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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
411

Development of Sustainable Watershed Management Strategies for the Chiang-Chun River Basin

Lee, Mu-Sheng 05 August 2005 (has links)
In the process of pursuing economic growth as the national target for a long time, Taiwan has created an economic miracle but sacrificed ecological environmental sources. With increasing higher living standards, more living space is demanded such that providing clean and green spaces along riverbanks in addition to offering security becomes another important mission. In recent years, the global thinking of sustainable development has demanded more ecological and environmental protection such that efficient management of waters along river, drainage and seacoast will be emphasized tasks of watershed management. The main objective of pollution investigation and quantity estimation in Chiang-Chun River watershed is to effectively comprehend the sources of pollution to assist in establishing the water quality model to be used in simulation. The QUAL2E model developed by the US EPA is used to carried out estimating the carrying capacity of Chiang-Chun River, and drafting pollution control measures and waste reduction strategies so that the objective of improving Chiang-Chun River¡¦s water quality can be achieved. Chiang-Chun River has long been subjected to pollutions from industrial and domestic waste discharges resulting in serious water quality deterioration. Additionally the waste discharge from manufacturing plants along the creek has made the pollution even worse. Hence, various environmental protection authorities have actively promoted the checking and controlling industrial and pig-farming wastewater discharges and established a mechanism encouraging local residents to participate in the watershed pollution prevention and control. These measures will not only alleviate the water pollution in Chiang-Chun River with limited resources but also achieve the purpose of communing local residents and the river. V The livestock wastewater is currently treated in three-stage system including solid-liquid separation, anaerobic treatment and aerobic treatment. With good management, the effluent is expected to meet discharge standards. However, since most pig farmers, who may try to save costs, have not efficiently managed the treatment facility so that the treated effluent does not meet the standards. If directly discharged into surface bodies, the improperly treated effluent will cause serious pollution problems. A natural treatment and water purification system is currently being promoted. If implemented in the three-stage treatment system, the natural system (aquatic treatment system) will achieve energy savings, lower the difficulty to operate the treatment system and reduce the operation and maintenance costs. Additionally, effluent quality can be improved such that the possibility of water reuse is also expected. Providing adequate treatment for domestic wastewater requires the construction of sewage system, which is costly and may take a long time to complete. Additionally, since most residents are scattered in the watershed, the construction of conventional sewage system to collect domestic wastewater is not cost-effective. Hence, the natural system, e.g. constructed wetland, is proposed as the major method for treating the wastewater discharged from communities and for achieving water reuse such that multiple-functional benefits can be reached. Additionally, the concept and tasks of water pollution prevention and control can be deeply rooted in the community development so that a community possessing the capability of water self-purification and sustainable application is developed.
412

Analysis Treatment Efficiencies and Emergy Analysis of Constructed Wetlands¡ÐA Case Study of Kaoping River Old Railroad Bridge Constructed Wetland

Lu, Shih-min 02 February 2007 (has links)
Constructed wetlands have been widely accepted as a natural ecotechnology for wastewater treatment. Constructed wetland system is a treatment system, while it utilizes intertine relationship among water, plants, soils, microorganism and atmosphere in natural environment, and applies natural physics, chemistry and biochemical actions to remove pollutions natural. In addition, the constructed wetland can also to increase the areas to attract more wild animals as their habits. In this study, we analyzed quality of Koping River Old Railroad Bridge constructed wetlands to understand the remove efficiencies for different pollutions. The analytical results showed that A system of the constructed wetlands because some other sewage of A system flowed into the system. However, the treatment system were still better than those in B system. The average removal efficiencies of BOD5 ,COD ,NH3-N ,TP in A system equal to 81.93¢H,50.98¢H,74.89¢H,46,70¢H,respectively. However the average removal efficiencies of SS and Chlorophyll-a were increased for both A and B systems, which might because algae can grow vigorously in summer. Resulting in an increase for both Chlorophyll-a and SS. Besides, in autumn the litter effect of wetland plants might cause the concentrations of nutrients increased. In addition, in this study we also utilized emergy analysis to evaluate the economical values while comparing with a sewage treatment plant. The analytical results showed that the constructed wetlands could remove more pollutants than of the sewage treatment plant. However, the constructed wetland system could still increase the biodiversity. If they could reach steady treatment efficiencies under proper operation and maintenance. It is concluded that the constructed wetland system can provide advantages in both ecology and economics systems.
413

Pilot Study on the Treatment of Polluted River Water by an UASB Reactor followed by Constructed Wetlands

Wu, Cheng-Hsun 18 July 2007 (has links)
Abstract A system with the combination of upflow anaerobic sludge blanket (UASB) reactor and constructed wetlands (CWLs) has not yet been applied for cleaning river water polluted by sewage and swine wastewaters. In this study, a pilot system with an UASB reactor (effective working volume 4.0 m3) combined with two CWL reactors (effective working volumes 4.8 and 5.4 m3 for CWL-1 and CWL-2, respectively) was used to test the feasibility for treating wastewater sampled from the Wu-Luo River. The river is located in Ping-Tong County of southern Taiwan and has long been polluted by untreated domestic and partially treated swine wastewaters and is among the most polluted rivers in Taiwan. A control system without the UASB reactor and with the CWL-1 and CWL-2 was also tested in parallel to the test system. In the test system, the UASB reactor was seeded with an anaerobic sludge for sewage treatment and CWL-1 and CWL-2 of both the test and control systems were planted with emergent macrophyte (Typha angustifolia L.) and floating macrophyte (Pistia stratiotes L.), respectively. In general, it requires hydraulic retention times (HRT) of 1-5 days for polluted waters in CWLs to obtain clarified ones. In the present study, HRT of the test water in the system was reduced from around 34 to 11 hours to examine the clarification effect. Results indicated that the influent water has the following average qualities (unit in mg/L): total COD (CODt) 61, BOD 14, suspended solids (SS) 156, total-N 24, ammonia-N 12, nitrate-N 3.9, nitrite-N 0.92, and total-P (TP) 41. Results also indicate with a total HRT of 11.3 hrs, the test system (UASB-CWL1-CML2) could achieve average removals of 62% CODt, 56% BOD, 75% SS, 37% TN, 44% ammonia-N, 54% nitrate-N, 47% nitrite-N, and 61% TP from the influent water. The effluent water has the following average qualities (unit in mg/L):CODt 19, BOD 6.1, SS 15, TN 15, ammonia-N 7.5, nitrate-N 1.8, nitrite-N 0.49, and TP 1.7. The study indicates that the UASB could act as a preliminary device for sedimentation of most of the influent suspended solids and hence preventing the accumulation of sludge in the following CWLs.
414

Using Constructed Wetland for Industrial Wastewater Treatment

Lay, En-Hwa 18 August 2003 (has links)
Abstract Constructed wetlands can be treated as a imulated natural treatment system,which use solar adiation as the source of energy. By analogy with some removalmechanisms in natural wetlands, constructed wetlands are able to transform and remove pollutants from the wastewater. Other features provided by the constructed wetland include wildlife support, hydrologic odification, erosion protection, and open space and aesthetics. It has been applied for domestic wastewater purification for decades. The goal of this study was to evaluate the ffectiveness of using constructed wetlands on industrial wastewater treatment. In this study, grit chamber and furnace waste from steel-making were used as the media for plant growth. Two -tank (dimension for each tank: 4L ¡Ñ1W ¡Ñ1H) system was designed and constructed to simulate the constructed wetland. Reed and cattail were planted in the first and second tanks, respectively. In the system, media in the first and second tanks were filled to a height of 0.4 m (furnace waste from steel-making) and 0.1 m (waste grit), respectively. The depth of water was maintained at 0.3 m. The hydraulic retention time was approximately 5 days. The following parameters were analyzed during the operational period: nutrients, chemical oxygen demand (COD), suspended solids (SS), and biochemical oxygen demand (BOD). The calculated removal rates (g/m2/day) in the first tank were¡GCOD 5.92¡Ó0.64¡BBOD 3.48¡Ó0.95¡BSS (suspended solids) 3.42¡Ó1.44¡BTKN (total kjedal nitrogen, TKN) 0.94¡Ó0.26¡BTP (total phosphorus) 1.33¡Ó0.2¡CThe removal rates (g/ m2/day) in the second tank were: COD 5.17¡Ó0.62¡BBOD 3.21¡Ó0.92¡B SS 2.92¡Ó1.29¡BTKN 0.59¡Ó0.21¡BTP 0.66¡Ó0.15. Results from this study indicate that the media and plants in both tanks created a biofiltration system for microbial growth and pollutant removal. Sorption and biodegradation were the two major pollutant removal mechanisms in the system. During the operational period, the average removal efficiencies (%) in the first tank were: COD 55~62, BOD 73~90, SS 66~84, TKN 36~66, TP 28~39. The average removal efficiencies (%) in the first tank were: COD 49~54, BOD 73~83, SS 45~69,TKN 15~43, TP 9~24.
415

BOD5 removal in subsurface flow constructed wetlands

Melton, Rebecca Hobbs 29 August 2005 (has links)
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.
416

Application of constructed wetland on wastewater treatment

Chen, Zhong-Xun 02 September 2008 (has links)
Constructed wetland (CW) system is one natural purifying process. Using the CW systems to treat industrial wastewater or domestic sewage has been extensively application in many countries. Constructed wastewater treatment wetland must depend on the optimal operation parameters to achieve the best treatment efficiency. The objective of this research was to evaluate the effectiveness of Kaoping River Rail Bridge Constructed Wetland (KPCW) on contaminated river water treatment. The major influents came from the treated industrial wastewater from a paper mill [Yuen Foong Yu paper manufacturing company (System A)] and local drainage system (Chu Liao River) containing untreated domestic wastewater (System B).Results from this study show that the measured flow rates for Systems A and B systems were 10,968 and 13,147 m3/day, respectively. The hydraulic loading rates (HLR) and hydraulic retention time (HRT) for Systems A and B were 0.085 and 0.096 m/day, and 5.4 and 10.7 d, respectively. The average removal efficiencies for both systems ranged from 63.4-71.7% for biochemical oxygen demand (BOD), 39.5-44.4% for chemical oxygen demand (COD), 28.1-39.5% for ammonia nitrogen (NH4-N), 17.1-40.3% for total nitrogen (TN), 5.4-45.5% for total phosphorus (TP), and 91.1-98.7% for total coliform (TC). Reduction in suspend solid (SS) concentration was ineffective in both systems. This was due to the irregular harvest of the plants in the wetland. Results from the effluent probability method (EPM) evaluation indicate that the removal efficiency increased with the increase in influent pollutant concentration. Moreover, variations in pollutant loading rate (PLR) would affect both the removal rates and effluent concentrations. The experience obtained from this project will be helpful in designing similar natural water treatment systems for river water quality improvement for other river basins.
417

Identifying suitable sites for wetland mitigation at the watershed scale a GIS modeling approach /

Walsh, Kristal Cobb. January 2007 (has links)
Thesis (M.S.)--University of West Florida, 2007. / Title from title page of source document. Document formatted into pages; contains 114 pages. Includes bibliographical references.
418

Modelling meteorological and substrate influences on peatland hydraulic gradient reversals

Colautti, Dennis. January 2001 (has links)
A hydrological modelling effort using MODFLOW was undertaken in order to determine the relative importance of some of the factors influencing hydraulic gradient reversals in peatlands. Model domains were of two types, large raised bog type (LRBT) and kettle bog type (KBT), and were made to undergo various levels of meteorological forcing (water deficit). Substrate, too, was varied in order to determine its importance on reversals. Domain-wide reversals were successfully simulated in LRBT systems, but not in KBT systems. Although simulated flow patterns matched field-observed patterns, both pre- and post-drought, simulated reversals occurred more quickly than in the field. This may be due to insufficiently distributed parameters, such as hydraulic conductivity. Reversals were easily terminated by simulating non-drought conditions. In the LRBT system, reversal duration decreased, and time-to-reversal increased, with a decrease in drought severity. Increasing drought severity in KBT systems had the opposite effect on the duration of semi-reversed flow patterns, suggesting a possibly different/additional mechanism for flow reversals in KBT systems. Hydraulic conductivity had an appreciable effect on flow reversal evolution, though neither changing porosity, nor differences in catotelm layering had a great effect.
419

Reclamation of wetland habitat in the Alberta oil sands: generating assessment targets using boreal marsh vegetation communities

Raab, Dustin Jeremy Unknown Date
No description available.
420

Sedimentation and chemical processes on the Lower Mkuze floodplain : implications for wetland structure and function

January 2008 (has links)
The Mkuze Wetland System, situated in northern KwaZulu-Natal, is South Africa’s largest freshwater wetland area. The system plays a vital role in the functioning of the local landscape and has been identified as an important site for the retention of a number of solutes. The mechanisms through which this retention occurs were investigated through analysis of sediment, groundwater and porewater samples collected from the lower floodplain. Sample analysis was achieved through the use of several techniques, including Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), X-ray Diffraction (XRD), X-ray Fluorescence (XRF), electron microscopy and sequential extraction. / Thesis (Ph.D)-University of KwaZulu-Natal, Westville, 2008.

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