitable vegetation, porous media and constructed wetland plain view. Finally, a decision tree for designing constructed wetlands treating agro-industrial wastewaters provides an initial design tool for scientists and engineers.
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Wallace, S., G. Parkin, and C. Cross. "Cold climate wetlands: design and performance." Water Science and Technology 44, no. 11-12 (December 1, 2001): 259–65. http://dx.doi.org/10.2166/wst.2001.0838.
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Constructed wetlands are gaining widespread use as a simple, low cost means of wastewater treatment. Introduction of constructed wetlands technology into the northern United States has been limited by the ability of conventional wetland systems to operate without freezing during the winter. A design approach using subsurface-flow constructed wetlands covered with an insulating mulch layer has been demonstrated to prevent freezing. However, introduction of a mulch layer will affect oxygen transfer rates, pollutant removal performance, and plant establishment. These factors must be addressed for successful application of constructed wetlands technology in cold climates.
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Pankratz, S., T. Young, H. Cuevas-Arellano, R. Kumar, R. F. Ambrose, and I. H. Suffet. "The ecological value of constructed wetlands for treating urban runoff." Water Science and Technology 55, no. 3 (February 1, 2007): 63–69. http://dx.doi.org/10.2166/wst.2007.073.
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The Sweetwater Authority's urban runoff diversion system (URDS) comprises constructed wetlands on a hillside between the town of Spring Valley and the Sweetwater Reservoir, California, USA. The URDS were designed to divert dry-weather and first-flush urban runoff flows from the Sweetwater reservoir. However, these constructed wetlands have developed into ecologically valuable habitat. This paper evaluates the following ecological questions related to the URDS: (1) the natural development of the species present and their growth pattern; (2) the biodiversity and pollutant stress on the plants and invertebrates; and (3) the question of habitat provided for endangered species. The URDS wetlands are comprised primarily of rush (Scirpus spp.) and cattails (Typha spp.). This vegetative cover ranged from 39–78% of the area of the individual wetland ponds. Current analyses of plant tissues and wetland sediment indicates the importance of sediment sorption for metals and plant uptake of nutrients. Analyses of URDS water following runoff events show the URDS wetlands do reduce the amount of nutrients and metals in the water column. Invertebrate surveys of the wetland ponds revealed lower habitat quality and environmental stress compared to unpolluted natural habitat. The value of the wetlands as wildlife habitat is constrained by low plant biodiversity and pollution stress from the runoff. Since the primary Sweetwater Authority goal is to maintain good water quality for drinking, any secondary utilization of URDS habitat by species (endangered or otherwise) is deemed an added benefit.
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Bradley, Jennifer C., and J. M. Zajicek. "Wetland Plants for Wastewater Treatment: A Tremendous Opportunity for Horticulture." HortScience 31, no. 4 (August 1996): 594c—594. http://dx.doi.org/10.21273/hortsci.31.4.594c.
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A current trend in environmental practices concerns using constructed wetlands for wastewater treatment. The ecological values of wetlands have long been known. Wetland plants aid in the treatment of water pollutants by improving conditions for microorganisms and by acting as a filter to absorb trace metals. Wetlands now are being considered for industrial, municipal, and home wastewater treatment. Constructed wetlands are an economical and environmentally sound alternative for treating wastewater. These constructed “cells” are designed to function like natural wetlands. In constructed wetlands, water flow is distributed evenly among plants in a cell where physical, chemical, and biological reactions take place to reduce organic materials and pollutants. Increasing numbers of environmentally conscious homeowners are installing wetland wastewater treatment systems in their backyards with the aid of licensed engineers. This installation is occurring despite of the lack of educational materials to aid in site selection, selection of appropriate plant materials, and long-term maintenance. Traditional wetland plant species currently are being selected and planted in these sites, and the resulting effect is often an unsightly marsh appearance. With increasingly more homeowners opting for this alternative system, a strong need exists for educational materials directed at this audience. Therefore, educational resources that can provide information to the public regarding the benefits of wetland wastewater systems, while promoting aesthetically pleasing ornamental plant species is needed. A hands-on guide for installing constructed wetlands, a home page on the World Wide Web, and an instructional video currently are being developed at Texas A&M Univ. These technologies will be demonstrated and the values, needs, and opportunities available for the horticultural industry in the area of wetland construction will be discussed.
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Zuo, Jin, and Qin Yan. "Recycling Inter-Feed Relationship between Wetlands’ Protective Using and Eco-Town Construction." Advanced Materials Research 361-363 (October 2011): 1085–90. http://dx.doi.org/10.4028/www.scientific.net/amr.361-363.1085.
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As the wetlands has decreased and degenerated badly due to human’s excessive use, it becomes to be a hotspot in international academe’s forefield to resume and rebuild wetlands. Simply opposing protection to using can effectively ease up the stress of wetland’s degradation in a short term, but is disadvantageous to wetland’s sustainable development. This article takes Tianjin Qilihai wetland as example, aiming at its existing problems, sums up two kinds of infection genes – exterior representation and interior motivation, and intensively analyzes the sticking point from three aspects – economic, acknowledgement and mechanism. It suggests that basing on the idea of accretion and co-prosperity, we can divide wetland area into three zone – core zone, buffer zone and experimental zone, and then let the interior dispersive inhabitants and production activities move out to the intensively constructed eco-town. Thus we can make scientific use of wetland’s economical value and promote circumjacent industries’ transformation. Moreover, by the recycling use of water on a model of source separation combined with wetland classification, the quantity of regenerated water would reach 18.25 million cubic meters. By the Low Impact Development (LID) strategies in the control and use of rainfall and flood, the quantity of rainwater for use would reach 8.62 million cubic meters per year. In this way, the wetlands’ ecological conservation would obtain regurgitation-feeding, the construction of eco-town would be organically combined with protection and using of wetlands, and an effective system of wetlands’ sustainable development and using would be established.
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Xing, Chuanjie, Xiangxi Xu, Zhenghe Xu, Rongzhen Wang, and Lirong Xu. "Study on the Decontamination Effect of Biochar-Constructed Wetland under Different Hydraulic Conditions." Water 13, no. 7 (March 25, 2021): 893. http://dx.doi.org/10.3390/w13070893.
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To explore the purification effect of biochar-constructed wetlands on rural domestic sewage, six types of biochar-constructed wetlands were constructed for experiments. Under different hydraulic conditions, the removal effects of each biochar-constructed wetland on chemical oxygen demand, ammonia nitrogen, total nitrogen, and total phosphorus in sewage were analyzed. The results showed that the removal rates of the four types of pollutants in each biochar-constructed wetland first increased and then decreased with the increase in hydraulic retention time, and the optimal hydraulic retention time range was 36–48 h. The highest removal rates of chemical oxygen demand, ammonia nitrogen, total nitrogen, and total phosphorus in the wetland were 97.34 ± 0.84%, 95.44 ± 1.29%, 98.95 ± 0.52%, and 97.78 ± 0.91%, respectively. The chemical oxygen demand (COD) removal rate of each biochar-constructed wetland increased first, then decreased with the increase in hydraulic load, and the optimal hydraulic load was 10 cm/d. The removal efficiency of ammonia nitrogen, total nitrogen, and total phosphorus of each biochar-constructed wetland gradually weakened with the increase in hydraulic load, and the optimal hydraulic load range was between 5 and 10 cm/d. Under these conditions, the highest removal rates of chemical oxygen demand, ammonia nitrogen, total nitrogen, and total phosphorus in the wetland were 92.15 ± 2.39%, 98.32 ± 0.48%, 96.69 ± 1.26%, and 92.62 ± 2.92%, respectively. Coconut shell and shell-constructed wetlands with the highest proportion of biochar in the matrix have the best removal effect on pollutants under different hydraulic conditions, and the wastewater purification effect is stronger, indicating that the addition of biochar is helpful for the removal of pollutants in constructed wetlands.
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Kim, H. C., C. G. Yoon, Y. K. Son, H. P. Rhee, and S. B. Lee. "Effects of open water on the performance of a constructed wetland for nonpoint source pollution control." Water Science and Technology 62, no. 5 (September 1, 2010): 1003–12. http://dx.doi.org/10.2166/wst.2010.333.
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The seasonal performance of four differently configured constructed wetland systems was compared for the treatment efficiency of nonpoint source pollution. Dead plants in the constructed wetlands increased the nitrogen removal rate during winter by providing organic carbon, which is essential for the denitrification process. However, when the wetlands released phosphorus from the dead plants, the removal rate of phosphorus decreased. After seven growing seasons, plant coverage was nearly 100%, and the dissolved oxygen (DO) concentration was lowered to 1.3–5.4 mg/L. Open-water sections were then constructed inside the wetlands, which resulted in enhanced DO concentrations as well as improved treatment efficiency of nutrients and biochemical oxygen demand (BOD). Overall, performance of the constructed wetland was improved BOD, total nitrogen, and total phosphorus with the establishment of open water sections in the constructed wetland system.
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Jethwa, Dr Kruti B. "A Review on Design Basis for Constructed Wetlands for Wastewater Treatment." International Journal for Research in Applied Science and Engineering Technology 9, no. VIII (August 15, 2021): 373–77. http://dx.doi.org/10.22214/ijraset.2021.37163.
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Since last few years Constructed Wetlands (CWs) are being used to treat secondary or tertiary municipal or domestic wastewater effluents have been recognized as an effective means of “green technology” for wastewater treatment. Constructed wetlands (CWs) provide a natural way for simple, inexpensive, and robust wastewater treatment. The idea of natural management systems is the restoration of disturbed ecosystems and their sustainability for remuneration to nature. The Constructed wetlands (CWs) are designed to copy natural wetland systems, utilizing wetland plants, soil and associated microorganisms using various biological, physicochemical processes to remove unwanted constituents from wastewater effluents. This review paper studies various types of constructed wetlands, i.e., surface or subsurface, vertical or horizontal flow and their type of operation, i.e., continuous, batch or intermittent flow, loading rate, selection of plants and wastewater characteristics that affect the treatment efficiency. The design models with their suitability for various parameters and operational conditions such as Darcy’s equation, Kadlec and Knight Model (K-C* model), Arrhenius equation, and population equivalent calculation have been discussed. Lastly, future research requirements have been considered.
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Liu, Yuyang, Bo Feng, and Yu Yao. "Research Trends and Future Prospects of Constructed Wetland Treatment Technology in China." Water 16, no. 5 (February 29, 2024): 738. http://dx.doi.org/10.3390/w16050738.
Full textAbstract:
With the intensification of water pollution problems worldwide, constructed wetlands, as a green, efficient, and energy-saving wastewater treatment technology, have gradually attracted the wide attention of scholars at home and abroad. In order to better understand and master the research trends of constructed wetland treatment technology in China and promote its development, the literature from 2000 to 2023 in the CNKI database and the Web of Science (WoS) database (located in China) were selected as research objects. Then, CiteSpace software (6.2.R4) was used to visualize and analyze the literature, revealing the research trends and hot areas of constructed wetland treatment technology in China. Then, the optimized way of operation effect of constructed wetland was discussed to provide a theoretical and technical basis for the wide application of constructed wetland technology in our country. The results indicate that the annual publication volume of research on constructed wetlands in China is showing a rapid upward trend. Among them, the Chinese literature mainly focuses on how to improve the application effect of constructed wetlands on nitrogen and phosphorus removal of rural domestic wastewater by matching different wetland plants or developing combined processes. The English literature from the Web of Science (WoS) database mainly focuses on how to remove emerging pollutants, such as heavy metals and resistance genes in wastewater in China, by changing the filling matrix and microbial community structure or developing new processes, and the related mechanisms have been discussed. One of the hot spots for the future research of constructed wetlands in China is to vigorously develop microbial fuel cells, and try to overcome the problem of poor purification efficiency of constructed wetlands under complex conditions such as low temperature, low carbon-nitrogen ratio, and high pollution load. In order to strengthen its application, the specific optimization methods can be divided into two categories: self-optimization strategies such as increasing oxygen supply and transfer, providing electron donor matrix, preventing matrix blockage, and combination processes coupled with anaerobic treatment and other technologies.