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)

Thesis (M. L. A.)--University of Hong Kong, 2007. / Includes special report study entitled: Water level control technology in constructed wetland. Title proper from title frame. Also available in printed format.

Five unique but related studies were conducted at the Oregon State University Dairy Wetland Treatment System (OSUDWTS), Corvallis, OR. The research site consisted of six parallel wetland cells, which were built in 1992 and began receiving concentrated dairy wastewater in the fall of 1993. Hydrologic, hydraulic, and water quality data were collected at the site for three years. The five resulting studies were: 1. the prediction of evapotranspiration (ET) from wetlands; 2. the development of a hydrologic model and water budget for the OSUDWTS; 3. a preliminary investigation of the hydraulics of the OSUDWTS; 4. an overall evaluation of the treatment performance of the OSUDWTS and applicability of current constructed wetland design methods to livestock wastewater wetlands; and 5. the development of a conceptual model for nitrogen removal in constructed wetlands. Average ET rates for the wetland cells were found to be 1.6 times as great as the Penman- Monteith alfalfa reference ET. Specific crop coefficients were 1.72, 2.32, and 0.57 for bulrush, cattails, and floating grass mats. The detailed hydrology model predicted daily water levels very accurately (R��=0.95) and showed seasonal rainfall and ET could increase or decrease the average detention time by as much as 18%. Tracer studies indicated that non ideal flow existed in the wetlands. Actual detention times were found to be an average of 43% shorter than theoretical detention times. Tank-in-series and plug flow modified by dispersion models were inadequate at describing the observed tracer response. Constructed wetlands were shown to be able to reduce a high percentage of most waste constituents in concentrated livestock wastewaters. Average reductions for COD, BOD, TS, TSS, TP, TKN, NH��� and fecal coliforms were 45, 52, 27, 55, 42, 41, 37 and 80%, respectively. Rate constants for volumetric and areal first-order plug flow models were found for each wastewater constituent. Overall, both models were fair at predicting wastewater reduction at the OSUDWTS. A conceptual model of nitrogen cycling showed denitrification to be the most important process for nitrogen removal in constructed wetlands. However, low dissolved oxygen in constructed wetlands limits nitrification, which in turn limits denitrification. / Graduation date: 1997

Thesis (M.S.)--University of Delaware, 2007. / Principal faculty advisor: Jacob L. Bowman, Dept. of Entomology & Wildlife Ecology. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 169-180).

Conscious governments in the developing countries try to keep abreast of developments, by offering better services to their citizens; one of the important services is to preserve the natural water resources. Implementation of constructed wetlands part of sustainable water resource management and ecosystem is a new approach for water treatment and biological disposal of contaminants, therefore families can contribute to these treatments through the use this system in their houses.  In order to meet the demand of daily water consumption by separating greywater from wastewater and for its reuse after treatment constructed wetland systems are one of the successful ecological treatments to reduce the concentration of pollutants in greywater. In view of the acute water crisis supply in Iraq, the best solution found for covering the daily consumption of householders is to apply the constructed wetland for treatment of greywater. The implementation of green roofs technique is one of the best ways to intercept rainwater. Especially in Iraq, where this technique can be used to provide thermal insulation, and an appropriate environment, to use the roofs for sleeping at night in the summer season.

Due to various components within the landfill sites, the water qualityof landfill leachate, which has high consistency of COD, BOD and nutrients, is unsteady. Using traditional sewage treatment plant to treat leachate should be designed and built to fit the unsteady water quality, which is usually time consuming and high expenditured. Therefore, application of constructed wetland treatment systems as altanatives may solve such kinds of problems According to the experimental results of this study, referring to the effect of cleaning the controlling substances, the SSF (sub-surface flow system) constructed wetland system performed better than the FWS (free-water surface system) one, which was because FWS was usually operated in an opening water areas, which exposured to the air causing stink in the inflow site of influent, and meanwhile caused problems of virus-transmitting mosquitoes. . Thus, it was suggested to use SSF system in treating landfill leachate. In this study, we found that the average removal efficiencies of pollutants in the leachate were high in the constructed wetland systmes (phosphate 73%, total phosphorous 70¢H, total nitrogen 57%, NH3-N 77¢H, COD 43% ). In addition, the BOD in the effluent from the systems could reach the outflow standard guideline in Taiwan (30 mg/L). Hence, using constructed wetland systems to solve those problems arisen from landfill leachate is expandable. We also found that the aquatic plant species of reed (Phragmites australis) that we used in this study could not grow well and was invaded by aphid due to the limitary environment in the landfill site and lack of biodiversity, which could not generate a good natural food chain. On the other hand, it was found that the plant species of evergreen (Dracaena sanderiana) could grow healthily and present high removal efficiencies for pollutants. Since the leachate was lack of biodegradable organic carbon sources used for denitrification, in the final test run of this study, we run an experiment of adding organic carbon sourcecs (fructose and molasses) into the constructed wetland systemis to test its effect on denitrification. The experimental results showed that the addition of organic carbon sources could significantly increase the efficiencies of denitrification to let more nitrate removed from the leachate, especially for molasses, which could increase the denitrification efficiency above 90%.

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 wastewater. In this study, a pilot system with an UASB reactor (effective working volume 2.5 liters) combined with two CWL reactors (effective working volumes 54.4 and 80 liters for CWL-1 and CWL-2, respectively) was used to test the feasibility for treating wastewater samples prepared by mixing 1 volume of sewage and 1 volume of partially-treated swine wastewater. In the system, the UASB reactor was seeded with an anaerobic sludge for sewage treatment and CWL-1 and CWL-2 were planted with emergent macrophyte (reed, Phragmites australis L.) and floating macrophyte (Pistia stratiotes L.), respectively. Effects of hydraulic retention time (HRT) of the test wastewater in the UASB reactor on the removal efficacy of various pollutants were tested. HRTs of 6, 4, and 2 hours were set for the UASB for the first, second, and third experimental phases, respectively. The tested influent wastewater had the following properties (unit in mg/L and the number in parentheses indicates the average value): total CODt 64-332 (179), soluble CODS 28-267 (129), soluble BODS 8-120 (70), SS 110-1330 (372), NH3-N 20-99 (48), NO3--N 1.2-11.9 (2.7), NO2--N 0-3.4 (1.0), total nitrogen TN 24.3-95.7 (56.8), PO43--P 0-10.4 (2.9), total phosphorus TP 5.1-52.1 (23.9), Cu 0.0-0.41 (0.13), Zn 0.05-0.73 (0.27), DO 0.2-2.7 (0.7), and pH 6.9-7.7 (7.4). Effluents from the UASB reactor for the third phase test had average values of CODt 55, CODS 40, BODS 27, SS 93, NH3-N 42, NO3--N 2.6, NO2--N 0.5, TN 43.7, PO43--P 0.9, TP 17.2, Cu 0.08, Zn 0.07, DO 0.04, and pH 7.4. For the phase, effluents from the combined UASB-CWL1-CWL2 system had average values of CODt 21, CODS 16, BODS 10, SS 38, NH3-N 2, NO3--N 1.9, NO2--N 0.1, TN 11.3, PO43--P 2.6, TP 5.9, Cu 0.06, Zn 0.05, DO 5.4, and pH 7.6. The system has been shown to be economically and technically feasible for cleaning the test wastewater.

The Wu-Luo River located in the Ping-Tong County of southern Taiwan has long been polluted by untreated domestic and partially treated poultry wastewaters and is among the most polluted rivers in Taiwan. A full-scale constructed wetland (CW) has been in operation since January of 2005 for cleaning a part of the polluted river water. The purpose of this study was to investigate the specifications of the CW and its performance for removing both organic and inorganic pollutants form the influent water. Results indicate that during the investigation period of April 2006 to February 2007, the CW had channel widths of 86-112 m (average 100 m) and a zone-type length of 1,600 m. It occupied a total area of 18 hectares in which around 9 hectares were wetted by the introduced river water. Around 4.7 hectares of the CW was flooded by the river water and 1.9 hectares were occupied by emergent and floating plants such as cattail, water lettuce, reed, water celery, and bara grass. A total water volume of around 6,800 m3 was estimated. In the period, 10,000-20,000 m3/day (CMD) (average 10,800 CMD) of the polluted river water was introduced to the CW and a hydraulic retention time (HRT) of 0.63 day was estimated for the flowing water in the through the water body. Results also indicated that the influent water has the following qualities (unit in mg/L except pH and number in parentheses indicates the average value): total COD (CODt) 10-121 (52), BOD 6-36 (21), suspended solids (SS) 10-165 (70), pH 5.4-8.1 (7.4), ammonia-N 2-22 V (13), nitrate-N 0-9.4 (2.5), nitrite-N 0-1.8 (0.2), total-N (TN) 9.9-41.3 (22.6), phosphate-P 0-3.1 (0.9), total-P (TP) 1.2-36.7 (5.2), Cu 0.022-0.60 (0.071), and Zn 0.01-0.36 (0.13). It was found that water sampled from nearly the middle point of the CW got better clarification results than that from the effluent end. Pollutant removal efficacies were 60, 60, and 67%, respectively, for CODt, BOD, and SS at the middle point, while 56, 54, and 45%, respectively, for CODt, BOD, and SS at the effluent end. Organics, N, and P released from rotten plants were responsible for the poor water qualities at the end. The CW had only a TN removal efficacy of around 18% and no TP removal effect.

ABSTRACT Coast zones are ecology sensitive areas, coastal wetlands may provide many biological, chemical and physical functions. However, as a result of economy develops, it makes many industrial estate and large-scale reclamation along the coast, the coastal wetlands are facing critical threatens, includes of habitat loss, industrial wastewater, wetlands degradation , fishery reduction and coastal zones erosion. In order to achieve the sustainable use of coastal resources and pure industrial wastewater and provide wildlife habitat, creating or restoring wetlands may resolve many problems in Taiwan¡¦s coastal zones. Coastal wetlands restoration, enhancement, and creation can clear up wastewater, increase wetlands and slow environmental destruction. Coastal wetlands also achieve recreational, educational , cultural functions, environmental education, and sustainable development of Taiwan¡¦s coastal zones. This thesis collect constructed wetlands history, and application cases, aim at the sensitive coastal in Taiwan to suggest constructed wetlands strategies. Keywords: Coastal Zone, Wetland, Constructed Wetland, Taiwan.