The main contents of campus sewage are BOD and inorganic nutrients. Conventional secondary treatment processes can remove BOD efficiently, whereas the inorganic nutrients remain mostly left. Therefore, the effluents may cause eutrophication to the receiving water bodies. Using constructed wetland treatment system to reduce nutrients become more and more popular recently. Vertical flow type subsurface process is particularly efficient in nitrogen transformations. In this research we studied the nitrogen transformation dynamics by using different types vertical flow constructed wetland system with various natural materials as the media to treat the secondary effluents from a campus sewage treatment plant. Six self designed experiment columns with broken concrete blocks, oyster shells, different sizes of marble granules, and river sands were used for this study as vertical flow constructed wetland systems. The methods of operation included batch type, continuous flow with filled water and trickling filter type, which were tested by controlling the influent flows into those six test columns. The efficiencies of various combinations in treatments and their mechanisms were discussed in the study. The experimental results showed that the best ammonium nitrogen removal efficiency was measured equal to 46.6% in batch type operations, while the continuous flow with filled water type operation showed the best performance by using concrete blocks as the media (42.8%). However, the best ammonium nitrogen removal rate in the trickling operation was found in the column with media of 3 mm marble granules (91.1%). The medium of river sand obtained the best phosphorous removal rate by using a batch flow operation. Vegetating presented only minor contributions in the column with medium of smaller grain size materials. The optimum C/N ratios for denitification tests are 3.5 and 3 by using the media of concrete and oyster, respectively.

Constructd wetland system is one of the ecological engineering technologies used on wastewater treatments. In this study, we discussed the treatment efficiencies of oil refining and steel-milling wastewater by four lab-scale constructed wetland systems (0.8-m long by 0.4-m wide by 0.7-m deep), which were all filled with gravel media, and planted with Phragmites communis. The constructed wetland systems were designed into two types: free water surface (FWS) and subsurface flow (SSF) wetland systems, which were discharged with two different types of wastewater (oil refining and steel-milling). The experiments of this study were run by five stages. The experimental results showed that almost all of the contaminants could be reliably removed from wastewater by the constructed wetland systems, especially in the SSF systems. During the experiments, the second stage of the experiments had the best treatment efficiencies, in which the flowrate was controlled at 5mL/min. The hydraulic retention time (HRT) in FWS and in SSF werecalculated equal to 7.5days, and 5.36days, respectively.

In recent years, interest in wastewater treatment through constructed wetlands has been significantly increased because of their low cost and energy requirement. In this study, pilot-scale constructed wetland systems were developed to evaluate the efficacy and effectiveness on the treatment of oil-refining and steel-milling wastewater. The constructed wetland used to treat the oil-refining wastewater included one free water surface system (FWS) filled with sandy media and one subsurface flow system filled with gravel media. The plants grown on the wetland were Phragmites communis. The hydraulic retention time for the two systems was approximately 7 and 5 days, respectively. A two-stage subsurface flow constructed wetland system was used to treat steel-milling wastewater. This system, which filled with gravel media were planted with Phragmites communis (the first stage) and Typha orientalis (the second stage). The hydraulic retention time for this system was approximately 7 days. Experimental results showed that the two constructed wetland systems for the oil-refining wastewater treatment could remove most of the wastewater pollutants. Moreover, the first system (FWS) played a more important role on the wastewater treatment. The efficiency of the first stage of the wetland system, which was used for steel-milling wastewater treatment was not significant due to the inhibition of the plant growth by the wastewater. However, the treatment efficiency was increased at the second stage after planting new plants. Results from the two-stage treatment system indicate that higher treatment efficiencies were observed except for ammonium. Results from this study would be very useful in the design of constructed wetlands for practical application to treat oil-refining and steel-milling wastewaters.

Cultivation and drainage projects associated with livestock production have substantially disturbed resaca wetlands and wet prairie habitats in southern Texas. As a consequence of the anthropogenic disturbances, the area of these wetlands has been reduced and the ecological integrity of the remaining wetlands has been compromised. The goal of this study was to explore effective strategies for ecological restoration of coastal prairie and resaca ecosystems in south Texas and provide restoration recommendations to the National Park Service at Palo Alto Battlefield National Historic Site (NHS). Field experiments were conducted to evaluate the effectiveness of different approaches for restoring Spartina spartinae on disturbed saline flats. A resaca hydrologic study was initiated to evaluate the groundwater hydrology in disturbed versus undisturbed resaca wetlands and explore potential restoration strategies. Transplanting S. spartinae in the fall season was more successful (80% survivability) than seeding (0% initial establishment), spring transplanting (0% survival), spring and fall mechanical transplanting (0% and 6% survivability, respectively). Soil disturbance significantly affected (p < 0.05) survival of transplanted tillers and basal diameter of both the bare root and container-grown transplants in the fall manual treatments. The initial hydrologic study of the resaca wetlands found that vegetation rooting zone hydrology was likely dependent on surface water rather than groundwater. These findings suggest that strategies that restore surface hydrologic regimes will likely restore the ecosystem structure and function of disturbed resacas. Manually transplanting bare-root stock of S. spartinae in the late fall season without soil disturbance will increase the likelihood of successful saline flat restoration.

Recently, the use of constructed wetlands to treat nutritions and containing wastewater, has quite been in vogue. However, since salts aquacultural wastewater contains massive nutrients and salts, the common aquatic plant species are not suitable to treat it. Therefore the purpose of this research is mainly to use pilot-scale salty water constructed wetland systems operated under batch conditions to removal efficiency of nutrients. The pilot-scale have nine pools, the influent was from discharge channels containing aquacultural wastewater and community sewage near by Dapeng Bay. The experiment designs altogether has four stages.In the first stage to the third stage, the HRT was continued at 7 days. Last stage, the HRT was continued at one month. Experimental period has used waste brick bat, oyster shell, 9mm stone and mix stone (9mm stone and 3mm stone mix) as filter medium. The 9mm stone pool and mix stone pool coordinates differently to test the stage planter differently to plant the species. The plant aspect has Avicennia marina(L2¡BL3 pool ), Lumnitzera racemosa and Phragmites australis. (First, the second stage plants the Phragmites australis , the third stage starts to plant Lumnitzera racemosa). The experimental results showed that the filter media used with the mix stone presented the highest removal efficiency for the nutrients,whice the oyster shell exhibited the lowest removal efficiency for the nutrients. The oyster shell system was also found nutrients releaseal to the system. For using plants to remove the nutrients, we found that plants, did not show better performace than the systems without plants(p¡Ö0.05). However, for the condition of vegetation, the plant species of Avicennia marina exhibited the best performace.

Constructed wetlands had been used for water treatment worldwide. The efficiency of wastewater treatment in a constructed wetland depends on its design, types of aquatic plants and microbial community present in this wetland. The goal of this study is to analyze the microbial populations in KaoPing River Rail Bridge constructed wetland which was designed to remove the polluted material from municipal sewage and industrial wastewater. Sediment and water samples were collected every 3 months from April, 2007 to April, 2008. The bacterial community diversities were analyzed by PCR-DGGE of the bacterial 16S rRNA gene. Results show approximately 60% BOD, 41% COD, 46% nitrate, 22% total nitrogen, and 97% coliforms were removed by this wetland system. DGGE profiles revealed the bacterial community diversities shifted progressively from the entry to the exit of both A and B systems in this wetland. The microbial populations in water, sediment, biofilms on plants, and soil were quite different from each others. The fecal indicator Escherichia coli was used as a marker to monitor the fecal contamination in all samples. From PCR-DGGE profiles, E. coli could be successfully removed by this wetland system. In conclusion, this constructed wetland is a very successful system for wastewater treatment and is able to remove most of the pollutants before they are discharged into KaoPing River. The results of this study provided useful suggestions for the government to assess the bacterial diversities and the efficiency of this wetland system, to protect people from hazardous risks, and to manage a constructed wetland in the future.

It is an internationally acknowledged that marine protected area (MPA) is an important measure for maintaining biodiversity and rescuing endangered species. MPA can also effectively inhibit human interferences such as development and pollution discharge. The establishment of MPA is possible to fulfill the goal of sustainable management, which is to conserve marine habitat for an integrative ecosystem and a higher biodiversity. However, how to design an effective MPA remains an important research issue to be explored. In order to grasp the spatial distribution of the ecological data in the study area, the current research uses spatial interpolation tool, Kriging, provided by the Geographic information system (GIS) software. Then three spatial analytical models have been developed based on integer programming techniques. It is guarantee that all three models can find the global optimal solutions for the best protective area partitions. This quantitative approach is more efficient and effective compared to the qualitative methods in many aspects. The models are able to preserve the maximum ecological resources under the limited spatial area. Besides, the model formulation can be adjusted from different environmental impact factors to fulfill the requirements of users. The case study of the research is to design a MPA for Kaomei wetland. However the spatial analytical models developed in this research can also be applied to protected area design in land area.

<p> </p><div><table style="height: 340px;" border="0" cellspacing="0" cellpadding="0" width="639" align="left"><tbody><tr><td style="padding: 0cm 7.1pt;" height="289" align="left" valign="top"><div style="border: 1pt solid windowtext; padding: 1pt;"><p class="MsoNormal" style="border: medium none; padding: 0cm;"><span style="font-size: 10pt;" lang="EN-GB">A low-loaded constructed wetland was investigated with respect to phosphorus retention. Since the main long-term phosphorus retention mechanism is sedimentation and sediment accretion, the study focused on these processes. The purpose of the study was 1) to investigate how the calculated value of phosphorus retention (P_in – P_out), corresponded with the measured amount of phosphorus in the sediment, 2) to find out where in the wetland the phosphorus had accumulated, and in what form it was retained, and 3) to investigate the role of vegetation. The calculated value was 12 kg ha^-1 and the measured value was 104 kg ha^-1, which indicated the importance of internal phosphorus circulation, where plants probably take phosphorus from the underlying clay. Hence, vegetation could possibly increase the total phosphorus content in the wetland. The composition of phosphorus in the sediment was analysed using sequential fractionation. The dominating form of phosphorus in the sediment was iron-bound phosphorus (29 %). In total, 48 % of the phosphorus was stable, i.e. tightly bound in the sediment, and 35 % was relatively stable. The bioavailable fraction, which could cause eutrophication in downstream waters, was 17 % of the total phosphorus content, or 41 kg ha^-1. The amount of total phosphorus was significantly higher near the inlet, compared to the outlet, which is explained by rapid sedimentation of particulate phosphorus entering the wetland. The phosphorus amount near the inlet represented 80 % of the total phosphorus load – which indicates the importance of internal circulation of phosphorus, both biological and geochemical. </span></p></div></td></tr></tbody></table></div>

Thesis (M.S.)--Mississippi State University. Department of Agricultural and Biological Engineering. / Title from title screen. Includes bibliographical references.

Plants (macrophytes) growing in lake and wetland sediments are known mediators of greenhouse gases (GHG), specifically methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O). Current studies have emphasized the potential risk of underestimation regarding emissions of plant-mediated GHGs from terrestrial systems including lakes, streams and other freshwater bodies. In order to differentiate the possible sources and sinks of atmospheric carbon and nitrogen in aquatic environments, this study aims to investigate the spatial variability of GHG fluxes in stands of common wetland macrophytes. Field samplings were carried out in the summer of 2012 where 24-hour diel measurements were conducted with the static chamber method in a boreal lake in south western Sweden. Two macrophyte communities were studied; one mixed-species stand and one species-specific stand of water horsetail (Equisetum fluviatile). Spatial variability was confirmed at several stages, both between and within stands. The species-specific stand emitted more CH4 than the mixed stand, from 0.17 to 8.99 mmol m-2 h-1, compared to 0.63 – 1.95 mmol m-2 h-1 maximum measured. Within stand variability was confirmed as variable CH4 flux per strand of E. fluviatile was established. No significant differences were observed regarding CO2 and N2O, other than weak correlation in diel patterns, e.g. daytime uptake and night time respiration/emission for both gases.