Dissertations / Theses on the topic 'Natural and constructed wetlands'
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Marron, Corin. "Photodegradation of metolachlor in natural and constructed wetlands." Connect to resource, 2008. http://hdl.handle.net/1811/32058.
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Thomas, Jes. "Comparison of Nitrogen Retention in Wetlands With Different Depths." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-35907.
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The depth of constructed wetlands (CWs) significantly affects the construction investment that influences the efficiency of the CW and is an important design consideration for optimal performance. The aim of the study was to examine the influence of depth on nitrogen retention in 12 pilot scale free surface water CWs in Plönninge (56◦43 45 N, 12◦43 33 E): 6 shallow wetlands with a maximum depth of 0.5 m and 6 deeper wetlands with a maximum depth of 0.8 m. The outlet N concentration in shallow and deep wetlands were found to be significantly different (p<0.05, p= 0.017). Outlet N concentration over the months June to December in deep and shallow wetlands, was found to be significantly different (F (6,60 = 20.594, p< 0.05). and the N concentration in deep and shallow wetlands was significantly different (F (1,10) = 8.087, p<0.05). The N concentration in September was found to be significantly different from those in all other months. The first order rate constant k was calculated for shallow and deep wetlands; higher k value indicates higher nitrogen retention. The deeper wetlands had higher k values than shallow wetlands and was statistically different (p<0.05, p= 0.002) from the k values for shallow wetlands. This implies that the N retention was higher in deeper wetlands than in shallow and was the highest in September. This was most likely due to the effect of temperature and vegetation in the wetlands.
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Johannesson, Karin. "Analysis of phosphorus retention variations in constructed wetlands receiving variable loads from arable land." Licentiate thesis, Linköping University, Linköping, Sweden, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-20140.
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Nowak, Katarzyna. "Carbon storage in free water surface constructed wetlands in southern Sweden." Thesis, Högskolan i Halmstad, Akademin för företagande, innovation och hållbarhet, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-45070.
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Background: Wetlands store significant amounts of carbon through plant respiration and anaerobic peat formation, however, there is little knowledge on which factors affect the carbon storage distribution within wetlands. Aims: To determine how much carbon and nitrogen wetlands can store over time and whether there are patterns of high and low carbon and nitrogen storage within wetlands. Methods: Peat samples of a defined volume, cut out from three constructed wetlands were dried, weighed and analysed for their carbon and nitrogen content. To determine whether there are any patterns in carbon and nitrogen storage distribution or differences between sampling points, their values as well as their ratios were statistically analysed using ANOVA and Kruskal-Wallis. Results: On average 48.94 t C ha-1is stored at the constructed wetland facility which equates 3.06 t C ha-1 storage per year. There is no patterns in carbon storage within wetlands, however, the C:N mass ratio is lower at the inlet suggesting that high N concentrations in inflowing water increases N content. Conclusions: The carbon storage found is significantly lower than storage at natural inland and coastal wetlands, however, similar to anthropogenically affected wetlands. Standardisation across studies through using same sampling depths, vegetation cover measurement and climate classification may help to uncover patterns in carbon storage in the future. Focus should be placed on protecting wetlands rather than restoring them as the latter often fails to restore full functionality. This is especially important for cold climate wetlands which store significantly more carbon through slower plant respiration and subsequently slower re-uptake of carbon.
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Nilsson, Josefin. "Ecosystem age affects nitrate removal in created wetlands." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-37233.
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This study investigates the effect of ecosystem age on the nitrate removal efficiency, nitrate removal rate and first-order area-based removal rate coefficients (both with and without temperature adjustment) of created wetlands. Data was collected from the first to eleventh year after wetland creation in an experimental wetland facility in south-west Sweden. The 18 small (22-29 m2) free water surface wetlands were divided into three groups based on initial planting: EVW (emergent vegetation wetlands), SVW (submerged vegetation wetlands) and CW (unplanted control wetlands). Summer and winter values from the 11 studied years were analysed separately in the repeated measures ANOVA. Over these 11 years the mean nitrate removal efficiency was 12 % and the mean nitrate removal rate was 0.17 g m-2 d-1. Mean removal rate coefficient (K) was 0.020 g d-1 and mean temperature adjusted removal rate coefficient (Ka) was 0.042 g d-1. The best performing wetlands were those initially planted with, and after four years almost completely covered by, emergent vegetation (EVW). This study indicates a positive correlation between wetland age and nitrate removal potential. It further indicates aging may be hastened by initial planting of wetland vegetation.
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Pellnor, Johanna. "Population dynamics of the horned grebe in constructed wetlands in Östergötland." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-176509.
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The population size of the horned grebe, Podiceps auritus, is declining in most of the world due to loss of wetlands, deteriorating water quality and establishment of predatory fish such as pike, Esox lucius, in former fish free wetlands. The horned grebe is now globally classified as vulnerable. In this study, data on population dynamics of the horned grebe in six created wetlands in Linköpings kommun was examined together with field work carried out in three of the wetlands. The results indicate that the number of pairs and juveniles of horned grebe crash six to eight years after the wetland is created and does not recover if there is fish present. The pairs and juveniles of horned grebe decreased significantly with the increasing age of the wetland if there was pike present in the wetland. Reduction fishing and drainage of the water in two of the wetlands inhabited pike showed a small improvement in population size of the horned grebe, but the numbers ultimately declined after a few years. Reduction fishing of common roach in one wetland showed a continuing improvement in the population size of horned grebe. Other factors that affected the horned grebe negatively, was an abundance of macrophytes such as Canadian pondweed, Elodea canadensis, that makes foraging harder.
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Kjellin, Johan. "Coupled Hydrological and Microbiological Processes Controlling Denitrification in Constructed Wetlands." Licentiate thesis, Stockholm : [Mark- och vattenteknik, Kungliga Tekniska högskolan], 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4370.
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Fang, Min. "Removal of Natural and Synthetic Steroid Hormones through Constructed Wetland Microcosm." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1292943388.
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Rosatti, Alessandro. "Costructed Wetlands. A biological alternative wastewater treatments and its role in the new circular economy." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21481/.
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The climate changes, the natural resources depletion, the population number increase are alarm bells for the future that must push the humanity to turn on more sustainable use of the natural resources, particularly the water. The water management must shift towards solutions acted to protect, safeguard, and sustainably use the available water resources. A new water scheme must be implemented, in which the waste paradigm must be overtaken and substituted with resource-oriented one.
The Thesis aims to present the Constructed Wetland (CW) technology, an attractive green solution for wastewater treatment that nowadays is consolidated as a efficient and valid Natural Based alternative to the conventional systems. The different typologies of CWs are exposed as well as their advantages, disadvantages, and applications. The removal pollutant processes (biological, physical, and chemical processes) occurred within, are deeply analysed and the choice of the suitable vegetation species depending on the wastewater characteristic discussed. Furthermore, I give a brief overview on the European and Italian regulations before explaining in details the design (preliminary and empirical) methods. The treatment goodness and effectiveness are discussed and commented with helping of working applications. Finally, the future role of the CWs systems in circular economy approach is clarified and an overview on the water management scheme modification (from waste paradigm to resource-oriented concept) is provided. The potential applications of CWs within this new scheme are outlined and an in-depth study on recreative applications of CW (Natural Swimming Pools technology) are presented.
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Flanagan, Neal E. "Comparing ecosystem structure and function of constructed and naturally occuring wetlands: empirical field indicators and theoreticl indices." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1242846242.
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Flanagan, Neal E. "Comparing ecosystem structure and function of constructed and naturally occurring wetlands : empirical field indicators and theoretical indices /." Connect to resource, 1997. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1242846242.
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Johnson, Brenda Marie. "Remediation of risks in natural gas storage produced waters the potential use of constructed wetland treatment systems /." Connect to this title online, 2006. http://etd.lib.clemson.edu/documents/1171041556/.
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SARTORI, LAURA. "Effects of habitat management and restoration on freshwater ecosystem polulation dynamics." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2013. http://hdl.handle.net/10281/42353.
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Although water quality improvement is generally the primary objective of treatment wetlands, the creation of habitats is an inevitable outcome of these projects. Macroinvertebrate are often early colonists of new created wetlands, with abundance and diversity approaching high levels within a few years from wetland construction. A deeper knowledge of the biodiversity hosted in these environments is needed to evaluate if newly created ponds are appropriate management tools for biological conservation.
The effectiveness of the interventions provided by Parco Pineta di Appiano Gentile e Tradate (a regional park in Lombardy, Italy) in freshwater ecosystem management and restoration has been evaluated, considering a set of natural, artificial and constructed wetlands spread within the park territory.
Considering the macroinvertebrate community and analyzing the biodiversity hosted in all the considered wetlands, no significant differences were found between artificial and natural ecosystems. Even the constructed wetlands, which were characterized by low water quality and higher pollutants concentrations, presented a biodiversity level which in some cases exceeded that one present in natural ecosystems. Even though biodiversity was similar between wetland typologies, differences in community compositions have been enlightened.
The macroinvertebrate community assemblages seemed to be influenced more by the geographical and hydromorphological variables of the ecosystem rather than the physicochemical water characteristics. In particular, water body area and habitat heterogeneity resulted to be the most important variables that influenced the community composition. Seasonal variations in hydrological conditions and resource availability were the main factors that influenced the macroinvertebrate dispersal, evaluated considering life-strategy groups. Although the considered ponds and wetlands presented different features, they all contributed to the local ecological network even if they were not all equally interconnected together.
All the collected information could be useful to design further possible interventions for conservation aims.
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Eke, Paul Emeka. "Hydrocarbon removal with constructed wetlands." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/3155.
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Wetlands have long played a significant role as natural purification systems, and have been effectively used to treat domestic, agricultural and industrial wastewater. However, very little is known about the biochemical processes involved, and the use of constructed treatment wetlands in the removal of petroleum aromatic hydrocarbons from produced and/or processed water. Wastewaters from the oil industry contain aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene (ortho, meta and para isomers), which are highly soluble, neurotoxic and cause cancer. The components of the hydrocarbon and the processes of its transformation, metabolism and degradation are complex, the mechanisms of treatment within constructed wetlands are not yet entirely known. This has limited the effective application of this sustainable technology in the oil and gas industries. Sound knowledge of hydrocarbon treatment processes in the various constructed wetlands is needed to make guided judgments about the probable effects of a given suite of impacts. Moreover, most of the traditional treatment technologies used by the oil industry such as hydrocyclones, coalescence, flotation, centrifuges and various separators are not efficient concerning the removal of dissolved organic components including aromatics in the dissolved water phase. Twelve experimental wetlands have been designed and constructed at The King’s Buildings campus (The University of Edinburgh, Scotland) using different compositions. Selected wetlands were planted with Phragmites australis (Cav.) Trin. ex Steud (common reeds). The wetlands were operated in batch-flow mode to avoid pumping costs. Six wetlands were located indoors, and six corresponding wetlands were placed outdoors to allow for a direct comparison of controlled and uncontrolled environmental conditions. The experimental wetlands were designed to optimize the chemical, physical and microbiological processes naturally occurring within wetlands. The outdoor rig simulates natural weather conditions while the indoor rig operates under controlled environmental conditions such as regulated temperature, humidity and light. Benzene was used as an example of a low molecular weight petroleum hydrocarbon within the inflow of selected wetlands. This chemical is part of the aromatic hydrocarbon group known as BTEX (acronym for benzene, toluene, ethylbenzene and xylene), and was used as a pollutant together with tap water spiked also with essential nutrients. The study period was from spring 2005 to autumn 2007. The research focused on the advancing of the understanding of biochemical processes and the application of constructed wetlands for hydrocarbon removal. The study investigated the seasonal internal interactions of benzene with other individual water quality variables in the constructed wetlands. Variables and boundary conditions (e.g. temperature, macrophytes and aggregates) impacting on the design, operation and treatment performance; and the efficiency of different wetland set-ups in removing benzene, chemical oxygen demand (COD), five-day @ 20°C N-Allylthiourea biochemical oxygen demand (BOD5) and major nutrients were monitored. Findings indicate that the constructed wetlands successfully remove benzene (inflow concentration of 1 g/l) and other water quality variables from simulated hydrocarbon contaminated wastewater streams with better indoor (controlled environment) than outdoor treatment performances. The benzene removal efficiency was high (97-100%) during the first year of operation and without visible seasonal variations. Seasonal variability in benzene removal was apparent after spring 2006, the highest and lowest benzene removal efficiencies occurred in spring and winter, respectively. In 2006, for example, benzene removal in spring was 44.4% higher than in winter. However, no seasonal variability was detected in the effluent ammonia-nitrogen (NH4-N), nitratenitrogen (NO3-N) and ortho-phosphorus-phosphate (PO4 3--P) concentrations. Their outflow concentrations increased or decreased with corresponding changes of the influent nutrient supply. In addition, benzene treatment led to trends of decreasing effluent pH and redox potential (redox) values but increasing effluent dissolved oxygen (DO) concentrations. Approximately 8 g (added to the influent every second week) of the well balanced slow-releasing N-P-K Miracle-Gro fertilizer was sufficient to treat 1000 mg/l benzene. Results based on linear regression indicated that the seasonal benzene removal efficiency was negatively correlated and closely linked to the seasonal effluent DO and NO3-N concentrations, while positively correlated and closely linked to the seasonal effluent pH and redox values. Temperature, effluent NH4-N and PO4 3--P concentrations were weakly linked to seasonal benzene removal efficiencies. During the entire running period, the seasonal benzene removal efficiency reached up to 90%, while the effluent DO, NO3-N, pH and redox values ranged between 0.8 and 2.3 mg/l, 0.56 and 3.68 mg/l, 7.03 and 7.17, and 178.2 and 268.93 mV, respectively. Novel techniques and tools such as Artificial Neural Network (self-organizing map (SOM)), Multivariable regression and hierarchical cluster analysis were applied to predict benzene, COD and BOD, and to demonstrate an alternative method of analyzing water quality performance indicators. The results suggest that cost-effective and easily to measure online variables such as DO, EC, redox, T and pH efficiently predicted effluent benzene concentrations by applying artificial neural network and multivariable regression model. The performances of these models are encouraging and support their potential for future use as promising tools for real time optimization, monitoring and prediction of benzene removal in constructed wetlands. These also improved understanding of the physical and biochemical processes within vertical-flow constructed wetlands, particularly of the role of the different constituents of the constructed wetlands in removal of hydrocarbon. These techniques also helped to provide answers to original research questions such as: What does the job? Physical design, filter media, macrophytes or micro-organisms? The overall outcome of this research is a significant contribution to the development of constructed wetland technology for petroleum industry and other related industrial application.
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Mendonça, Alexandre Antonio Jacob de. "Avaliação de um sistema descentralizado de tratamento de esgotos domésticos em escala real composto por tanque séptico e wetland construída híbrida." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/6/6134/tde-25052016-122129/.
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A concentração demográfica e de sistemas coletivos de esgotamento sanitário dentro do perímetro urbano da maioria dos municípios brasileiros, dificulta a viabilização do fornecimento de serviços de tratamento de esgotos domésticos à habitações e núcleos habitacionais isolados situados em áreas periurbanas e rurais, intensificando os danos provocados pela poluição de origem antrópica ao meio ambiente e à preservação da saúde pública. Para contribuir no equacionamento deste problema, o presente estudo teve por finalidade avaliar uma wetland construída híbrida em escala real, composta por uma unidade com fluxo contínuo subsuperficial vertical seguida por uma unidade de fluxo contínuo subsuperficial horizontal, cultivadas com capim Vetiver, para o tratamento de efluente proveniente de tanque séptico. A presente configuração experimental busca uma solução de baixo custo e simplificada para o tratamento descentralizado de esgotos domésticos. A estação experimental de tratamento de esgotos, parte integrante e um dos produtos da Rede Nacional de Tratamento de Esgotos Descentralizados RENTED, foi construída no Centro Tecnológico de Hidráulica CTH / Escola Politécnica EPUSP, campus Butantã da USP, em São Paulo. O esgoto bruto foi proveniente do Conjunto Residencial da USP e do restaurante central da Cidade Universitária. As vazões média e máxima de esgoto bruto, respectivamente, de 640L.d-1 e 1600L.d-1, foram aplicadas à entrada do TS de 5.000L e deste escoaram por gravidade à entrada da wetland construída híbrida, com TDH total de 2,8d e 1,1d, respectivamente, sob aplicação das vazões média e máxima de projeto. O monitoramento do experimento em campo, incluindo o período inicial de partida, durou 6 meses consecutivos. Foram avaliados os parâmetros físico-químicos e microbiológicos do esgoto bruto e do efluente do tanque séptico e das câmaras da wetland construída híbrida durante 97 dias consecutivos. Os resultados indicaram que tanto as mudas jovens quanto as adultas de capim Vetiver adaptaram-se bem às condições ambientais. As eficiências médias de remoção no efluente tratado final quanto à matéria orgânica carbonácea foram de 96 por cento para DBO5,20 e 90 por cento para DQO, 40 por cento para N-total, 23 por cento para N-amoniacal total, 60 por cento para P-total, 52 por cento para P-PO4, 74 por cento para SST, 96 por cento para SSV, 75 por cento para sólidos sedimentáveis, 44 por cento para SDV, 88 por cento para sulfeto total, e 97 por cento para óleos e graxas totais, variando entre 73 por cento a 100 por cento . Cerca de 80 por cento da fração orgânica da matéria nitrogenada presente no esgoto bruto foi removida. A remoção de coliformes termotolerantes foi, em média, de 2 e 3 unidades log, e de Escherichia Coli, média de 1 e 3 unidades log, respectivamente, sob aplicação das vazões máxima e média, Giardia sp, média de 99,995 por cento , Cryptosporidium sp, média de 98,7 por cento , Enterovírus, média de 99,6 por cento , e Ascaris sp, média de 0,10 ovo/L. A remoção de sulfetos propiciou a geração de efluente tratado sem odores desagradáveis. A diminuição da vazão aplicada e a elevação do TDH influenciaram positivamente no desempenho do sistema com relação às remoções dos parâmetros físico-químicos e microbiológicos. Com base no presente estudo, ficou evidente o benefício da associação de wetlands construídas com fluxo vertical e horizontal no tratamento de efluente de tanque séptico. O capim Vetiver apresentou bom potencial de utilização em wetlands 8 construídas para tratamento de esgotos domésticos. O sistema experimental de tratamento apresentou flexibilidade operacional, mantendo bom desempenho inclusive nos períodos de sobrecarga. A qualidade do efluente tratado final obtido no presente estudo atende às exigências de lançamento e aos padrões de emissão de efluentes líquidos em corpos dágua e em sistemas públicos de esgotamento sanitário definidos na legislação ambiental federal e do Estado de São Paulo. A tecnologia de wetlands construídas híbridas associada ao tratamento de efluentes de tanque séptico apresentou bom potencial para o tratamento descentralizado de esgotos domésticos, inclusive em regiões com pouca disponibilidade de área livre.The demographic concentration and collective systems of sanitation inside the urban perimeter of most Brazilian municipalities, hampers the feasibility of providing sewage treatment services to domestic dwellings and housing isolated nuclei located in peri-urban and rural areas, intensifying the damage caused by pollution of human origin to the environment and to the preservation of public health. For help in solving this problem, the present study had the purpose to evaluate a hybrid constructed wetland full-scale, composed of a unit with continuous vertical subsurface flow followed by a continuous horizontal subsurface flow unit, grown with Vetiver grass, for the treatment of effluent from septic tank. This experimental search setting a low-cost and simplified solution for decentralized treatment of household sewage. The experimental sewage treatment station, integral and one of the products of the Rede Nacional de Tratamento de Esgotos Descentralizados RENTED, was built on the Centro Tecnológico de Hidráulica CTH / Escola Politécnica EPUSP, campus Butantã of USP, in São Paulo. The raw sewage was coming from the residential condominium of the USP and the central restaurant of the University City. The average and maximum flows of raw sewage, respectively, of 640L.d-1 and 1600L.d-1, have been applied to the septic tank input to 5,000L and drained by gravity from the edge of the hybrid constructed wetland with TDH total of 2.8d and 1.1d, respectively, under application of the average and maximum flow rates. Monitoring the experiment in the field, including the early period, lasted 6 months. They were evaluated the physico-chemical and microbiological parameters of raw sewage and effluent from septic tank and the chambers of hybrid constructed wetland during 97 consecutive days. The results indicated that both the young seedlings as the adults of Vetiver grass have adapted well to environmental conditions. The average removal efficiencies in the final treated effluent as to carbonaceous organic matter were 96 per cent for BOD5,20 and 90 per cent for COD, 40 per cent for Ntotal, 23 per cent for N-ammoniacal, 60 per cent for P-total, 52 per cent for P-PO4, 74 per cent for SST, 96 per cent for SSV, 75 per cent for settleable solids, 44 per cent for SDV, 88 per cent for total sulfide, and 97 per cent for oils and greases totals, ranging from 73 per cent to 100 per cent . About 80 per cent of the organic fraction of nitrogen matter present in the raw sewage has been removed. The thermotolerants coliforms removal was, in average, of 2 and 3 log units, and Escherichia Coli, average of 1 and 3 log units, respectively, under application of the maximum and average flow rates, Giardia sp, average of 99.995 per cent , Cryptosporidium sp, average of 98.7 per cent , Enterovirus, average of 99.6 per cent , and Ascaris sp, average of 0.10 eggs/L. Removal of sulfides allowed the generation of treated effluent without unpleasant odors. The decrease in flow rate applied and the elevation of TDH influenced positively on system performance with respect to removals of chemical-physical and microbiological parameters. Based on this study, it became apparent the association benefit constructed wetlands with vertical and horizontal flow in the treatment of wastewater of septic tank. The Vetiver grass has good potential for use in constructed wetlands for wastewater treatment. The experimental system of treatment presented operational flexibility while maintaining good performance even in periods of overload. The quality of the final treated effluent obtained in this study 10 meets the requirements and emission standards of liquid effluents in water bodies and in public sanitation systems defined in federal environmental legislation and the State of São Paulo in Brazil. Hybrid constructed wetlands technology associated with the septic tank effluent treatment showed good potential for decentralized domestic wastewater treatment, including in regions with low availability of free area.
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Balderas-Guzmán, Celina. "Strategies for systemic urban constructed wetlands." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/80907.
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Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2013.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 121-128).
As a result of ubiquitous impermeable surfaces, conventional water management and stormwater infrastructure, and the resultant degradation of natural hydrologic networks, most American urban areas have suffered severely compromised hydrological function and health, particularly related to stormwater and its storage, treatment, and flow. Negative externalities exist at multiple scales: increased disaster vulnerability, climate change, poor water quality, habitat loss, etc. Because upgrading conventional single-purpose infrastructure has become an increasingly cost-prohibitive option, urban areas are finding that reincorporating natural systems can be more effective. In the last 20 years, constructed wetlands have arisen as a promising multi-purpose solution to stormwater problems. Constructed wetlands are artificial systems designed to mimic natural wetlands by using the same physical, biological, and chemical processes to treat water. They are relatively large, but their size gives them high ecological potential and numerous other benefits, such as flooding protection and recreational spaces, while having low life-cycle costs. Since the effectiveness of constructed wetlands comes from mimicking natural wetlands, then the analogy to nature should be extended as far as possible. In nature, wetlands are a system connected to a regional hydrologic network. Therefore, constructed wetlands distributed systemically throughout a watershed have potential to deliver more networked benefits than the current practice of dispersed and disconnected wetlands for individual sites. Yet little research exists examining the implications of urban constructed wetlands in design and planning terms, at multiple scales. In fact, few urban constructed wetland projects for stormwater exist in the first place. This thesis proposes a framework for understanding the potential of systemic constructed wetlands as landscape infrastructure in urban areas. Based on an understanding of science, engineering, and urbanism, this thesis identifies the urban zones of greatest potential for stormwater constructed wetlands and suggests the benefits that could arise out of an urban constructed wetland system, beyond simply water treatment.
by Celina Balderas-Guzmán.
S.M.
M.C.P.
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Freer, Adam. "Pollutant swapping in constructed agricultural wetlands." Thesis, Lancaster University, 2016. http://eprints.lancs.ac.uk/81434/.
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Diffuse agricultural pollution presents a major challenge to global water quality management, requiring the adoption of new land management practices such as constructed agricultural wetlands. These wetlands, promoted in agri-environment schemes, may effectively intercept rainfall-mobilised phosphorus (P), nitrogen (N) and carbon (C). However, wetlands may potentially facilitate ‘pollutant swapping’: the transfer of one form or pathway of pollution for another, as a result of mitigation efforts. Retained pollutants may be remobilised through solubilisation or as the greenhouse gases (GHGs): methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O). Therefore this research examines the potential for agricultural wetlands to ‘swap’ local improvements in water quality, for (1) increased pollution to groundwaters and (2) to the atmosphere. GHG exchanges from an agricultural wetland (area 0.032 ha) in Cumbria, UK were monitored over an 18 month period, using floating gas chambers, ebullition traps and diffusive gas exchange models. While the wetland was a net sink of particulate C and N, mean net releases of CO2 (2249 – 5724 mg m-2 d -1 ), N2O (0.93 – 2.04 mg m-2 d -1 ) and CH4 (169 - 456 mg m -2 d -1 ) were significantly greater than those from adjacent riparian land. Wetland releases of CH4 were most significant in terms of potential atmospheric impact compared to other wetland GHG releases. Shallow groundwater samples extracted from a piezometer network surrounding the study site, illustrated that retained sediments acted as a source of NH4-N and DOC to surface and local groundwaters but mitigated leaching and outward transport of NO3-N to surface and groundwaters. Field and laboratory microcosm experiments demonstrated that pollutant swapping of GHGs and nutrients may be increased during periods of reduced water oxygen content associated with eutrophic conditions. In wetland designs with water depths >0.5 m, anoxic conditions may perpetuate in lower water column zones and facilitate increased CH4 and NH4-N production and storage. Additionally, microcosm studies identified that disturbance of bottom sediments by stormflow may elicit heightened GHG and nutrient releases. Therefore the net impact of wetland construction in catchments may need reconsiderations, with respect to the potentially detrimental effects on water and the atmosphere. However upscaling of observations suggests that wetland implementation in the UK is unlikely to significantly increase GHG budgets. Use of shallower wetlands with vegetation or inlet baffles may reduce CH4 emissions by encouraging oxidation and protecting sediments from storm flows.
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Gorr, Matthew W. "Arsenic Remediation Using Constructed Treatment Wetlands." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1301943769.
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Maharjan, Renu. "Phytoremediation of Selected Pharmaceuticals by and their Phytotoxicity to Aquatic Plants." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1396172003.
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Corbee, Gabriella. "Phosphorus accumulation in constructed wetlands : A study of 10 wetlands constructed on agricultural clay soils in Södermanland." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448096.
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Eutrophication is a major problem causing algal blooms and impaired water quality, especially regarding coastal areas and seas. It is a result of an excessive supply of nutrients such as phosphorus (P), where agriculture accounts for the largest share of the anthropogenic nutrient load. Furthermore, arable fields with clay soils have been shown to have among the highest P-losses. In this study, 10 constructed wetlands located in agricultural areas with high clay content in the topsoil were examined. The aims were to investigate how the P accumulation is related to wetland design and catchment factors and to see if there is an optimal hydraulic load (HL) and wetland size for P accumulation. The study is based on P analyses of sediment cores sampled in March 2021, calculations of catchment factors in ArcMap, water flow calculations, and statistical analyses. Sedimentation of particles with associated P is considered to be the primary process for P retention in wetlands. Accordingly, the results showed that the P accumulation was positively correlated to particle retention. The total P accumulation varied between 8 and 96 kg ha-1 yr-1 and the total particle accumulation was 7-130 t ha-1 yr-1. The wetland design factors, including wetland area, water depth, and length-to-width ratio (L:W), had no significant influence on the P accumulation. However, water depths greater than 1.5 m inhibited the P retention which suggested that the water depth should be limited to approximately 1 m to avoid too large particle settling distances. The proportion of agricultural land within each catchment did not show any correlation to the P accumulation. The clay content in the topsoil was however positively correlated to both particle and P accumulation. This suggested that the sedimentation process was promoted even though the inflowing particles potentially consisted of a large proportion of clay particles, which have a low sedimentation velocity. The erosion risk of the catchment area had no significant influence on the P accumulation, meaning that a high expected particle load did not entail an increased particle and associated P accumulation. High HL values of 450 and 850 m yr-1 were shown to counteract the P retention. This corresponded to wetlands smaller than 0.1% of the catchment area. A possible turning point of HL where the P accumulation is inhibited could also be distinguished, ranging between HL 200 and 300 m yr-1. An optimal HL for increased P accumulation could not be determined due to such few observations. However, it could be concluded that an HL up to approximately 210 m yr-1 had a positive influence on the particle and P accumulation and that wetlands should be larger than 0.1% of the catchment area to efficiently retain P.Övergödning är ett stort problem som orsakar algblomningar och försämrad vattenkvalitet, särskilt vid kustområden och hav. Övergödningen orsakas av ett för stort utsläpp av näringsämnen såsom fosfor (P), där jordbruket står för den största antropogena näringsbelastningen. Åkermark med lerjord har dessutom visat sig ha bland den högsta utlakningen av P. I denna studie har 10 våtmarker anlagda i jordbruksområden med hög lerhalt undersökts. Syftet var att undersöka hur P-ackumuleringen är relaterad till våtmarksutformningen och abiotiska faktorer i avrinningsområdet. Projektet syftade även till att undersöka ifall det finns en optimal hydraulisk belastning (HL) för P-ackumulering. Studien baserades på P-analyser av sedimentproppar provtagna i mars 2021, beräkningar av avrinningsområdesfaktorer i ArcMap, flödesberäkningar samt statistiska analyser. Den primära reningsprocessen för P i våtmarker är genom sedimentation av partiklar med bundet P. Följaktligen visade resultatet att P-ackumuleringen var positivt korrelerad med partikelretentionen. Den totala P-ackumuleringen varierade mellan 8 och 96 kg ha-1 år-1 och den totala partikelackumuleringen var 7-130 ton ha-1 år-1. Våtmarksutformningen, vilket innefattade våtmarksarea, vattendjup och längd-bredförhållande (L:W), hade ingen signifikant betydelse för P-ackumuleringen. Vattendjup större än 1,5 m hämmade emellertid P-ackumuleringen vilket indikerade att vattendjupet bör begränsas till cirka 1 m för att partiklar ska hinna sedimentera. Andelen jordbruksmark i avrinningsområdet hade ingen korrelation med P-ackumuleringen. Lerhalten i avrinningsområdet var däremot positivt korrelerad till både partikel- och P-ackumuleringen. Detta indikerade att sedimentationen främjats trots att de inflödande partiklarna potentiellt bestod av en stor andel lerpartiklar, vilka har en långsam sedimentationshastighet. Erosionsrisken i avrinningsområdet hade ingen signifikant påverkan på P-ackumuleringen. En hög förväntad partikelbelastning resulterade därmed inte en ökad partikel- och P-ackumulering. Höga HL-värden på 450 och 850 m år-1 motverkade P-ackumulationen, vilket motsvarade våtmarker som utgjorde mindre än 0,1 % av avrinningsområdet. En möjlig brytpunkt där HL hämmar P-ackumulationen kunde urskiljas i intervallet HL 200-300 m år-1. På grund av för få observationer kunde inte en optimal HL för ökad P-ackumulation fastställas. Det kunde dock konstateras att en HL upp till cirka 210 m år-1 hade en positiv inverkan på partikel- och P-ackumulationen och att våtmarker bör utgöra minst 0,1 % av avrinningsområdet för att effektivt ansamla P.
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Chiarawatchai, Nathasith. "Implementation of earthworm-assisted constructed wetlands to treat wastewater and possibility of using alternative plants in constructed wetlands." [Hamburg] [TUHH], 2010. http://d-nb.info/100080514X/34.
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Mustafa, Atif. "Nutrient removal with integrated constructed wetlands : microbial ecology and treatment performance evaluation of full-scale integrated constructed wetlands." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4111.
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Wastewaters from intensive agricultural activities contain high concentrations of nitrogen and phosphorus that contributes to water management problems. During the past few years, there has been considerable interest in the use of constructed wetlands for treating surface water runoff from farmyards. If the contaminated runoff is not treated, this wastewater along with other non-point sources of pollution can seriously contaminate the surface water and groundwater. Integrated Constructed Wetlands (ICWs) are a type of free water surface wetlands. They are engineered systems that are designed, constructed and operated successfully for treating farmyard runoff in the British Isles. However, the long-term treatment performance of these systems, the processes involved in contaminant removal and the impact on associated water bodies are not well-known. The aims of this project were to assess the performance of full-scale integrated constructed wetlands and understand nutrient removal in them. Performance evaluation of these systems through physical, chemical and microbiological parameters collected for more than 7 years showed good removal efficiencies compared to international literature. The monitored nutrient concentrations in groundwater and surface waters indicate that ICW systems did not pollute the receiving waters. The role of plants (Typha latifolia) and sediment in removing nutrients was also assessed. More nitrogen and phosphorus were stored in wetland soils and sediments than in plants. The results demonstrate that the soil component of a mature wetland system is an important and sustainable nutrient storage compartment. A novel molecular toolbox was used to characterise and compare microbial diversity responsible for nitrogen removal in sediment and litter components of ICW systems. Diverse populations of nitrogen removing bacteria were detected. The litter component of the wetland systems supported more diverse nitrogen removing bacteria than the sediments. Nitrogen removing bacteria in the wetland systems appeared to be stochastically assembled from the same source community. The self-organising map model was applied as a prediction tool for the performance of ICW and to investigate an alternative method of analysing water quality performance indicators. The model performed very well in predicting nutrients and biochemical oxygen demand with easy to measure and cost-effective water quality parameters. The results indicate that the model was an appropriate approach to monitor wastewater treatment processes and can be used to support management of ICW in real-time.
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Melton, Rebecca Hobbs. "BOD5 removal in subsurface flow constructed wetlands." Texas A&M University, 2003. http://hdl.handle.net/1969.1/2301.
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The frequency of on-site systems for treatment of domestic wastewater is
increasing with new residential development in both rural and low-density suburban
areas. Subsurface flow constructed wetlands (SFCW) have emerged as a viable option
to achieve advanced or secondary treatment of domestic wastewater. The pollutant
removal efficiency in SFCW depends on design parameters. Many of these factors have
been investigated while others such as aspect ratio, design of water inlet structure and
method of dosing the wetland have yet to be fully examined. This study examined the
effect of aspect ratio and header design on BOD5 removal efficiency as well as the
impact of flow rate on flow distribution in a SFCW. An aspect ratio of 4:1 achieved
10% greater removal of organic matter than a 1:1 ratio. Tracer studies demonstrated that
wetlands loaded at a constant rate of 3.8 L/min and 7.6 L/min experienced preferential
flow. In addition, tracer studies showed wetlands with leaching chambers as headers
failed to achieve equal flow distribution. An improvement in effluent water quality was
achieved by replacing the leaching chamber for a perforated manifold as the inlet
structure. This study demonstrated the importance of the careful selection of aspect ratio
and means by which water is introduced to the wetland in the design of SFCW.
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Frazer-Williams, Ronnie. "Constructed wetlands for advanced treatment and reuse." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/2545.
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Constructed wetland technology is gaining increasing attention as a low cost-efficient alternative to high-tech treatment systems for treating municipal and industrial wastewaters especially in small communities. However, its application for grey water reuse has been rarely investigated whilst performance for nutrients (N and P) still remains relatively poor. Pilot scale study was conducted in which three differently configured subsurface constructed wetlands: a horizontal flow reed bed (HFRB), vertical flow reed bed (VFRB) and a novel system - Green Roof Water Recycling System (GROW) were investigated for their suitability and robustness in treating grey water for reuse across a range of influent strengths to represent the limiting conditions observed in the literature. The HFRB and the GROW systems were found to be generally limited to comply with reuse standards especially at high strength. The release of iron from the HFRB media and particulates from the GROW system contributed to the poor turbidity of the final effluent from these systems. Overall, all wetland configurations were able to effectively treat low strength greywater but only the vertical flow system maintained its robustness when high strength greywater was treated. Analysis of the systems reveals this was due to the fact that aerobic metabolism is a more suitable treatment pathway for greywater. Ultimately, the performance of the vertical system was slightly lower but comparable to that of a membrane bioreactor making constructed wetlands a suitable technology for greywater recycling. Also, Bauxol, Red mud, Bayoxide, Ochre, Filtralite-P, Steel slag, concrete, Zeolite and various form of limestones were investigated for potential removal of soluble reactive phosphorous (SRP) and metals (Cu and Ni) in final sewage effluent for post Constructed Wetland System. P capacities exhibited by the different adsorbents correlated with type of metal (e.g. Fe, Al, Ca) and their cation exchange capacities. Ochre exhibited the best P removal ability with a P capacity of 26 g Kg-1 based on a Freundlich isotherm model. The equilibrium sorption capacity of BauxolTM and Ochre based on a Dubinin-Radushkevich model was found to be 4.1 and 4.9 mg g-1 for Cu and Ni unto BauxolTM respectively and 2.6 and 10.2 mg g-1 for Cu and Ni onto Ochre respectively. Kinetic and thermodynamic study revealed a spontaneous and efficient adsorption process via a pseudo-second order mechanism where intraparticle diffusion was shown to be the rate limiting step. An aerobic post constructed wetland system using Ochre as the bed media for large scale applications is suggested.
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Al-Isawi, R. H. "Urban wastewater treatment with mature constructed wetlands." Thesis, University of Salford, 2016. http://usir.salford.ac.uk/41423/.
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Despite the global acceptance for the application of vertical-flow constructed wetlands (VF CWs) as sustainable and cost-efficient technology in treating various types of wastewater, including urban wastewater, continuous loading of wetlands over time can lead to performance inefficiency and generate operational problems especially when high shock loads, such as petroleum hydrocarbon spills, are subjected to the system. Contamination with petroleum hydrocarbon compounds results in changing the structure, function and ecosystem service values of wetlands, which can eventually lead to clogging of the wetland substrate and affect the life time of the system. Sound knowledge of long-term performance in mature vertical-flow constructed wetlands linked with hydrocarbon treatment processes is needed to make guided judgments about the probable effects of a given suite of impacts and revise the management plans accordingly. A study was conducted to compare the impact of different design (aggregate size) and operational (contact time, rest time and chemical oxygen demand (COD) loading) variables on the long-term and seasonal performance of vertical-flow constructed wetland filters operated in tidal flow between June 2011 and March 2016. Ten different vertical-flow wetland systems were planted with Phragmites australis (Cav.) Trin. ex Steud. (Common Reed). Approximately 130 and 975 grams of diesel fuel (equivalent to 20 and 150 grams/litre, respectively) were each poured into four wetland filters on 26/09/2013 and 26/09/2014 respectively. Overall findings showed that the mature wetland system improved the water quality except for ortho-phosphate-phosphorus (PO₄-P), which reduced less over time. Findings also indicated that the wetland filter with the highest chemical oxygen demand (COD) loading but no diesel contamination performed the best in terms of COD and biochemical oxygen demand (BOD) removal. Filters contaminated by diesel performed worse in terms of COD and BOD but considerably better regarding nitrate-nitrogen removal. The removal efficiencies dropped for those filters impacted by the diesel spills. Seasonal analysis for water quality from different wetlands showed clear seasonal outflow concentration trends (low in summer) for COD, and nitrate-nitrogen (NO₃-N) while effluent BOD showed high treatment performance in winter. No clear seasonal trend for ammonia-nitrogen (NH₄-N), PO₄-P or suspended solids (SS) was noted. Serious clogging phenomena, impacting negatively on the treatment performance and the hydraulic conductivity, were not observed. The simulation model confirms the experimental findings that notable wetland clogging restricting the operation did not occur. Moreover, results showed that small aggregate diameter, low inflow COD load, and high contact and rest time were most efficient in reducing SS accumulation within the wetland filter bed. With regard to the treatment performance of the hydrocarbon contaminants, results indicated that all wetland systems had a relatively good performance in treating petroleum hydrocarbon compounds and the evaluation showed that all the hydrocarbon components were highly degraded and their concentrations were reduced in all treated effluents of wetland filters with time. This indicates that VF CW zones provide appropriate conditions for high treatment capacity of diesel compounds spilled with urban wastewater by a combination of processes taking place in the wetland filters, thus minimizing hydrocarbon compounds within the filter. A new experimental artificial ponds system, including: ponds with wastewater; ponds with wastewater and reeds; and ponds with wastewater, reeds and aeration, was operated in parallel with the mature experimental vertical-flow constructed wetland system, for the period between July 2015 and October 2015, to compare performance, design and operation variables between the two treatment technologies in the treatment of urban wastewater. Findings showed that highest COD and SS removals were observed for wetlands in comparison to ponds. Moreover, mature wetlands were better in removing NH₄-N and PO₄-P than ponds unless the ponds were aerated. Both systems were linked with medium to high levels of BOD removal. The aerated pond system demonstrated better treatment performance in terms of NH₄-N and PO₄-P. The NO₃-N concentration increased in the aerated ponds reflecting the high oxygen availability. Due to increasing water scarcity and droughts, which are key concerns worldwide, there is considerable interest in recycling various wastewater streams, such as treated urban wastewater, for irrigation in the agricultural sector. Recycling of effluents from various wetland filters (with/without diesel contamination) was assessed for the irrigation of chilli plants (De Cayenne; Capsicum annuum (Linnaeus) Longum Group ‘De Cayenne’) grown in a greenhouse environment. Concerning chilli fruit numbers, findings showed that the highest fruit yields for all wetland filters were associated with those that received inflow wastewater with a high loading rate, reflecting the high nutrient availability in treated wastewater, which is of obvious importance for yield production. Findings also indicated that wetlands without hydrocarbon contamination, with small aggregate size, low contact time, and low inflow loading rate provided high marketable yields (expressed in economic return). In comparison, chillies irrigated by filters with hydrocarbon contamination, small aggregate size, high contact time and high loading rate also resulted in high marketable yields of chillies, which pointed out the role of high contact time and high inflow load for better diesel degradation rates. The overall outcome of this research could considerably contribute to optimization of the design and development of long-term operation variables for constructed wetland technology particularly in petroleum industry applications. Statistically validated long-term data interpretation can particularly help the wetland modelling community and wetland managers to define, with insight into long-term and seasonal factors, removal processes for individual water quality parameters to maximize wetlands treatment performance.
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Mann, Robert A., of Western Sydney Hawkesbury University, and Faculty of Science and Technology. "Phosphorus removal by constructed wetlands : substratum adsorption." THESIS_FST_XXX_Mann_R.xml, 1996. http://handle.uws.edu.au:8081/1959.7/333.
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The phosphorus removal characteristics of several gravel-based constructed wetland systems (CWSs) in the treatment of secondary sewage effluent was studied.Investigations were conducted on water quality parameters (redox potential, pH, dissolved oxygen and temperature) which affect phosphorus adsorption to substrata.Laboratory phosphorus adsorption experiments on Richmond CWS gravel substrata, a gravel used in Griffith CWS trials and a locally available soil, Hawkesbury sandstone, involved ion-exchange experiments and calculation of Langmuir and Freundlich adsorption isotherms and column adsorption/desorption trials.Six steelworks by-products were investigated in laboratory studies, to determine their potential for use as phosphorus adsorbers in a CWS: granulated blast furnace slag(GBF), blast furnace slag(BF), steel slag(SS), fly ash(FA), bottom ash(BA) and coal wash(CW).The ability to adsorb phosphorus was then correlated to the chemical attributes of each substratum.Of the six steelworks by-products screened in laboratory-based studies as substrata for P removal in a CWS, BF and SS slags showed the most potential due to their high phosphorus adsorption capacity and useable matrix size.Further research is recommended to evaluate the sustainability of using slags for P removal (as well as other contaminants present in wastewater), using full scale CWSs, which should include an evaluation of any likely environmental impacts using leachability and toxicity studies.Doctor of Philosophy (PhD)(Environmental Science)
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Vinluan, Edlin Artuz. "Survival of Microbial Indicators In constructed Wetlands." Thesis, The University of Arizona, 1996. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0275_sip1_w.pdf&type=application/pdf.
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Mann, R. A. "Phosphorus removal by constructed wetlands : substratum adsorption /." View thesis View thesis, 1996. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030514.171450/index.html.
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Sundberg, Carina. "Nitrifyers in constructed wetlands treating landfill leachates." Doctoral thesis, Linköping : Department of Clinical and Experimental Medicine, Linköping University, 2008. http://www.bibl.liu.se/liupubl/disp/disp2008/med1067s.pdf.
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Hussain, Syed. "Removal of poultry pharmaceuticals by constructed wetlands." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104564.
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The main focus of the study was on three ionophoric antibiotics, monensin salinomycin and narasin. These three pharmaceuticals were evaluated both in vivo and in vitro setups to understand their fate and behavior in a constructed wetland (CW) environment. The laboratory studies determined the sorption, degradation and photodegradation potential in context of a wetland setup and, the field-scale CW experiments appraised the pharmaceutical removal potential under three flow configurations: free water surface (FWS), horizontal subsurface flow (HSSF) and vertical flow (VF) systems. FWS and HSSF systems were evaluated with two texturally different soils while the vertical system employed sphagnum peat moss. The laboratory sorption study was conducted on both soils at three pH levels, namely 4.5, 6.8, and 8.5. At pH 6.8, it was found that the sandy clay loam soil had higher Kd values for all three antibiotics as compared to the sandy soil. Narasin showed the highest Kd and Koc, whereas the lowest were observed for monensin. The sorption of all compounds had an inverse relationship with pH. In the biodegradation study on both soils, three concentrations of each compound, 100, 500, and 1000 μg kg-1, were used. First order degradation was observed for all three pharmaceuticals, with half-lives ranging from 6 to 8 days in both soils. The photodegradation study was carried out at three concentrations of each pharmaceutical on sterilized milli-Q water, sterilized milli-Q water with nitrate-N, and sterilized wetland water. Photodegradation was observed only for the wetland water; it also followed first-order decay with a half-life of 55, 40, and 37 days for monensin, salinomycin, and narasin, respectively. The first CW study determined the removal efficiency of two FWS wetland systems, one with sandy clay loam soil and the other with sandy soil, and a VF system with sphagnum peat moss for monensin, salinomycin and narasin. The results showed a significantly higher removal (P< 0.01) of all three antibiotics in FWS system using the sandy soil as compared to the CW on the sandy clay loam soil substrate. The ability to infiltrate to greater depths of the soil profile is likely to provide greater opportunity for soil-to-solute interactions, resulting in higher attenuation mainly through sorption in the sandy soil. However compared to the FWS systems, significantly enhanced removal (P < 0.0001) was observed in VF system using peat. Monensin and narasin were found to be the most and the least mobile in all three systems. The second field study assessed the removal potential of the sandy soil in a field scale horizontal subsurface flow (HSSF) treatment wetland for the three antibiotics. Compared to the FWS treatment, the HSSF treatment significantly (P < 0.001) removed greater monensin (40% vs 32%), salinomycin (49% vs 34%) and narasin (49% vs 38%). Based on temperature, oxidation-reduction potential and dissolved oxygen measurements, significant contribution of microbial degradation could not be confirmed.In another study, N-removing bacterial strains were isolated from an antibiotic exposed wetland. The strains were identified using nucleotide sequence analysis of the 16S rRNA gene; the isolates were assessed for their ability to withstand these pharmaceuticals. A Bacillus subtilis strain BRAZ2B was found to thrive in the drug-exposed wetland environment.Des méthodes à la fois in vivo et in vitro servirent à élucider le devenir et le comportement de trois antibiotiques ionophores (monensin, salinomycine and narasine) dans l'environnement d'un marais artificiel (MA). Des études in vitro en laboratoire établirent le potentiel de sorption et de décomposition de ces composés dans un loam sablo-argileux et un sol sableux, ainsi que celui de photodégradation dans l'eau de marécage. Des études avec MA à l'échelle préindustrielle déterminèrent le potential d'élimination de ces trois produits pharmaceutiques sous trois types d'écoulement: en surface libre (FWS), souterrain horizontal (HSSF) et en circulation verticale (VF). Le système FWS fut évalué avec les deux types de sols, tandis que le système HSSF ne fut évalué que pour le sol sablonneux. Le système de circulation en vertical utilisa de la tourbe mousseuse de sphaignes. In vitro le niveau de sorption des composés présenta une relation inverse au pH pour des valeurs de 4.5, 6.8, and 8.5. À un pH de 6.8, les valeurs de Kd pour tous les composés furent plus élevés pour le loam sablo-argileux que pour le sol sableux. La narasine montra les valeurs les plus élevées de Kd and Koc, tandis que le monensin montra les moins élevées. Trois concentrations (100, 500, et 1000 μg kg-1) de chaque composé, appliqués sur chacun des deux sols, présentèrent tous une cinétique de dégradation de premier ordre, avec des demi-vie d'élimination de 6 à 8 jours. Le potential de photodégradation des trois composés fut évalué dans de l'eau de marécage pré-stérilisé, de l'eau distillé (milli-Q) et de l'eau distillé dopé de nitrates. La photodégradation n'eut lieu que dans l'eau de marécage, où elle suivit une cinétique de dégradation de premier ordre, avec des demi-vies d'élimination de 55, 40, et 37 jours, respectivement, pour le monensin, la salinomycine, and la narasine. Dans une première étude, on évalua l'éfficacité d'élimination de ces composés par les deux systèmes FWS — un avec loam sablo-argileux et un avec sol sableux — et un système VF avec tourbe mousseuse de sphaignes. Le système FWS avec sol sableux comme substrat élimina significativement plus les trois antibiotiques (P< 0.01) que celui avec un loam sablo-argileux. La capacité des composés dissouts de pénétrer le profil sableux permit probablement des conditions plus favorables aux interactions sol-soluté. Ceci aurait ensuite permis une plus ample atténuation, principalement par sorption au sol sablonneux. Le rôle de la biodégradation, particulièrement dans le loam sablo-argileux, fut aussi noté. Cependant, comparé aux systèmes FWS, le système VF avec tourbe permit une élimination significativement plus élevée (P < 0.0001). Dans les trois systèmes, le monensin et la narasine s'avérèrent les composés le plus et le moins mobile, respectivement. Dans une seconde étude on évalua le potentiel d'élimination des trois antibiotiques grâce à un système HSSF pleine échelle avec sol sablonneux. Comparé au système FWS comportant le même substrat, le système HSSF élimina significativement (P < 0.01) plus de monensin (40% vs. 32%), salinomycine (49% vs. 34%) et narasine (49% vs. 38%). Un suivi de la température, du potentiel d'oxydo-réduction et de l'oxygène dissout, ne permirent pas de confirmer une contribution significative de la dégradation microbienne.En une dernière étude, des souches bactériennes compétentes à l'élimination de l'azote furent isolées d'un marécage exposé à des antibiotiques. Ces souches furent identifiées par détermination de la séquence nucléotidique d'ARNr 16s, et leur capacité de résister à ces composés pharmaceutiques fut évaluée. Une souche de Bacillus subtilis (BRAZ2B) s'avéra capable de se développer vigoureusement dans l'environnement du marécage exposé à ces composés.
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Knowles, Paul. "Clogging in horizontal subsurface flow constructed wetlands." Thesis, Aston University, 2012. http://publications.aston.ac.uk/18725/.
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Horizontal Subsurface Flow Treatment Wetlands (HSSF TWs) are used by Severn Trent Water as a low-cost tertiary wastewater treatment for rural locations. Experience has shown that clogging is a major operational problem that reduces HSSF TW lifetime. Clogging is caused by an accumulation of secondary wastewater solids from upstream processes and decomposing leaf litter. Clogging occurs as a sludge layer where wastewater is loaded on the surface of the bed at the inlet. Severn Trent systems receive relatively high hydraulic loading rates, which causes overland flow and reduces the ability to mineralise surface sludge accumulations. A novel apparatus and method, the Aston Permeameter, was created to measure hydraulic conductivity in situ. Accuracy is ±30 %, which was considered adequate given that conductivity in clogged systems varies by several orders of magnitude. The Aston Permeameter was used to perform 20 separate tests on 13 different HSSF TWs in the UK and the US. The minimum conductivity measured was 0.03 m/d at Fenny Compton (compared with 5,000 m/d clean conductivity), which was caused by an accumulation of construction fines in one part of the bed. Most systems displayed a 2 to 3 order of magnitude variation in conductivity in each dimension. Statistically significant transverse variations in conductivity were found in 70% of the systems. Clogging at the inlet and outlet was generally highest where flow enters the influent distribution and exits the effluent collection system, respectively. Surface conductivity was lower in systems with dense vegetation because plant canopies reduce surface evapotranspiration and decelerate sludge mineralisation. An equation was derived to describe how the water table profile is influenced by overland flow, spatial variations in conductivity and clogging. The equation is calibrated using a single parameter, the Clog Factor (CF), which represents the equivalent loss of porosity that would reproduce measured conductivity according to the Kozeny-Carman Equation. The CF varies from 0 for ideal conditions to 1 for completely clogged conditions. Minimum CF was 0.54 for a system that had recently been refurbished, which represents the deviation from ideal conditions due to characteristics of non-ideal media such as particle size distribution and morphology. Maximum CF was 0.90 for a 15 year old system that exhibited sludge accumulation and overland flow across the majority of the bed. A Finite Element Model of a 15 m long HSSF TW was used to indicate how hydraulics and hydrodynamics vary as CF increases. It was found that as CF increases from 0.55 to 0.65 the subsurface wetted area increases, which causes mean hydraulic residence time to increase from 0.16 days to 0.18 days. As CF increases from 0.65 to 0.90, the extent of overland flow increases from 1.8 m to 13.1 m, which reduces hydraulic efficiency from 37 % to 12 % and reduces mean residence time to 0.08 days.
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Taylor, Carrie Renee. "Selecting plant species to optimize wastewater treatment in constructed wetlands." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/taylor/TaylorC0509.pdf.
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Constructed wetlands are used around the world for treating domestic, agricultural, and industrial wastewater, stormwater runoff, and acid mine drainage. Plants may affect efficacy of wastewater treatment through their influence on microbial activity by creating attachment sites and releasing carbon exudates and oxygen. My research investigated seasonal plant effects on wastewater treatment by monitoring water chemistry in model subsurface wetlands planted with monocultures of 19 plant species and unplanted controls. Chemical oxygen demand (COD) removal, an indicator of water quality, declined during colder temperatures in the unplanted control, likely caused by a decrease in microbial activity. In contrast, wetlands with most plant species had constant COD removal across seasons. Redox potential and sulfate concentrations were measured as indirect measurements of the oxygenation of the wastewater. Wetlands that had a decline in COD removal during cold temperatures had constant low redox potential and sulfate concentrations throughout the seasons. Wetlands with high COD removal across seasons had elevated redox potentials and sulfate concentrations during the winter, indicating elevated oxygen availability, which may offset the negative temperature effect on microbial processes. I measured root oxygen loss (ROL) in the summer and the winter to determine whether oxygen release was sufficient to influence wastewater treatment and cause seasonal and species-specific effects on water chemistry. COD removal and ROL were positively correlated at 4°C but not at 24°C; however, the amount of root oxygen release only accounted for a portion of the required oxygen to facilitate plant's influence on COD removal. Flooding tolerance was quantified for each species by comparing plants' biomass between flooded and drained conditions. Plants' botanical grouping, Wetland Indicator Status, and flooding tolerance were compared to plants' influences on wastewater treatment to determine whether easily measured plant traits can be used to identify plants that will optimize wastewater treatment. All the sedges and rushes, obligate wetlands species, and 8 of 9 flood-tolerant plants had greater COD removal than the control at 4°C, the coldest temperature incubation. These results can be applied for wetland design by selecting plant species to optimize wastewater treatment, especially in cold climates.
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Samsó, Campà Roger. "Numerical modelling of constructed wetlands for wastewater treatment." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/144624.
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Constructed Wetlands (CWs) are a wastewater treatment technology that inherits the purification potential of natural wetlands and optimizes it to comply with regulations for treated discharges. CWs have become an equally performing alternative to conventional wastewater treatment technologies of communities up to 2000PE, with lower energy and maintenance costs. Despite their potential, CWs lack reliability, which holds back their full deployment in the territory. This fact results from the lack of understanding on their internal functioning and because they are prone to clogging.
The enormous diversity of CWs typologies and operation strategies, and the fact that they operate at the mercy of the environmental conditions, makes each CW unique on its kind, and experimental studies are usually only representative of the studied system. This fact makes mathematical models essential to study their functioning. Several models for CWs have proliferated in the last dozen years to provide supporting tools for their design and operation as well as more insight into the treatment processes. However, compared to models utilized in similar disciplines, CWs models are still in an embrionary stage.
Accordingly, the objectives of the current work were to develop a CWs model able to describe the most common processes taking place within CWs, and to use this model to shed light on the internal functioning of these systems in the long-term.
The model, named BIO_PORE, was built in COMSOL Multiphysics and can simulate subsurface flow and pollutants transport in porous media. It also implements the biokinetic model Constructed Wetlands Model number 1 (CWM1) to describe the fate of organic matter, nitrogen and sulphur and the growth of the bacterial groups found in CWs. The model was calibrated with experimental data of a year of operation of a pilot system.
Two empirical parameters (Mcap and Mbio_max ) were used to improve the description of bacterial growth obtained with CWM1 and to include the effects of solids accumulation on bacterial communities. The effect of these two parameters was evaluated using local sensitivity analysis. The model was later used to unveil the dynamics of bacterial communities within CWs. In addition, a theory was derived from simulation results, which aimed at describing the most basic functioning patterns of CWs based on the interaction between bacterial communities and accumulated solids. At the end of the document a mathematical formulation is presented to describe bioclogging and a numerical experiment is carried out to showcase its impact on simulation results.
The main outcome of the current work was the BIO_PORE model. This model was able to reproduce effluent pollutant concentrations measured during an entire year of operation of the pilot system. Parameters Mcap and Mbio_max proved essential to prevent unlimited bacterial growth predicted by CWM1 near the inlet sections of CWs. These two parameters were also responsible for the good fitting with experimental data. This was confirmed with the sensitivity analysis, which demonstrated that they have a major impact on the model predictions for effluent COD and ammonia and ammonium nitrogen. The theory derived from simulation results indicated that bacteria move towards the outlet with time, following the accumulation of inert solids from inlet to outlet. This result may prove that CWs life-span is limited, corresponding to the time after which bacterial communities are pushed as much towards the outlet that their total biomass is not able to provide effluents with acceptable quality. The inclusion of bioclogging was a requisite to reproduce the bacterial distribution and fluid flow and pollutants transport within CWs.
More work on the BIO_PORE model is required and more experimental data is necessary to calibrate and validate its results.
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Demin, Oleg Alexandrovich. "Remediation of ammonia rich minewater in constructed wetlands." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268403.
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Lewis, G., and Phillip R. Scheuerman. "Bioremediation Potential of Creosote Constituents Using Constructed Wetlands." Digital Commons @ East Tennessee State University, 1993. https://dc.etsu.edu/etsu-works/2895.
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Lee, Byoung-Hwa. "Constructed wetlands for the treatment of concentrated stormwater runoff : design and operation of experimental constructed wetlands applied for gully pot liquor treatment, and application of machine learning techniques to support constructed wetlands management." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/15197.
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The aim of this research was to assess the treatment efficiencies for concentrated stormwater runoff (gully pot liquor) of experimental vertical-flow constructed wetland filters containing common reed and different aggregates. For two years, six out of twelve filters received inflow water spiked with hydrated nickel and copper nitrate to simulate contaminated primary treated storm runoff. For those six constructed filters, an obvious breakthrough of dissolved nickel was recorded after road salting during the first winter. However, a breakthrough of nickel was not observed since the inflow pH was raised to eight after the first year of operation. During the second year, reduction efficiencies of heavy metals, five-day biochemical oxygen demand (BOD) and suspended solids (SS) improved considerably. Concentrations of BOD were frequently <20 mg/l, an international threshold for secondary wastewater treatment. This is likely due to biomass maturation and the increase of pH. Machine learning techniques such as K-nearest neighbours, support vector machine and self-organizing map were applied to predict BOD and SS, and to demonstrate an alternative method of analyzing water quality performance indicators. The results suggest that BOD and SS can be efficiently estimated by applying machine learning tools with cost-effective input variables such as redox potential and conductivity, which can be monitored in real time. Their performances are encouraging and support the potential for future use of these models as management tools for the day-to-day process control of constructed wetlands and other ‘black box’ systems.
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[Verfasser], Nathasith Chiarawatchai. "Implementation of earthworm-assisted constructed wetlands to treat wastewater and possibility of using alternative plants in constructed wetlands / von Nathasith Chiarawatchai." [Hamburg] : [TUHH], 2010. http://d-nb.info/100080514X/34.
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Faulwetter, Jennifer Lynn. "Analysis of microbial biofilm community composition within constructed wetlands." Diss., Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/faulwetter/FaulwetterJ1210.pdf.
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Constructed wetlands (CWs) are ecologically-based water treatment systems that provide cost-effective amelioration of waterborne pollutants. Fundamental understanding of removal mechanisms, especially microbial processes, limits greater usage of constructed wetlands as a wastewater treatment system. The influence of plant species selection, season, and organic load rate on pollutant removal was previously linked to the redox condition of the sub-surface wetland environment. The goal of this research was to determine which of these environmental variables (including spatial location within the CW) influenced the dominant microbial populations and/or the activity of various sub-populations. Once identified, a constructed wetland might be optimized for growth of microorganisms involved in removal of a specific pollutant. To assess environmental factors, microbial population samples were taken in six locations (effluent, 3 root and 2 gravel areas) within replicate unplanted microcosms and wetland microcosms planted with Deschampsia cespitosa or Leymus cinereus during the summer (24°C) and winter (4°C) seasons. Microcosms were fed a synthetic domestic wastewater in 20-day batches for at least 12 months prior to sampling. The most recent techniques in molecular biology including denaturing gradient gel electrophoresis (DGGE) and quantitative PCR were utilized and included treatment with and without propidium monoazide (PMA) to distinguish between "live" and "dead" microbial communities. Primer sets targeted the entire bacterial community (16S rDNA) and two functional groups, nitrifying bacteria (amoA gene) and sulfate reducing bacteria (dsrB gene). Results indicated that overall microbial community structure (16S rDNA) was affected by general location within the microcosm (effluent, root, gravel) as well the plant species present. Specific microbial groups appeared to be affected differently with relative gene quantities of sulfate reducing bacteria and nitrifying bacteria being influenced by a combined effect of plant species and season. For dsrB, D. cespitosa had the lowest relative gene quantities overall. Both genes were more abundant in the summer season, indicating seasonal importance. Location within the microcosms was also important, with anoxic environments (column bottom) being more important for dsrB presence and a diverse population of cultivated sulfate reducers. The roots were an important location for both microbial diversity and activity for all genes investigated.
'Co-authored by Vincent Gagnon, Carina Sundberg, Florent Chazarenc, Mark D. Burr, Jacques Brisson, Anne K. Camper, Otto R. Stein, Albert E. Parker, Alfred B. Cunningham, and Frank M. Stewart.'
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Rivard, Stephanie. "Evaluation of Continuous Flow Constructed Wetlands Treating Swine Waste." TopSCHOLAR®, 1997. http://digitalcommons.wku.edu/theses/352.
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The ability for wetlands to purify contaminated water is not a new concept. Natural wetlands have been cleansing water within our environment for ages. After studying the process of natural wetlands the same concept was applied to municipal waste. It is the success of constructed wetlands treating municipal waste that created the new idea for the application of a wetland system to treat wastewater from livestock facilities. Through proper design and management, constructed wetlands may be useful for reducing the nutrient concentration of waste (Rieck el al., 1996). Taking into consideration the higher nutrient loads of livestock waste, the same basic idea of constructed wetlands used for municipal waste is being utilized to protect public water sources from contamination of livestock wastes. In this study a constructed wetland (total recycle) built for the purification of swine waste was evaluated. In cooperation with Pig Improvement Company of Allen County, Kentucky, water samples were collected from the nine connected cells making up the wetlands created at The Dogwood Ridge Farm. After collection of the samples, they were analyzed at the Western Kentucky University Environmental Laboratory. Samples were tested for levels of the following parameters: • Ammonia Nitrogen • Nitrate Nitrogen • Total Phosphorus • Biological Oxygen Demand • Total Suspended Solids • Total Dissolved Solids • Fecal Coliform • Conductivity • Mineral Elements The data in this report accounts for seven sample dates throughout 1996. Samples were also collected for three additional months prior to the first sample date in which data is reported, although these dates are considered to be a part of the initial start up phase for the testing period. Sample dates within the start up phase are not included among the results. With greater concern directed towards higher water quality standards, there is the need to eliminate any activities resulting in non-point source pollution (NPS). Livestock waste is considered one of the leading causes of NPS pollution which has created this awareness for better waste management. As traditional waste treatment equipment is commonly too expensive for the average livestock producer, constructed wetlands are proving to be an affordable, environmentally friendly, and manageable solution for livestock waste treatment.
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Brook, Graham R. "The significance of constructed wetlands for practical environmental education /." Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09ENV/09envb871.pdf.
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Thomas, R. "The removal of linear alkylbenzene sulphonate in constructed wetlands." Thesis, Bangor University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273674.
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Tiefenau, Börge Mike. "Is phosphorus limiting the nitrogen removal in constructed wetlands?" Thesis, Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-26257.
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Two mesocosm studies were performed in a laboratory to figure out the relevance of the phosphorus concentration to the nitrogen removal in wetlands. The main intention was to see if phosphorus is limiting the process of denitrification. In both experiments, plastic beakers (n=20) were filled with inlet water and plant litter material from the ground of a constructed wetland near Halmstad, Sweden.. The litter consisted mainly of dead leaves of Phragmites australis and the water, originating from an agricultural site, had a high concentration of total nitrogen (around 9 mg/L), but a low concentration of phosphorus (around 20 µg/L). The experiment was performed in darkness and in the mesocosms prevailed anaerobic conditions. Half of the beakers were filled with phosphorus enriched water and water samples were obtained at several times and analyzed for nitrate, total nitrogen and total phosphorus to determine the nitrogen removal. In addition the plant material was analyzed for nitrogen and carbon content before and after the experiment with a carbon/nitrogen-analyzer. The mean removal rates of nitrogen were higher in the mesocosms which were treated with additional phosphorus. In a long-term perspective from the second experiment, the mean removal rates are declining faster in the non phosphorus treated beakers. The analysis of the plant litter material could not show if nitrogen was removed from systems through denitrification or just taken up and stored by microorganisms. The experiment was carried out under controlled conditions. The results show that the effect of P on denitrification is not completely understood yet and further research especially on the N uptake by microorganisms and long-term experiments are needed.
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Richter, Klaus M. "Constructed wetlands for the treatment of airport de-icer." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401070.
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Griffith, Kevin L. (Kevin Lynn). "Constructed wetlands : a growing opportunity for the construction industry." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/45719.
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Vidales, Contreras Juan Antonio. "Removal of viruses and pollution indicators in constructed wetlands." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/280464.
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Tracer studies using Br⁻ and bacteriophage PRD1 in both surface and subsurface flow constructed wetlands were conducted to analyze their hydrodynamic behavior and efficiencies in removing viruses from wastewater. A survival test in situ was also conducted to analyze the persistency of PRD1 in wetland environments. Concurrently, a sampling program for microbial and chemical indicators in the surface flow wetland for a period of 16 months was conducted. The tracer studies revealed a reduction of 99 and 84 percent in the subsurface and surface flow wetland, respectively. Bromide recovery at the outlet of both wetland systems was about 75 percent. The Convective-Dispersion Equation was able to predict the observed PRD1 and Br⁻ breakthrough curves obtained during the tracer study in the surface flow wetland. The monitoring program of pollution indicators showed that biochemical oxygen demand and total suspended solids can be reduced efficiently, reaching the tertiary effluent standard of 10 mg L⁻¹ required by The Arizona Department of Environmental Quality. This sampling program suggested that coliphages may be a better indicator of fecal contamination than total and fecal coliforms in surface flow wetlands.
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Nan, Xi <1992>. "Constructed wetlands for water management and reuse in agriculture." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/8748/1/Nan_Xi_thesis.pdf.
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Global warming mainly induced by anthropogenic causes has already restricted the increase in agricultural productivity along with aggravating the conflict between water supply and demand. In this context, constructed wetlands (CWs) can be one of nature-based solutions for the treatment and reuse of unconventional wastewater sources. The aim of this research was to evaluate the performance of CWs in wastewater treatment (i.e., agricultural drainage water and domestic wastewater) and to explore the potential of their effluents for agricultural reuse. In order to achieve this goal, the work based on literature review and experimental approach was carried out. The findings showed that CWs can be an effective option for treating both agricultural drainage water (ADW) and domestic wastewater. It was also found that systems treating ADW can be effective even after a long period of operation. The treatment performance of CW systems is affected by the design and operational factors. For instance, the application of simple hydraulic structures and vegetation establishment can improve the pollutant removal efficiencies by increasing hydraulic retention time. Moreover, the addition of other technologies (e.g., UV treatment, anaerobic reactors) could further improve the quality of wastewater treated by single-stage CWs. In particular, it is strongly recommended to add special disinfection technologies to CW treatment systems to meet agricultural reuse standards since it was shown that the microbial loads often exceed the limits (e.g., E. coli).
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Chow, Siu-hang. "Vibrant green spine and constructed wetland in Tuen Mun River." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38317540.
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Thesis (M. L. A.)--University of Hong Kong, 2007.Title proper from title frame. Includes special report study entitled: Constructed wetland for wildlife, drainage and sewage treatment. Also available in printed format.
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Kirkpatrick, Amber Denise. "Assessing constructed wetlands for beneficial use of saline-sodic water." Thesis, Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/kirkpatrick/KirkpatrickA0505.pdf.
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Fernandes, Maria de Fátima Azevedo Alexandrino. "Studies on the processes of bacteria elimination in constructed wetlands." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=981543707.
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Kapira, Elvanus. "EFFECTS OF PLANT HARVESTING ON NUTRIENTS REMOVAL IN CONSTRUCTED WETLANDS." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-35170.
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Insufficient access to clean water and sanitation has become one of the most universal problems affecting human health in developing countries, water resources are facing high pollution rate due to improper management of wastewater. Ecological technologies such as constructed wetlands are promising innovative solutions for this universal problem. Constructed wetlands are engineered wastewater treatment systems that include treatment segments such as physical, chemical, and biological processes like in natural wetlands. Plant harvesting practice is one management strategy that can prevent these systems from clogging and loss of surface area, the effects of this management strategy need to be assessed related to the performance of wetlands. The aim of this thesis was to investigate the effects of plants harvesting on nutrients removal (N, P, and COD) in constructed wetlands. This is a literature review and experimental based thesis. The literature review involved reviewing 5 studies about effect of harvesting plants in constructed wetlands. The experiment part involved data analysis from 6 experimental wetlands, with 3 wetlands that have been harvested in 2015 and 2016, another 3 wetlands that have never been harvested. Results from literature review indicated that plant harvesting in wetland has a significant effect in nutrients removal. Experiment results indicated that there was significant difference between these wetlands in TN and NO3-N removed when the entire operation period was considered (P=0.005). But when each season was considered separately statistical differences were only observed during first summer after harvesting for TN removal. For NO3-N, differences between wetlands were observed in first summer and winter only. For summer, harvested wetland performed better than non-harvested wetland, but in winter non-harvested wetland performed better than harvested in terms of NO3-N removal. For winter, the reason to this could be that, some of plants parts decay and provided denitrification bacteria with a carbon source which accelerates denitrification process. According to this study, plants harvesting in wetland generally has a positive effect on nutrient removal such as TN, TP, COD, and BOD. Therefore, this practice could be recommended as the best wetland plants management to improve and maintain nutrient removal in constructed wetlands.