The risk of the Iraq’s marshlands disappearing is still high unless serious measures are adopted. Sewage discharge and irrigation-water pressure, compounded by the effects of climate changes and the extent of the planned dam construction in upstream countries, make this event more likely. Most of the marshlands’ inhabitants (Marsh Arabs) are suffering from lack of access to safe, clean water and lack of sanitation and are reluctant to look for better places to live and work. Constructed wetlands are among the best alternatives to solve their problems. The application of constructed wetlands to meet more stringent standards for wastewater reuse in agriculture contributes to mitigating the wastewater impact and irrigation pressure on the marshland ecosystem. It is here proposed that a 3.6 ha free-surface flow wetland  could manage the more stringent standard for reuse (15 mg/l) for BOD5 and TSS. A monitoring programme should nevertheless be associated with this kind of project to minimize health risks that may arise as a result of implementation. Despite the absence of studies that deal with wastewater reuse in irrigation projects at the national level (in Iraq), similar studies worldwide provide evidence of reuse possibilities. Furthermore, a performance requirements framework for wastewater reuse in irrigation projects such as the one suggested by Biswas, draws an approach to meet sustainable development indicators and would likely contribute to support and encourage the Marsh Arabs to settle back in their own areas.

The polluted agricultural wastewater, after reaching marine recipients, can cause eutrophication. This problem can be tackled and mitigated by using constructed wetlands as water treatment systems. The fact that constructed wetlands work through long periods of time has led many scientists to evaluate how long they can still treat their influents effectively. The development and growth of vegetation and the accumulation of nutrients on the soils in a wetland are expected to occur. These processes change the wetland efficiency to remove pollutants. In this study, a set of wetlands constructed to treat agricultural wastewater were analyzed in different periods to assess if there is a difference in removal efficiency of nitrogen and phosphorus. This assessment was performed by analyzing the retention rate, k and k20 values, which are variables that quantify the nutrients removal, in different periods of each employed wetland. Some of the observations demonstrated differences when comparing different periods of the wetlands. The nitrogen removal presented better performance in one of the employed wetlands when this was older. Another employed wetland has not shown a clear difference between different periods. In the wetlands with high vegetation densities, the nitrogen removal was more stable over consecutive years. The occurrence of oscillations in nitrogen removal was observed more often in the wetlands with the highest vegetation densities over consecutive years. The phosphorus removal presented no clear differences between different periods. The results suggest that the removal of nitrogen improves after wetland creation due to the growth of vegetation. In addition, they suggest that wetlands with high vegetation densities tend to oscillate the nitrogen removal more or less often according to the density of the vegetation due to the balance between denitrification and decomposition. Further, the results suggest that the removal of phosphorus remains unchanged over longer periods than the periods considered in this study (four to six years) due to the deposition of organic matter on the soils.

Eight agricultural catchments in south Sweden were investigated for factors that may affect phosphorus (P) load and retention in the downstream situated wetlands (WL). P load is known to affect retention, and is determined by hydrological and geographical catchment characteristics. The wetlands were small (0.02-0.88%) in relation to their catchments (CA) and varied in design. Net sedimentation and P retention was determined with sedimentation plates during one year. The variables that best explained differences in particles and TP retention were the hydraulic load (q), TP load and the wetland length to width ratio. Contrary to expectations there was no correlation between factors that could be associated with erosion (i.e. slope and soil clay content) and retention of neither particles nor TP. Generally, the highest amounts of settled particles and P were found close to the wetland inlets, but soil disturbance (i.e. tillage) and high q increased the settling distance. It was likely that the smallest clay particles were too unaggregated to settle within these wetlands. Factors not included, such as wetland vegetation and bioturbation may have a large impact on P retention and this should be further investigated. The study also points to the difficulties in scaling down geological and P loss data from a regional to a local scale, as there can be large local deviations from the regional standard values. An easy method for identification of local “hotspots” for P losses should be of value for planning the location of future wetlands.

Upflow anaerobic sludge blanket (UASB) has been developed and commercially used for treating high-strength wastewaters since 1971, and this process has been extended its applications to domestic sewage treatment since 1980. Constructed wetlands (CWL) can be treated as a simulated natural treatment system, which use solar radiation as the energy source. By analogy with some removal mechanisms 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 modification, erosion protection, and open space and aesthetics. It has been applied for domestic wastewater purification for decades. In this study, a pilot UASB-CWL reactor was built to test its performance for the removal of organic compounds and nutrients from a sewage with COD (Chemical oxygen demand) in the range of 200-300 mg/L. The UASB reactor has an active liquid volume of 2.5 liters and the CWL includes a 56 L-tank (CWL-1) followed by a 80 L-tank (CWL-2) in which emergent macrophyte (reed, Phragmites australis L.) and floating macrophyte (Pistia stratiotes L.), respectively, were planted. Effects of hydraulic retention time (HRT) of the test water in the reactor on the pollutant removal were tested. Results indicate that with HRTs of 2, 45, and 64 hours, respectively, in the UASB, CWL-1, and CWL-2, the system exhibited good performances for pollutant removal. The HRTs are equivalent to CODt loadings of 3.06, 0.065, and 0.026 kg/m3.day to the UASB, CWL-1, and CWL-2, respectively. Average total COD (CODt), soluble COD (CODs), total biochemical oxygen demand (BODt), suspended solids (SS), and phosphate-P (P) were 121, 62, 33, 130, and 0.10 mg/L, respectively, and these are equivalent to the removal efficacies of 45-65, 60-80,65-75, 30-50, and 85-95%, respectively. With the operation conditions, average CODt = 28 , CODs = 18, BODt = 10, SS = 18, NH3-N = 18, NO2--N =12 , NO3--N = 1.0, and P = 0.0 mg/L were obtained, and the average removal total efficacies were 93, 93, 90, 75, 72, 95, and 100%, respectively. Effluent qualities are far superior to the national effluent standards for domestic sewage in Taiwan.

In most cases, data from petroleum industry wetland studies indicate that treatment wetlands are equally or more effective at removing pollutants from petroleum industry wastewaters than from other types of wastewater. In this study, we discussed the treatment efficiencies of oil-refinery industry wastewater by pilot-scale constructed wetland systems .The constructed wetland systems were one free water surface system filled with the sandy media and one subsurface flow system filled with the gravel media operated in parallel. Each system planted with Phragmites communis. The hydraulic retention time for the treatment wetland was controlled in turn at 0.96, 0.48, and 0.72 days. The experimental results showed that all of these contaminants could be reliably removed from wastewater by treatment wetland, especially the FWS. The effluents from the constructed wetland systems reusing and recovering were feasible.

Thesis (M.E.S.)--The Evergreen State College, 2004. / Title from title screen (viewed 3/11/2010). Includes bibliographical references (p. 139-150).

No description available.

One of the main environmental problems associated with the disposal of waste on land is the release of liquid emissions from the site. This wastewater, known as leachate, is a product of the biodecomposition of the waste and filtrates from the landfill once the moisture saturation of the fill has been reached. The chemical composition of leachate is variable over time and between sites. Regardless of these variables, the main pollutants of concern in the leachate are ammonia and organics, both of which can cause environmental degradation in relatively low concentrations. Worldwide and in South Africa, leachate has either been directly released into the environment or into the local domestic sewage system. As more has been learned about the human and environmental health risks associated with these disposal methods, there has been a new focus in waste management toward treating the leachate at the source as part of the broader focus of sustainable landfilling. One of the treatment options being used is constructed wetlands (CW) due to the physical and chemical transformation mechanisms in these biological systems. This treatment process has been demonstrated to be effective as a final polishing treatment for leachate, and it is considered a technology appropriate in the South African context. Therefore the aim of dissertation is to ascertain the use of constructed wetlands as an appropriate treatment option for untreated methanogenic landfill leachate by determining the efficiency of ammonia and organic removal in a pilot-scale vegetated submerged bed (VSB) constructed wetland (CW) planted with Phragmites australis. During the 22-week treatability trial the VSB achieved an ammonia concentration removal efficiency of 91% and mass removal efficiency of 87%. Despite this substantial reduction of ammonia, the VSB was unable to achieve the required discharge standard. There were erratic fluctuations in both the treatment efficiencies for COD and BOO, and the results show no evidence of constant reduction of organics during the treatability trials. This is due to the refractory nature and the low biodegradability of the organics that remain in methanogenic leachate as suggested by the low BOO to COD ratio. Due to the low biodegradability of the organics, a biological treatment system, such as a VSB, will not be able to reliably meet the required discharge standards. Other passive treatment options or a combination of systems need to be explored in order to both satisfy legislative requirements and be appropriate in the South African context. / Thesis (M.Sc.)-University of Natal, Durban, 2003.

Orthophosphate removal from wastewater in a subsurface-flow constructed wetland (SFCW) was studied during the fall of 1995. The SFCW consisted of a cell with an impervious liner, filled with 1.27 to 3.81 cm river rock and planted with common reeds (Phragmites australis) and soft-stem bulrushes (Scirpus validus). Municipal wastewater was pumped through the wetland and comparisons were made between inlet and outlet orthophosphate concentrations. Comparisons were also made at locations within the cell. A mean orthophosphate reduction of 62% with a range of 91% to 32% was observed for the duration of the study. An ANOVA test showed a significant reduction of orthophosphate in the wetland cell during the study. A regression analysis indicated that inlet wastewater temperatures played a significant role in orthophosphate removal, while outlet wastewater and ambient air temperature were not a significant factor.Keywords: Subsurface-Flow Constructed Wetlands, Orthophosphate, Municipal Wastewater, Water Chemistry, Nutrients. / Department of Natural Resources and Environmental Management

The widespread practice in Latin America of separating greywater from blackwater at the domestic level lends itself to the application of Ecological Sanitation, or Ecosan. In this research simple, low-cost subsurface flow wetlands, or reedbeds, were investigated not only for their potential in treating the greywater component but also to evaluate their acceptance as an appropriate Ecosan technology in rural Central America. The hypothesis for this thesis is that Ecological Sanitation, namely via reedbeds for the treatment of greywater can improve sanitation in rural Central America. The first aim of this research determined that untreated greywater was having a significant negative impact on the water quality of the local streams of Monteverde in Costa Rica (the site of this research) and that the associated public health risks will continue to increase in line with population growth. Local residents expressed strong dissatisfaction with the current situation and were supportive of any means to improve it. The second aim of this research was to determine if reedbeds designed according to the principles of Ecosan could provide a healthier, affordable and more sustainable sanitation alternative suitable for rural areas. As a result five case study reedbed systems were designed and installed. All these reedbeds made use of locally available materials and incorporated low-maintenance design features, and research with a local plant species determined a robust macrophyte suitable for use in these systems. The ability of low-cost reedbed systems to successfully treat greywater was demonstrated. The Costa Rican guidelines for wastewater reuse were found to be overly restrictive in regards to fecal coliform limits (<1,000cfu/100mL) and may inhibit the wider uptake of reedbed systems if enforced. Despite this the uptake of the reedbed technology was strong and more than ten systems were installed in Costa Rica as a result of this research. An innovative environmental services contract, the first of its kind in Costa Rica, was developed to ensure on going funding for operation and maintenance of a four-household reedbed system. The third aim was to specifically investigate the use of waste plastic (PET) bottle segments as an alternative media in reedbeds to conventional crushed rock, or gravel. Twelve mini-reedbeds, or cells, incorporating PET media and plants as the two variables, were monitored through wet and dry seasons. This experiment demonstrated that reedbeds incorporating PET segments were able to achieve comparable removal of fecal coliform and BOD when compared to conventional media reedbeds, and at a significantly reduced cost. The local plant species Coix lacryma-jobi enhanced the performance of all reedbeds, most notably in the PET-based reedbeds, which was attributed to the considerably greater root biomass achieved in these systems as compared to conventional media systems. This research has demonstrated that reedbeds incorporating simple, low-maintenance design features are able to provide an affordable and appropriate technology for the treatment of greywater in rural Latin America.