M.Ing. / The Rietvlei Water Treatment Plant was extended with a granular activated carbon (GAC) filtration system after an exhaustive series of tests, which were started in 1994. Upon commissioning towards the middle of 1999, a year of close monitoring followed to measure the GAC performance at full-scale. After verification that the GAC does indeed ensure a high quality product under all conditions, the emphasis shifted to the optimisation of the GAC handling and regeneration system. Frequently moving the entire GAC inventory from the filters to an off-site regeneration plant and back requires significant operational effort and contributes a major part of the total cost of the GAC system. A number of systematic investigations were carried out in response to a number of practical questions that arose at Rietvlei. The first part of the study was directed towards tracking and quantifying the GAC on and off site. The main findings were that 10.0% of the GAC is lost from the filter during backwashing (0.3%) and removal of GAC from the filter for regeneration (9.7%). The sump traps not all this GAC and 2.3% of the total inventory is lost to the river. Inserting a sieve at the outlet of the sump can eliminate this loss. A further 80.3% of the GAC in a filter is removed for regeneration, of which 18.7% is lost during the regeneration process. The minimising off this loss can only be achieved through the optimisation of the regeneration process, which falls within the domain of the regeneration contractor. The second part of the study was directed at the behaviour of the GAC whilst within the filter bed. The porosity and sphericity was determined by laboratory tests and calculations. The porosity was found to be 0.69 for the 12 x 40 size carbon and 0.66 for the 8 x 30 size carbon and the sphericity was found to be 0.67 for the 12 x 40 size carbon and 0.66 for the 8 x 30 size carbon. By using a calibrated bed expansion model, the bed expansion could be calculated at 9°C and 23°C for the two carbons gradings; the maximum temperature range experienced at Rietvlei. The main finding of this part of the study was that the average available freeboard is 650 mm for the 12 x 40 grading and 430 mm for the 8 x 30 grading, and therefore no GAC should wash over the weir at all during backwashing. The third part of the study measured the physical changes of the GAC found at different points in the GAC cycle. The main findings were that the small fraction of GAC washed out of the bed during backwashing and removal has a finer grading, higher apparent density and lower adsorption capacity than the GAC in the filter bed. There seems to be no marked attrition of the carbon or generation of fines during the removal and transport of the GAC to the regeneration plant. After regeneration, there was a 7% decrease in apparent density and a 30% increase in adsorption capacity. The final part of the study correlated the adsorption capacity of the GAC with its time in use as well as UV254 removal. After regeneration, UV254 removal begins at approximately 20% and declines to 14% after 400 days of operation, and to 10% after 600 days. After regeneration, the iodine number begins at approximately 800, declines to 600 after 400 days of operation, and to 500 after 600 days.

Magister Philosophiae - MPhil / The Lesotho Highlands Development Authority routinely uses the South African Scoring System version 4 (SASS4) in conjunction with water chemistry to monitor water quality of rivers in the Lesotho Highlands Water Project areas. The objective of this study was to test the efficiency of SASS4 in these areas. / South Africa

M.Sc. (Chemistry) / Water purification technologies based on membranes are prone to fouling by natural organic matter (NOM) and other biological species in water. This leads to the short lifespan of the membranes and high demand in energy than normal due to high pressure needed to pump water across the fouled membrane. In a quest to address these challenges, polyethersulfone (PES) and polyvinylidene flouride (PVDF) membranes supported on 3 different types of non-woven fabrics NWF1(polyester), NWF2 (polyphenylene sulphide) and NWF3( thicker polyester) were fabricated using the phase inversion method. This enabled the modification the active top layer of PES and PVDF thin film while maintaining the high mechanical strength offered by the NWFs. FTIR spectroscopy, sessile drop contact angle measurements, thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to study the membranes. The membrane flux and rejection were studied using the cross-flow membrane unit. The contact angle results revealed that the hydrophilicity of PES and PVDF membranes increased as the polyvinyl pyrrolidone (PVP) concentration was increased. TGA revealed that the PES and PVDF membranes were thermally stable up to 580ºC and 530ºC respectively. The cross-sectional SEM revealed that membrane pores become enlarged when PVP has been added. AFM showed that membrane roughness improved when PVP was added. A rejection of 98% humic acid was obtained for PES membranes supported on NWF1, compared to 94 % and 96 % for membranes supported on NWF2 and NWF3 respectively. The highest rejection of humic acid (HA) recorded for PVDF membranes supported on NWF1 was found to be 97 % compared to the 95% for membranes supported on NWF2 and NWF3 fabrics respectively. PES membranes supported on NWF2 exhibited low but best As(III) metal ions rejections whilst PVDF membranes supported on NWF3 exhibited low but best rejections for Cr(III) metal ions.

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

The main objective of this study is to analyze the demand for water in Denton. The data used for the study are obtained from the City of Denton Utilities Department, the Tax Appraisal District and government documents. The 121 households which have perfect ten years historical data of water consumption were selected to be the representatives of all households in Denton. The study reveals that the change in water consumption significantly relates to the change in marginal price. Furthermore, the weather variables also have strong effects on the water consumption, especially during summer. The coefficients of income and a "difference" variable are found to have the opposite sign but are not equal in magnitude. In fact, they should be equal in magnitude, but opposite in sign. While the estimated coefficients on all independent variables were highly significant statistically, the resulting coefficient on the house size variable was statistically insignificant in the model test. The results show that the difference variable is required in the model. It also had some effect on the water consumption. It is found that there is a small change in water consumption when the lot size is increased.

In the theoretical part, I mentioned the project management of buildings and the construction of prices in construction. In the next section I have described the building site and its water supply requirements. Finally, I have dealt with the cost of water and its consumption. The aim of the thesis was to analyze the influence of water prices on the cost of construction. I transferred this analysis to the model building in the practical part of the thesis. I determined the water consumption during construction, and then I analyzed the impact of the change in water prices on the construction cost.

Water scarcity has caused severe impact on the entire ecosphere while the climate change is resulting in high frequency of extreme weather conditions, especially extended period of drought. Due to the even increasing world’s population and the continued societal modernization, water scarcity is now one of the leading global challenges towards the development of human society. On the other hand, atmospheric water, accounting for 6 times the water in all rivers on Earth, is emerging as an alternative water resource. This dissertation thoroughly investigated the fully solar energy driven atmospheric water harvesting (AWH) process in a broad scientific and application context. The light-to-heat conversion process of solar photothermal materials was investigated first with a rationally designed droplet-laser system, which in combination with the calculation of heat of absorption of water vapor for various application scenarios, formed a theoretical basis of this dissertation research. As a result, a series of commonly used hydrated salts and their anhydrous counterparts were judiciously selected and successfully proven to be low-cost AWH materials to generate clean fresh water for arid regions. A hydrogel-deliquescent salt composite was further developed as AWH material with a significantly enhanced fresh water production capacity. A new design of nano-capsule encapsulated deliquescent salt was further put forward to enhance water vapor sorption/desorption kinetics, which enabled, for the first time, multiple sorption/desorption cycles within one day and thus multiplied water production capacity. The first-ever continuous AWH device, as opposed to batch-type one, was rationally designed, fabricated, and successfully tested in field conditions outdoors. At last, the dissertation pioneered a novel concept of atmospheric water sorption and desorption cycle for photovoltaic (PV) panel cooling. This dissertation shines significant light on sorption based atmospheric water harvesting and inspires more research efforts on this important research topic.

A sample of the surface-well water was taken from an area of the predominating soil of each of the three geological regions of Denton County, Texas, and a chemical analysis of each sample was made. This thesis deals with the area from which the samples were taken, the methods of analysis used, and the results of the analysis.

Public water supplies contain disease-causing microorganisms in the water or distribution ducts. In order to kill off these pathogens, a disinfectant, such as chlorine, is added to the water. Chlorine is the most widely used disinfectant in all U.S. water treatment facilities. Chlorine is known to be one of the most powerful disinfectants to restrict harmful pathogens from reaching the consumer. In the interest of obtaining a better understanding of what variables affect the levels of chlorine in the water, this thesis will analyze a particular set of water samples randomly collected from locations in Orange County, Florida. Thirty water samples will be collected and have their chlorine level, temperature, and pH recorded. A linear regression analysis will be performed on the data collected with several qualitative and quantitative variables. Water storage time, temperature, time of day, location, pH, and dissolved oxygen level will be the independent variables collected from each water sample. All data collected will be analyzed through various Statistical Analysis System (SAS®) procedures. Partial residual plots will be used to determine possible relationships between the chlorine level and the independent variables and stepwise selection to eliminate possible insignificant predictors. From there, several possible models for the data will be selected. F tests will be conducted to determine which of the models appears to be the most useful. All tests will include hypotheses, test statistics, p values, and conclusions. There will also be an analysis of the residual plot, jackknife residuals, leverage values, Cook’s D, press statistic, and normal probability plot of the residuals. Possible outliers will be investigated and the critical values for flagged observations will be stated along with what problems the flagged values indicate.

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