Abstract not available.

Growing populations, urbanization, environmental awareness with resultant regulations and water scarcity have resulted in a search for alternative water sources. Municipal wastewater reclamation and reuse is a necessity in these conditions because it is a water source that is available throughout the year. It can reduce the demand for source water and could be treated at lower costs to the required water quality requirements of the intended use. South Africa especially the Gauteng Province is subjected to the above mentioned stressors but lacks a holistic approach to wastewater reclamation and reuse as a practical and viable solution. Furthermore, the lack of characterization parameters as well as advanced wastewater treatment methods and the viability assessments of the municipal wastewater generated in the South Gauteng catchment, has led to loss of potential water resource in the province. Therefore the current research was initiated as a baseline study to investigate the feasibility of municipal wastewater reclamation and reuse in the South Gauteng catchment. The specific objectives were to 1) assess the worldwide practices of wastewater reuse, 2) apply influent and effluent data analysis and make recommendations on the type of reuse application available for the Southern Gauteng municipal wastewater treatment effluent and to 3) assess the viability of tertiary treatment technologies as best fit options available for different reuse options required for the study area. To achieve the above mentioned objectives a literature review was undertaken to assess worldwide water reuse practices and how they can be used in the study area to utilize the generated wastewater effluent. Influent and effluent data of four wastewater treatment plants (WWTPs) in the Sedibeng district municipality (SDM), three in the Emfuleni local municipality and one in the Midvaal local municipality, was used to assess the viability of water reuse. Available worldwide aggregate, nutrient, ionic and microbiological water reuse standards and criteria for potable, agricultural and industrial use were used to characterize the Sedibeng WWTPs for water reclamation. Wastewater reclamation and reuse is broadly defined as collecting treated or untreated wastewater and using it for a purpose different from what it was used for previously. Recycling, on the other hand, is using water, for the same purpose repeatedly (DWA, 2013a). Water reuse is practiced in countries such as the Western United States, Australia, Singapore, Namibia, Mediterranean countries and Japan for potable use, irrigation and industrial purposes. South Africa, having laid the foundation of wastewater reuse in Namibia, currently practices direct potable reuse (DPR) in the Beaufort West municipality as well as internal water recycling in the power, steel, petrochemical, paper and pulp industry. Water reuse standards and criteria are set based on regional differences of water availability, public health protection, monitoring feasibility, industry types and the reuse purpose. Risk assessment that includes among others a multi-barrier approach, water quality criteria objectives and acceptance determines treatment technology selection. Tertiary treatment technology such as ultrafiltration, reverse osmosis and advanced oxidation processes especially UV/H2O2 are used in water reclamation plants after preliminary treatment of secondary effluent. The four SDM WWTPs effluent, which was over 220 ML/d, the results show, mostly use activated sludge process and have water quality determinants complying with the design criteria for advanced treatment in water reuse. This effluent meets the Namibian Goreangab and Beaufort West Water Reclamation Plant (WRP) multi-barrier influent design criteria for DPR in most aggregate, nutrient and ionic parameters except microbiological parameters. Parameters such as chemical oxygen demand (COD), dissolved solids and ammonia and alkalinity were non-compliant for which this could signify incomplete activated sludge process. This shows the importance of secondary treatment as one of the barriers in the multi barrier approach. Even though membrane treatment of this effluent to improve these parameters and microbiological quality is possible effective secondary treatment as one of the barriers is important to prevent downstream membrane fouling. Depending on this water quality the water will be suitable for indirect potable reuse (IPR) with blending, industrial cooling, heat exchange and dust suppression as recommended uses. Municipal effluent, which could reduce potable water demand, is currently not used in the study area’s power generation and steel making industries Eskom’s Lethabo power station and ArcelorMittal respectively. This is even though, advanced water treatment processes such as reverse osmosis, exist for both organization’s internal wastewater recycling. The reclaimed municipal effluent can be introduced to moderate water quality processes such as cooling systems, heat removal, waste handling and washing in both industries in the study area. Public-private partnerships (PPPs) with water intensive user industries incorporating municipal secondary effluent in current and future infrastructure plans to find viable solutions as part of their water use licensing conditions. These PPPs would include the national Department Water and Sanitation (DWS), Sedibeng district municipality, Eskom, ArcelorMittal and Rand Water the bulk water utility in the study area. An in depth study of water reuse public perception, cost of water reuse, establishing purpose specific reuse guidelines and water quality monitoring and management plan for study area is recommended before implementation. Monitoring, which is one of the barriers in risk abatement, should include for the study area emerging pathogens, inorganic and organic contaminants of concern such as endocrine disrupting chemicals (EDCs). / Dissertation (MSc)--University of Pretoria, 2016. / Centre for Wildlife Management / Unrestricted

No description available.

I analyzed lake fertilization (with nitrogen and phosphorus) as a tool to assist in the recovery of the Snake River sockeye salmon (Oncorhynchus ~) in the oligotrophic Sawtooth Valley Lakes in southcentral Idaho. These analyses involved monitoring, manipulating, and modelling several aspects of the lakes' primary producer, nutrient, and light parameters. In Pettit Lake, I evaluated the effects of metalimnetic and epilimnetic fertilization in 330-m 3 mesocosms. The metalimnetic treatment was equal to or more effective than the epilimnetic treatment in increasing chlorophyll a, phytoplankton biovolume, and primary productivity, yet caused smaller changes in periphyton growth and water clarity. Thus, metalirnnetic fertilization may provide a tool for increasing lake productivity while minimally impacting water clarity. The Sawtooth Valley Lakes had deep chlorophyll maxima (DCM) with mean chlorophyll a peaks 240-1000% of mean epilimnetic concentrations. The DCM existed at low light levels and accounted for 36- 72% of the lakes' primary production. Epilimnetic fertilization of330-m 3 mesocosms in Redfish Lake increased levels of primary productivity and chlorophyll a, but decreased Secchi depths and light available in the meta- and hypolimnion. I modelled the effects of increased chlorophyll (resulting from epilimnetic fertilization) and decreased light penetration on vertical primary productivity profiles. The simulations showed a large increase in epilimnetic primary productivity due to fertilization, and only a slight decrease in production in the deeper strata due to self-shading. I also modelled the dependence of Red fish Lake's production on nutrients from the watershed, from lake fertilization, and from marine-derived nutrients from salmon. The model utilized our water budget and nutrient loading measurements. The model and empirical evidence indicated that even before hydropower dams were present in the migration corridor, marine-derived nutrients were not of major importance to lake production, contributing only ~3% of the lake's annual phosphorus load. This contribution was partially offset by the lake's quick flushing rate (3 yr) and phosphorus export by smolts. The model predicted annual adult salmon returns to be 3,800 under pre-dam conditions, 370 under modern conditions, 750 when doubling watershed nutrient loading (simulating lake fertilization), and 780 when doubling migration survival.

No description available.

Irrigation water allocation is essential to the management of agricultural water use in irrigation districts. Many irrigation optimization models were proposed from previous studies to provide decision support for water managers. In order to capture the complex nonlinear relationships and meet different water demands, more advanced multi-objective nonlinear programming models were developed in the past decade. However, it is still a challenging task to address varies uncertainties associated with irrigation optimization. Fuzzy programming, interval programming, and chance-constrained programming can be used to quantify uncertainties in simplified formats, but none of them can represent complex uncertainty in a composite format. In this thesis, a cloud-based dual objective nonlinear programming (CDONP) model is developed by implementing a cloud modeling method in an irrigation model to address the uncertainties of reference evapotranspiration (ET0) and surface water availability (SWA). The cloud modeling method is used to generate 2,000 data samples from historical data. The results show that the generated samples are consistent with historical data. Optimized allocation schemes are provided, and the performance of the CDONP model are discussed. This is the first Canadian study that used the cloud modeling method in irrigation water allocation. This method provides a solution to quantify composite uncertainties based on limited data, which represents a unique contribution to irrigation water allocation modeling. This study provides valuable decision support for agriculture management to improve water use efficiency. / Thesis / Master of Applied Science (MASc)

No description available.

Fecal contamination in estuaries has become an increasing concern worldwide. The use of wetlands for wastewater treatment has expanded due to their natural ability to improve water quality by removing suspended sediments, nutrients, and fecal bacteria. In general, most of the removal occurs through deposition and accumulation in the wetland substrate. This would suggest that wetlands are effective filters for fecal coliform transported from terrestrial environments to surface waters. It has also been hypothesized, however, that wetlands may be an intermittent source of fecal coliform in tidal systems as a result of wildlife deposition and /or accumulation from terrestrial sources. To investigate the role of tidal wetlands in fecal coliform loadings from small estuarine systems, this project examines the difference between monitoring data and modeling data for shellfish growing areas in Virginia. Results suggest that models should treat tidal wetlands as discrete components of contributing watersheds, rather than assuming they can be grouped with forested land areas. Tidal wetlands’ role in fecal coliform transport could be embodied through the net sediment transport between tidal wetland and adjacent coastal water. When the tidal wetland substrate is resuspended, what happens to the water quality? Do tidal wetlands contribute to and how they contribute to the high amount of fecal coliform (FC) in shellfish harvesting zone? To address these questions, Loading Simulation Program C++ (LSPC) and a hydrodynamic model - Tidal Prism Water Quality Model were used to simulate fecal coliform transport through the watershed (including wetlands) and coastal waters with the support of the project of Development of Shellfish TMDLs for Virginia. The error analysis, that is the discrepancy between the model prediction and observation data, will then be used to explore the sinks and/or sources of fecal pollution in tidal marshes. Seasonal variation of fecal coliform concentrations in shellfish growing water and model sensitivity tests will be analyzed and discussed surrounding this issue.

No description available.

Heat-as-a-tracer has become a common method to quantify surface water-groundwater interactions (SW/GW). However, the method relies on a number of assumptions that are likely violated in natural systems. Numerical studies have explored the effects of violating these fundamental assumptions to various degrees, such as heterogeneous streambed properties, two-dimensional groundwater flow fields and uncertainty in thermal parameters for the 1-dimensional heat-as-a-tracer method. No work to date has addressed the impacts of non-uniform, three-dimensional groundwater flows on the use of heat-as-a-tracer to quantify SW/GW interactions. Synthetic temperature time series were generated using COMSOL Multiphysics for a three-dimensional cube designed to represent a laboratory setup of homogeneous, isotropic sand with a sinusoidal temperature variation applied to the top. We compare temperature-derived fluxes to model-generated fluxes to assess the performance of methods using temperature to quantify 1D vertical fluxes in response to multi-dimensional groundwater flows. Both increasingly non-uniform and non-vertical groundwater flow fields result in increasing errors for both amplitude-ratio-derived groundwater flux and temperature-derived effective thermal diffusivity. For losing flow geometries, errors in temperature-derived effective thermal diffusivity are highly correlated with errors in temperature-derived flux and can be used to identify if underlying assumptions necessary for heat-as-a-tracer for quantifying groundwater flows have been violated. For this model set-up, when groundwater flows are non-uniform, the thermal method generally calculates fluxes outside the range occurring between temperature sensor pairs. When errors are low (15% of flux calculations), temperature derived fluxes more closely match the minimum magnitude flow occurring between the sensors.