Advances in mathematical modelling and the availability of high speed computers with considerable memory size is making it possible to study the hydraulics of border irrigation in a greater depth than every before. A zero inertia mathematical model was found to be reliable and inexpensive among the models available in border irrigation hydraulics and was used for this study to simulate free outflow flowing border irrigation. Special emphasis was given to the runoff produced from such a system. This study dealt particularly with, the identification of pertinent open channel variables affecting runoff in border irrigation, presentation of predictive graphical and mathematical solution to quantify runoff, and with utilization of these solutions in developing reuse system design criteria. Inflow rate, surface resistance, border slope, soil infiltration characteristics, application time (time of cutoff and length of run of the border) were among other variables studied. As one might expect, runoff was found to increase with slope, flow rate, application time and decrease with increase in infiltration rate, length of run and bed and vegetation drag. Considering the number of variables affecting runoff characteristics from a given irrigation, it was obvious to see a thorough examination of each variable in dimensional terms was practically impossible. Also, presentation of the results would have required too many graphs. Dimensional anslysis was used to solve this problem and in developing dimensionless runoff curves. The ability to quantify runoff made it possible to develop reuse system design formula for proper sizing of reuse systems under several operational requirements. Shape function for the ultimate infiltrated depth profile was used to get times of runoff and also calculate various efficiencies which are useful for evaluating the system. The study shows, through the use of reuse system, the potential application efficiency can be changed from present values of 60 percent to 90 percent in Arizona. It also can be used to demonstrate the saving in energy that can be realized through such system. Step by step procedures for the design of reuse system using graphical and mathematical solutions are presented with a sample problem worked out. It is expected that the result of this study can be used by designers as well as operators of border irrigation systems without any difficulty with the aid of a simple pocket calculator. Other uses of the study include getting optimal design for the system itself by evaluating various possible designs and classroom instruction on the application of dimensional analysis to open channel hydraulics problems and design of reuse systems.

With the population of urban areas rapidly increasing, a much greater demand is being placed on existing water supplies. The arid southwestern region of the United States, in particular, is experiencing large population increases while possessing limited water resources. Tucson is a representative city in the region facing problems of providing an adequate water supply to the public in the future. Presently, Tucson is being supplied entirely with groundwater. Increases in population and industrial activities, however, have caused a steady decline of the groundwater table in the Tucson Basin. The reclamation of wastewater and the importation of water have been studied as alternatives in alleviating the annual decline of the groundwater table. Problems still exist, however, preventing the immediate use of both aforementioned supplies of water. In developing the water resources of an area, every possible source of water must be evaluated. A source which has not received much attention, but which merits much attention, is the water occurring as urban runoff following intense storms. In order to evaluate the potential of urban runoff as a water supply, the study includes investigations of water quality, water treatment through storage and coagulation, and problems involved with the utilization of storm water. Samples of runoff from three diversified urban watersheds in the Tucson area were analyzed for bacterial, mineral, pesticide, solids, and chemical oxygen demand concentrations. The watersheds were characterized according to the percentage of the total area devoted to a particular land use. In addition, the hydrologic characteristics of each storm were tabulated. Correlation coefficients were determined between the quality parameters and the watershed and hydrological characteristics. Development of regression equations equating quality parameters as a function of both watershed and hydrological characteristics was also undertaken. The final analysis of the quality study involved the determination of relationships between quality parameters of chemical oxygen demand, total coliforms and suspended solids and the point of time on the hydrograph at which runoff was sampled. Prior to beneficial use of the urban runoff, treatment to varying degrees will be required. In the second phase of this study, the efficiency of treatment by the simple methods of storage and alum coagulations was studied. Five gallon samples were collected from randomly selected storms and used either in the storage or coagulation study. Changes in chemical oxygen demand, solids and bacterial concentrations were evaluated at selected intervals during storage for a period of a week. Jar test studies utilizing varying doses of alum were undertaken on water collected from each of the watersheds, determining the efficiency of chemical oxygen demand, turbidity, and total coliform removals. The final phase of the study involved discussion of the problems attendant with the planning and design of treatment facilities. Included in this phase were sections involving water quality standards and the related treatment processes, waste sludge production and treatment methods, and costs pertaining to treatment. Legal aspects of appropriating the urban runoff were considered and the possible conflicts between upstream and downstream interests noted. The study concluded with a demonstration of the application of dynamic programming for optimally planning the location and capacity of storage treatment facilities at urban sites.

With groundwater resources becoming less available in the physical, economic, and legal senses, water reuse is rapidly gaining momentum in the arid West. An institutional assessment of water reuse in the Tucson Basin in Arizona indicates that despite institutional changes encouraging the substitution of effluent for native groundwater, many opportunities for water reuse are precluded by existing water rights arrangements and insufficient economic incentives. An economic assessment compares potential benefits and costs of implementing water reuse plans for the Tucson area with potential benefits and costs of alternative water-supply scenarios in which similar quantities of water are provided from other sources. Alternative water sources include pumping native groundwater, "reallocating" water saved through reduction in low value water uses, and importing surface water and groundwater from other basins. The results of this study indicate that at the present time, there is no convincing economic justification for increasing water reuse as planned by the City of Tucson. Not only are reduction in use and importation alternatives less costly to implement than increasing effluent use, they also save more groundwater. The results of the economic assessment indicate that the citizenry of the Tucson Basin would be better served if planned increases in the use of effluent in the Tucson metropolitan area were postponed until the costs become more competitive with the costs of alternatives.

The objective of this investigation was to utilise water pinch analysis as a tool for the optimisation of fresh water use in an integrated pulp and paper mill. The investigation was carried out at Mondi Paper in Merebank, south of Durban. The pulp and paper manufacturing process is a large consumer of fresh water and minimising the amount of fresh water used in the processes is beneficial from both a cost and environmental point of view. There are examples of mills which have "closed" their water systems to the extent that fresh water make up is minimal and most of the water is recycled and reused in a closed loop. These examples provide guidance on the basis of proven methods for reducing water consumption in the pulp and paper industry and can be used as a reference for mills wishing to reduce water consumption by making use of tried and tested methods. This investigation sought to provide an alternative method to identifying potential savings in fresh water consumption by making use of water pinch analysis. This was done at Mondi Paper by analysing individual parts of the mill and then a larger section of the mill which included both pulp and paper production. Flow rates of water streams and fibre content in those streams were obtained from plant data, where available, and this data was used to produce.a mass balance using the Linnhoff-March software, Water Tracker. The balance produced using Water Tracker provided the missing flow and fibre content data and this data was used as the input for the Linnhoff-March software, Water Pinch , to perform the water pinch analysis. The results achieved when analysing the individual parts of the mill did not demonstrate potential for significant savings in fresh water consumption, however the analysis of the integrated section of the mill identified a potential reduction in fresh water. It was found that the application of a single contaminant analysis to the larger section of the mill identified a possible reduction in the freshwater requirement of 8.1% and a reduction in effluent generated of 5.4%. This is a savings of R1 548 593 per annum based on 2003 costs of fresh water and effluent disposal. This analysis was conducted using the most simplified representation possible to produce meaningful results in order to evaluate the effectiveness of water pinch analysis in optimising the fresh water consumption in an integrated pulp and paper mill. It is demonstrated that water pinch analysis is potentially a useful tool in determining the minimum fresh water requirement of a site. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.

This study focused on the investigation of the impact of household cleaning and personal care products on the quality of grey water and the assessment and optimisation of grey water treatment by a novel constructed wetland design. The prototype wetland design which comprised three-stage cascading beds (0.27 m 2 by 0.20 m deep) with sand media, (d10: 1.0 mm and d90: 4.0 mm) was tested for treatment performance to meet non-potable reuse standards in three versions, unplanted open beds, unplanted covered beds, and planted beds (comprising mixtures of Iris pseudacorus, Iris chrysographes, Carex elata Aurea and Mentha aquatica). The prototypes were benchmarked against a standard single-pass wetland (6 m 2 by 0.7 m) planted with Phragmites australis. Performance was measured in terms of removal of conventional water quality determinant parameters, as well as Total coliforms and E coli, and surfactants. Microbial dynamics were also monitored during the study by looking at variations in microbial compositions with time for the different wetlands. All the wetland versions effectively removed more than 98 % turbidity and organics meeting the most stringent reuse wastewater reuse standards of < 2.0 NTU and < 10 mg BOD5/L respectively. The influent grey water had low BOD:COD ratio ranging from 0.27 – 0.45, which is indicative of low biodegradability. The comparison of the cascade wetland performances showed the following: open beds > planted = covered, with the open beds version meeting reuse standards virtually throughout the monitoring period, despite recurrence of schmutsdecke in the top bed. All wetland technologies supported viable populations of microorganisms. Only phospholipid fatty acids (PLFAs) of lower carbon chain length (< C20) had concentrations greater than 1 mol %, in all the wetlands beds, confirming that the majority of the PLFAs in the media were from contribution of microbial organisms and not plant organic matter. Characterisation of microbial organisms was carried out to understand the constructed wetlands functioning and thus the treatment processes. The household products showed nutrient deficiency signifying low treatability. Product branding did not show correlation with any water quality parameters. In terms of toxicity, laundry and cleaning products were more inhibiting to soil microorganisms than were personal care products.

Realized and potential threats of water scarcity due in part to global climate change have increased the interest in potable reuse of municipal wastewater. Recalcitrant trace organic compounds (TOrCs), including pharmaceuticals, steroid hormones and industrial compounds in wastewater are often not efficiently removed by conventional wastewater treatment processes, thereby ubiquitously occurs in natural and wastewater effluents. Advanced water treatment processes including advanced oxidation processes (AOPs), activated carbon adsorption and membrane separation processes have been demonstrated to efficaciously attenuate many classes of TOrCs. In this dissertation, attenuation of TOrCs by ozone oxidation, powdered activated carbon (PAC) and nanofiltration membrane and their monitoring strategies were demonstrated in water reuse applications. Particularly, the first main chapter attempted to elucidate the use of indicator/surrogate for predicting TOrC attenuation by ozone oxidation in a theoretical basis. A semi-empirical model was developed, which successfully predicted many TOrCs with various oxidation kinetics simultaneously. The following chapter was pertaining to development of exploratory models to predict TOrC abatement by ozone. It was concluded that principal component (PC) analysis in conjunction with artificial neural network (ANN) resulted in precise and robust prediction of TOrC attenuation. In addition to oxidation process, kinetic of TOrC adsorption by PAC was scrutinized subsequently. It was found that the initial-phase adsorption was controlled by surface reaction due to hydrophobic interaction. In addition, correlation between surrogate reduction and TOrC attenuation was independent upon water quality at the early phase of adsorption, which was explained theoretically. In the last chapter, synergistic effects of NF membrane in conjunction with pre-ozonation was investigated for TOrC abatement in brine. As a result, all the tested TOrCs were efficaciously attenuated and not quantifiable due to their concentration below limit of quantification. In addition, ozonation also alleviated organic fouling potential substantially.

Thesis (MTech (Agriculture))--Cape Peninsula University of Technology. / During the past years government regulations concerning winery effluent became stricter to protect the environment. Wineries are continually improving wastewater management and finding appropriate ways to reduce cellar effluent. Due to water scarcity in South Africa, it could be a huge advantage if winery effluent could be used as irrigation water for vineyards. If the industry can re-use the untreated wastewater, it will not only save a huge amount of irrigation water, but it will also be able to get rid of the vast amount of cellar effluent. Grape production plays a major role in agriculture worldwide. The world production of grapes worldwide in 2013 was 751 MgL. South Africa is the 9th biggest wine producer in the world with 10 X 10HL of wine. In the earlier years of wine production in South Africa, the small volumes of winery wastewater did not have a negative impact on the environment but with the increased volumes over the last years, the possibility of contamination of the soil and the environment has increased. Government decided to regulate the irrigation of cellar effluent with the National Water Act of 1998 as approved by the Department of Water Affairs (DWAF). There are different ways to get rid of cellar effluent. One successful way is by constructed wetlands where plants are used to break down minerals which could be detrimental to the environment. This is a successful way to get rid of cellar effluent but could take up to six weeks before the mineral contents can be broken down by the plants. Another way is to use bio-reactors to break down the contents of the cellar effluent, but this is expensive. Wastewater consists of important nutrients needed for plant growth such as macro-nutrients like N, P, K and micro-nutrients like Fe, Zn, Mn and Cu and a substantial amount of organic matter. If cellar water, just like domestic wastewater is used for irrigation the farmer can save water when he uses less fertiliser, because of the high nutrient content in the cellar effluent. If cover crops such as oats (Avena sativa L. cv. Pallinup) in winter and pearl millet (Pennisetum glaucum (L.) R. Br.) in summer can be used to remove excess cations, as well as unwanted chemicals such as toxic metals from the soil, it may result in effluent water with a higher chemical oxygen demand (COD) level than the current legal limitations that can be used to irrigate the vineyard. The aim of this project was, therefore, to determine the ability of oat and pearl millet cover crop to remove excess minerals from the soil irrigated with augmented water at different COD levels, without a negative effect on growth and yield of the vineyard or wine quality. Field trials were carried out in a Cabernet Sauvignon/99 Richter vineyard established on a sandy soil at the Goudini Cellar near Rawsonville.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Science. April, 2015 / Microbial fuel cell (MFC) technology presents great potential for use as a dual system for industrial waste water remediation and electricity generation. The hurdle in up-scaling this technology has been identified as MFC-bioreactor architecture, both with regards to bioremediation and carbon source to electricity conversion rates. In addition to the latter’s limitations, the use of expensive mediators and membrane to enhance MFC performance renders the technology uneconomic to employ industrially. A 60mm high double chamber membrane and mediator-less MFC-bioreactor was designed, and constructed. The novel MFC-bioreactor made of transparent polyacrylic plastic had a total working volume of 8 litres with the anode chamber situated at the bottom and the cathode chamber at the top separated by a 10cm deep artificial membrane made up of glass wool, glass beads and marble balls. The MFC was operated under various operating parameters including; feeding modes (batch and continuous), with different substrate concentration at a range of external resistance (100-9000Ω) .The voltage produced during MFC operation was monitored and used to estimate the power density output of the MFC. The pseudo membrane was able to sufficiently separate the anode and cathode chambers allowing the development of potential difference and hence generation of current. The MFC demonstrated the potential for sustainable operation by producing and maintaining a stable power density of 2000mW/m2 when operated with an external resistance of 1000Ω. This power density was accompanied by a 73% remediation efficiency of the synthetic wastewater. It was concluded that the results of this research show proof of concept for a membrane-less MFC that can produce electrical energy in the absence of an electron shuffling mediator.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2015 / The scarcity of water and strict environmental regulations have made sustainable engineering a prime concern in the process and manufacturing industries. Water minimisation involves the reduction of freshwater use and effluent discharge in chemical plants. This is achieved through water reuse, water recycle and water regeneration. Optimisation of the water network (WN) superstructure considers all possible interconnections between water sources, water sinks and regenerator units (membrane systems). In most published works, membrane systems have been represented using the “black-box” approach, which uses a simplified linear model to represent the membrane systems. This approach does not give an accurate representation of the energy consumption and associated costs of the membrane systems. The work presented in this dissertation therefore looks at the incorporation of a detailed reverse osmosis network (RON) superstructure within a water network superstructure in order to simultaneously minimise water, energy, operating and capital costs. The WN consists of water sources, water sinks and reverse osmosis (RO) units for the partial treatment of the contaminated water. An overall mixed-integer nonlinear programming (MINLP) framework is developed, that simultaneously evaluates both water recycle/reuse and regeneration reuse/recycle opportunities. The solution obtained from optimisation provides the optimal connections between various units in the network arrangement, size and number of RO units, booster pumps as well as energy recovery turbines. The work looks at four cases in order to highlight the importance of including a detailed regeneration network within the water network instead of the traditional “black-box’’ model. The importance of using a variable removal ratio in the model is also highlighted by applying the work to a literature case study, which leads to a 28% reduction in freshwater consumption and 80% reduction in wastewater generation. / GR2016

A research project report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering (Civil Engineering). Vanderbijlpark, 2016 / South Africa is a semi-arid country with an average rainfall of 450 mm per annum. According to the Department of Water Affairs, the total registered water usage in 2013 met the estimated 2025 high water requirement of 17.3 billion m3/annum. Therefore, the need had arisen to reduce water consumption and increase water supply to ensure the sustainability of our nation’s water resources. Many studies show that wastewater reuse or water reclamation is an under-utilized and very viable water conservation concept in South Africa. The reuse of wastewater for direct potable or direct non-potable reuse is a highly debated topic requiring frequent engagement and investigation. Although direct reuse for potable uses is often more contentious than direct reuse for non-potable uses, it is worth investigating for possible future implementation at certain water scares areas. Hence, this study investigated the possibility of the future implementation of direct wastewater reuse at Hartbeesfontein - a selected South African community, for potable or non-potable use. The study incorporated potential users’ perceptions, the cost implications of reuse and water saving potential by means of different water balance models. The survey conducted, measuring the intention of the residents from Hartbeesfontein to accept direct wastewater reuse for potable and non-potable use, revealed the community’s overwhelming acceptance (about 70%) of a reuse system should it be implemented in the future. The community’s preference for wastewater reuse for non-potable use (75%) was higher than for potable use (67%). Hypothetically, it would be possible to reuse 85% of the community’s daily demand for potable use, if all the wastewater collected at the wastewater treatment plant could be treated. It would then mean that the municipality will only need to provide 15% of the daily water demand. The option to reuse wastewater for non-potable use (i.e. to supply an industry) could save the community 22% its daily water demand. In this study, the cost of wastewater treatment for potable use was approximately 350% higher than the cost of potable water supplied by the Midvaal Water Company. The cost of treating wastewater for non-potable use however was approximately 46% less than the cost of potable water supplied by the Midvaal Water Company. By incorporating the outcomes of the water balance, perceptions of the community and analysis of the different wastewater reuse scenario costs, it was evident from the study that direct wastewater reuse for non-potable industrial application was the most viable water reuse option for Hartbeesfontein. / MT2017