This thesis contains the results and discussion of an exploratory investigation into the application of Crossflow Microfiltration (CFMF) for solid/liquid separation in biological wastewater treatment systems. The principal objective of the study was to assess the influence of CFMF on the performance of identified biological wastewater treatment systems. It was not the objective to optimise filtration performance. A literature review indicated that the crossflow mode of filtration has been widely accepted as a unit operation in the fermentation industry. The filtration mode is now being applied not only for solid/liquid separation but also for separations on a molecular and ionic level. Very few applications of crossflow filtration in the context of biological wastewater treatment solid/liquid separation are reported in the literature. The reasons for this limited experience would appear to be the scale involved and the perceived high costs; separations in the fermentation industry are usually conducted at relatively small scale (laboratory or pilot-scale) and involve high-value products, justifying high capital and operating costs. Also, the high level of separation performance attained is perhaps not necessary for many wastewater treatment applications. No doubt these reservations are largely valid. However, these arguments cannot be applied equally to all filtration methods and wastewater treatment schemes. For example, the costs of microfiltration are substantially less than ultrafiltration or reverse osmosis, and in certain cases effluents with extremely low suspended solids contents may be required. In the light of these observations an investigation of CFMF for solid/liquid separation in biological wastewater treatment systems appears justified. Two biological treatment systems were selected for study: the Upflow Anaerobic Sludge Bed (UASB) reactor and the Activated Sludge system. The envisaged benefits accruing from the application of CFMF were different in each case.

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A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Masters of Science in Engineering, 2019 / Water is the basic necessity for all living organisms. About, five million people specifically children are dying each year due to dehydration or use of toxin infected water around the world. In South Africa approximately seventeen percent of the population do not have access to safe drinking water. Considering all of these challenges it is evident that monitoring the quality of water is important for providing safe and clean water. Several researchers have shown that the parameters related to the quality of drinking water can be monitored effectively in the field. To accurately determine the quality of water it needs to be tested for many parameters. Measuring all possible parameters can be a daunting task. It is very costly and time consuming at the same time. There is also research available in which researchers have proposed remote monitoring of water quality based on fewer parameters in a given water sample to conclude whether or not the given sample was safe for drinking. This has met with limited success. There is however very limited or no scientific evidence available to validate the effectiveness of the selected fewer parameters to determine the quality of drinking water. The research presented in this dissertation proposes a list of fewer parameters that are monitored to determine the quality of water. The effectiveness of those parameters in determining the quality of drinking water has been verified by conducting a detailed analysis on a number of water samples in a laboratory environment. The research has also proposed a system that is capable of monitoring those parameters remotely. This enables the water supplying authorities to determine the basic quality of water without testing it in the laboratory environment resulting in a decreased time and lower cost. / TL (2020)

During the construction of a chemical processing plant, a polyphosphate product was selected for use as a corrosion inhibitor in the open recirculating cooling tower system. After several months of operation, problems in the system made evident the fact that polyphosphate as a corrosion inhibitor was not acceptable. An organic corrosion inhibitor was substituted for the phosphate, resulting in improved corrosion protection and the elimination of phosphate fouling.

The wastewater from the electroplating processes required for the production of printed circuit boards has a high heavy metal content. The regulatory agencies of both the Federal Government and the State of Florida set pretreatment limitations on the quantity of the hazardous heavy metal ions that may be discharged t o a receiving body of water or to a Publicly Owned Treatment Works. A number of treatment processes are available for the effective removal of these pollutants. The mechanism behind the more common processes are discussed in this paper. Many variables must be considered in the design of a wastewater pretreatment system. The more important variables are enumerated and the criteria to integrate these variables into the treatment selection process and ultimately into the design of the pretreatment system are covered in detail. Flow diagrams and equipment lists for the treatment processes selected are given as well as a breakdown of the total construction costs for this project.

The disposal of water treatment residual has received little attention due to a lack of regulation, funding, and concern about their environmental impacts. Many treatment plants discharge alum residual directly into nearby water courses or dewater them for landfilling. If suitable land is available, land application of residual is cost effective and has the potential for negligible effects on the environment and may prove to be a long-term solution to the disposal problem. This research project investigated the effects of land application of alum residual on crops or vegetation grown on fine loamy Slagle soil (<i>siliceous, thermic aquic hapludults</i>). Prior research identified the reduction in plant available P as a potential concern. During summer months. many water treatment plants also add powdered activated carbon (PAC) during the treatment process to prevent taste and odor problems. The PAC ultimately ends up in the residual and alters its chemical characteristics. The effects of land-applied PAC residual on plant growth was also investigated. Fescue (<i>festuca arundinacae</i>) yields decreased with increased residual addition. Lime addition did not Significantly effect fescue yield. Reductions in plant yield were attributed to a reduction in plant available phosphorus (P) in soils receiving higher residual loadings. Supplemental fertilization was able to overcome the P availability problem. The presence of manganese in the residual did not adversely affect plant yields. Likewise, incorporation of spent PAC into the residual did not reduce yields. / Master of Science

The management of hypersaline brines is a topic of growing environmental concern. While desalination is an increasingly attractive treatment option, conventional desalination technologies face technical limitations in high-salinity environments. This dissertation guides scientific development in the field of hypersaline desalination and advances our fundamental understanding of the novel technology Temperature Swing Solvent Extraction (TSSE). Chapter 1 motivates the environmental, regulatory, economic, and water scarcity drivers for hypersaline desalination and briefly outlines the objectives and contributions of the thesis. In Chapter 2, the sources and characteristics of hypersaline streams are introduced, and a primer on the energy requirements of high-salinity desalination is presented. The prospects and challenges of emerging technologies for hypersaline desalination are critically reviewed along the dimensions of energy consumption, fit- for-purpose compatibility, and ability to precipitate salts in the bulk solution. TSSE, which utilizes a switchable solvent with thermally responsive polarity to extract and subsequently release water from hypersaline feeds, shows particular promise in this field. Chapter 3 of this dissertation investigates the influence of temperature on the equilibrium partitioning of water, salt, and solvent in biphasic TSSE mixtures. Analysis reveals that TSSE hypersaline desalination performance is inherently constrained by a productivity-selectivity tradeoff: as the operating temperature is tuned to improve water extraction, salt rejection worsens. In Chapter 4, a novel configuration of TSSE with intermediate-step release (TSSE-IR) is introduced, and its desalination performance is assessed. The intermediate temperature step is demonstrated to dramatically improve salt rejection compared to the conventional single-step operation while minimizing sacrifices in water recovery yields. Chapter 5 of the dissertation advances a physical chemistry framework for the a priori prediction of activity coefficients in TSSE biphasic systems. Water partitioning behavior is shown to be enthalpically driven, and salt partitioning behavior is determined to be primarily influenced by the anion. In Chapter 6, the distribution behaviors of organic contaminants, which are present in real hypersaline brines, are measured in TSSE biphasic mixtures. The fate of these compounds can be reliably predicted from the physicochemical properties of octanol-water partition coefficients and acid-base dissociation constants. Finally, Chapter 7 details the contributions and implications of the dissertation, offering suggestions for targeted areas of future research. Overall, this work helps to advance the development of cost-effective and energy-efficient desalination of high-salinity streams to enable a circular water economy.

Submitted in fulfilment of the requirements of the Degree of Master of Technology: Chemical Engineering, Durban University of Technology, 2013. / Lack of access to clean and safe potable water, especially for people living in rural areas of developing economies, is a matter of great concern in different parts of the world. Measures taken to address the challenges arising from this problem include the improvement of existing water purification methods and development of new appropriate technologies such as point of use (POU) water treatment technologies. One such appropriate POU technology is the Remote Rural Water Treatment System (RRWTS) developed at Durban University of Technology (DUT) in South Africa. The RRWTS is based on polyester woven fabric microfiltration (WFMF) membranes and other locally sourced materials. The filtration unit consists of flat sheet modules assembled into a pack and permeate outlets connected to a manifold and then to a tap. The system is gravity driven and therefore eliminates the use of pumps and electricity. This system has shown potential for use in water treatment as it produces permeate with turbidity below 1 NTU, has a high permeate flow rate, and is easy to use and maintain. However, the major challenge facing its use is that permeate does not meet the set microbiological standards for drinking water (zero E. coli in 100 mL treated water). The RRWTS can ideally remove 95 to 99 per cent of the influent E. coli. This necessitates the use of a separate disinfection step, often using chlorine for complete removal of microbial contaminants. The objectives of this study were: to investigate the incorporation of silver nanoparticles (AgNPs) into the WFMF membrane; to evaluate the disinfection efficacy of the AgNPs impregnated filter (coated filter); and to determine the long term performance of the coated filter in terms of disinfection and silver elution (90 days). The study was conducted in four stages. Firstly, AgNPs were incorporated on the membrane using in situ chemical reduction of silver nitrate using sodium borohydride. Secondly, the filters were characterized using scanning electron microscopy (SEM) to determine the morphology, and the Sessile drop method for contact angle measurement was employed to determine the membrane hydrophilicity. In addition, X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) spectroscopy and UV- Visible Spectroscopy iii were used to investigate the presence of AgNPs on the coated filter. Thereafter, the antibacterial efficacy of the filters was evaluated using a laboratory scale experimental rig and different microbial assays. Raw river water and deionized water spiked with E.coli (synthetic feed) were used as feed. Lastly, the effects of concentration of E.coli in the feed and silver elution on the disinfection performance of the coated filter over time were investigated. The performance criteria were based on permeate quality and they included: turbidity, concentration of E.coli, and silver concentration. The characterization results depicted that AgNPs were successfully immobilized on the WFMF membranes by in situ chemical reduction. The incorporation of AgNPs was ascertained using UV-Vis Spectrophotometry, FT-IR and XRD. The Sessile drop test indicated that the membrane became more hydrophilic (77 per cent decrease in water contact angle) and the permeability increased significantly as a result of the coating (p <0.05). The coated filters demonstrated excellent filtration performance producing permeate with turbidity less than 1 NTU for feed turbidities between 40 and 700 NTU. The disinfection efficacy was found to be excellent, producing permeate with zero E.coli concentration for feed concentrations between 10,000 CFU/ 100 mL and 85,000 CFU/100 mL. The E.coli removal efficiency was 100 per cent for a period of 63 days of continuous filtration. The ICP Atomic Emission Spectrometer (ICP-AES) results showed that the leaching of silver from the coated filters over time (90 days) was always below 0.1 mg/L which is the widely accepted guideline for potable water. From the literature surveyed, this is the first study which investigated the use of AgNPs in WFMF membranes for potable water disinfection. The coated filters treated water to the set international standards for potable water in terms of physical and microbiological quality. However, the study did not comprise investigation into the effect of different silver loadings on the filter performance. The study also employed E.coli as the indicator organism for faecal contamination. The results obtained can be used as a model for future work using other microorganisms and different silver loadings in order to compare the performance.

Submitted in fulfillment for the requirements of the degree of Master of Technology: Chemical Engineering,Durban University of Technology. Durban. South Africa, 2015. / Access to safe drinking water supply is still a major problem especially in remote rural areas of developing countries. These communities rely solely on untreated surface and ground waters for survival due to the lack of financial resources to provide access to piped water. The consumption of this water in turn makes them easily susceptible to water related diseases. Hence, there is a need for an interim solution while the government is still sourcing funds for the distribution of water to these communities. Membrane filtration is a promising technology for the treatment of surface water as it does not alter the taste or smell of the end product. The main limitation for the implementation of membrane technology in rural areas is still energy demand, fouling and the skills required for membrane cleaning. Biological ultrafiltration is an emerging technology that produces water of high quality in terms of turbidity, organics and bacteria removal. The technology has been evaluated using a gravity driven dead-end mode on European waters and it offered acceptable stabilisation of fluxes for extended periods without any chemical cleaning or backwashing. This is a promising technology which can be implemented to act as an interim solution for the treatment of surface water in remote rural areas prior to consumption. This study concerns the evaluation of a biological ultrafiltration membrane system on local three South African rivers, namely, Tugela River, Umbilo River and Umgeni River. A laboratory systems comprising of a feed tank and six membrane modules connected in parallel was set up to assess the performance of a bio-UF membrane on a range of surface waters. The performance was assessed on the system’s ability to produce stable fluxes from the three rivers, the system ability to produce water with acceptable quality in terms of SANS 241:2011 for turbidity, TOC, total coliforms and E-coli. The membranes were initial cleaned and the flux rates for ultra-pure water were determined for each membrane prior to being exposed to raw water. Raw water samples were collected from three rivers with varying turbidity, total coliforms and organics. The concentrations of these contaminants were tested prior to running the raw water through the system. Thereafter, permeate was collected with time and its quality was evaluated in terms of turbidity, TOC and coliforms. The impacts of algae on flux stabilisation were evaluated by allowing the bio-UF system to run for a minimum of 3 months with and without algae growth. The system was found to be able to produce water that is compliant with the SANS 241:2011 standard in terms of turbidity, total coliforms, E-coli and TOC concentration. The system was also found to be unable to produce stable fluxes for all three rivers. The observed responses were noted to be similar to normal dead-end response, however, a slow declining flux rates was observed for Umgeni River. The presence of algae during the operation was a bio-UF membrane system was noted to further decrease the rate of flux decline. There appears to be a correlation between the raw water quality and the rate of flux decline. A further investigation was carried out aimed at assessing the relationship between the concentration of bacterial counts, TOC and turbidity. From the obtained results, it was noted that feed water with low turbidity (≤ 5 NTU), high bacterial count (≥30 000) and high total organic carbon (≥70 mg/L) is able to reduce the rate of flux decline. Hence, it can be concluded that a dead-end gravity driven Bio-UF membrane system can be used for the treatment of surface water in remote where the most main contaminants are from natural organic matter, micro-organisms and turbidity. Furthermore, it is able to produce slower declining flux rates which will increase the filter run time. It is recommended that the impacts of algae, type of bacteria and organics that enable slow decline in flux rates during the operation of Bio-UF should be investigated in order to identify means of enhancing the flux rates. Microfiltration membranes are available on the local markets hence it is also recommended that the performance of Bio-UF should be evaluated in comparison to Bio-MF.

In potable water preparation, chlorination is the last step before the potable water enters the distribution network. Umgeni Water Wiggins Waterworks feeds the Southern areas of Durban. A reservoir at this facility holds treated water before it enters the distribution network. To ensure an adequate disinfection potential within the network, the free chlorine concentration in the water leaving the reservoir at the Umgeni Water Wiggins Waterworks should be between 0.8 and 1.2 mg/L. The aim of this study was to develop an effective strategy to predict and control the chlorine concentration at the exit of the reservoir. This control problem is made difficult by the wide variations in flow and level in the reservoirs, together with reactive decay of the chlorine concentration. A Computational Fluid Dynamic study was undertaken to gain understanding of the physical processes operating in the reservoir (FLUENT software). As this kind of modelling is not yet applicable for real-time control, compartment models have been created to simulate the behaviour of the reservoir as closely as possible, using the results of the fluid dynamic simulation. These compartment models were initially used in an extended Kalman filter (MATLAB software). In a first step, they were used to estimate the kinetic factor for chlorine consumption and in a second step, they predicted the chlorine concentration at the outlet of the reservoir. The comparison between predictions and data, allowed the validation of the compartment models. A predictive control strategy was developed using a Dynamic Matrix Controller, and tested offline on the compartment models. The controller manipulated the chlorine concentration in the inlet of the reservoir in order to control the chlorine concentration in the outlet of the reservoir. Finally, the simplest compartment model was implemented on-line, using the Adroit SCADA system of the plant, in the form of a Kalman filter to estimate the chlorine decay constant, as well as a predictive model, using this continuously-updated decay parameter. The adaptive Dynamic Matrix Controller using this model was able to control the outlet chlorine concentration quite acceptably, and further improvements of the control performance are expected from ongoing tuning. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.