M. Tech. (Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / A novel technology in the treatment of river water, which involves an electrochemical treatment technique to produce domestic or drinking water is being investigated using aluminium and iron electrodes in an electrochemical circuit. Coagulation and flocculation are traditional methods for the treatment of polluted water. Electrocoagulation presents a robust novel and innovative alternative in which a sacrificial metal anode treats water electrochemically. This has the major advantage of providing mainly active cations required for coagulation and flocculation, without increasing the salinity of the water. Electrocoagulation is a complex process with a multitude of mechanisms operating synergistically to remove pollutants from the water. A wide variety of opinions exist in the literature for key mechanisms. A lack of a systematic approach has resulted in a myriad of designs for electrocoagulation reactors without due consideration of the complexity of the system. A systematic, holistic approach is required to understand electrocoagulation and its controlling parameters. An electrocoagulation-flotation process has been developed for water treatment. This involved an electrolytic reactor with aluminium and/or iron electrodes. The water to be treated (river water) was subjected to coagulation, by Al(III) and Fe(II) ions dissolved from the electrodes, resulting in floes floating after being captured by hydrogen gas bubbles generated at the cathode surfaces. Apparent current efficiencies for AI and Fe dissolution as aqueous Al(III) and Fe(II) species at pH 6.5 and 7.8 were greater than unity. This was due to additional chemical reactions occurring parallel with electrochemical AI and Fe dissolution: oxygen reduction at anodes and cathodes, and hydrogen evolution at cathodes, resulting in net (i.e. oxidation plus reduction) currents at both anodes and cathodes. Investigation results illustrate the feasibility of ferrous and aluminium ion electrochemical treatment as being a successful method of water treatment. Better results were achieved under conditions of relatively high raw water alkalinity, relatively low raw water turbidity, and when high mixing energy conditions were available.

A research 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 Masters of Science in Engineering, 2017 / Access to good quality drinking water is essential for the maintenance of public health. To guarantee a steady supply of good quality water, water treatments plants are designed to provide potable water that meets national and, where necessary, local water quality standards. While the protection of natural water resources against pollution, and proper treatment of water at treatment plants are both crucial to the provision of safe drinking water, the reality is that the quality of treated water can degrade during distribution. Microbial proliferation within distribution systems can cause problems such as unpleasant tastes and odours as well as the proliferation of pathogenic microorganisms. For most utilities, it is biofilm that grows on pipe surfaces that act as permanent inocula continuously inoculating the bulk water as it flows through the distribution system. Distribution system biofilm growth and the resulting impact on water quality can be minimized by various treatment processes, designed to remove biodegradable organic matter (BOM) from the water. The removal of BOM is of great importance to water utilities because it eliminates bacterial regrowth and the many associated water quality issues. Hence, the spatial and temporal mapping of biodegradable organic carbon (BDOC) offers water utilities an effective strategy in managing the BOM in the distribution system. This research is aimed at evaluating the applicability of BOM measurement protocols to monitoring biostability and biofilm formation potential within a drinking water distribution system (DWDS). This study specifically investigated the efficacy of a simplified version of the high-density BDOC test as a protocol for monitoring BDOC in finished water. The high-density BDOC protocol was found to be a more streamlined approach in contrast to the assimilable organic carbon (AOC), and provides a suitable monitoring mechanism for lowering biofilm formation potential in DWDSs. / CK2018

A study conducted by the World Health Organization and United Nations Children's Fund, concluded that approximately 768 million people worldwide are not receiving sanitary drinking water suitable for consumption. While there are many water treatment methods, lime softening proves to be one of the more effective approaches as it removes a wide variety of harmful compounds including arsenic, lead, mercury, and cadmium under the correct conditions. The greatest issues with lime softening on a smaller scale include the complexity of the chemistry and need for monitoring. By designing the system for groundwater sources and with a smaller capacity, this thesis hoped to reduce the level of monitoring, chemical expertise, and cost needed for operation. While promising results occurred in the removal of arsenic and total hardness, this project was unable to obtain consistent results and final water samples with pH values between the recommended standard of 6.5 to 8. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

Cheng Yee Wan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 95-112). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Table of Contents --- p.vi / List of Figures --- p.xi / List of Plates --- p.xiv / List of Tables --- p.xvi / Abbreviations --- p.xviii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Legionella pneumophila --- p.1 / Chapter 1.1.1 --- Bacterial morphology and ultrastructure --- p.2 / Chapter 1.1.2 --- Microbial ecology and natural habitats --- p.4 / Chapter 1.1.2.1 --- Association with amoeba --- p.5 / Chapter 1.1.2.2 --- Association with biofilm --- p.5 / Chapter 1.2 --- Legionnaires' disease and clinical significance --- p.6 / Chapter 1.2.1 --- Epidemiology --- p.6 / Chapter 1.2.1.1 --- Worldwide distribution --- p.6 / Chapter 1.2.1.2 --- Local situation --- p.7 / Chapter 1.2.2 --- Clinical presentation --- p.7 / Chapter 1.2.3 --- Route of infection and pathogenesis --- p.8 / Chapter 1.2.4 --- Diagnosis --- p.10 / Chapter 1.2.4.1 --- Culture of Legionella --- p.10 / Chapter 1.2.4.2 --- Direct fluorescent antibody (DFA) staining --- p.13 / Chapter 1.2.4.3 --- Serologic tests --- p.13 / Chapter 1.2.4.4 --- Urine antigen testing --- p.14 / Chapter 1.2.4.5 --- Detection of Legionella nucleic acid --- p.15 / Chapter 1.2.5 --- Risk factors --- p.15 / Chapter 1.2.6 --- Treatment for Legionella infection --- p.16 / Chapter 1.3 --- Detection of Legionella in environment --- p.16 / Chapter 1.4 --- Disinfection methods --- p.17 / Chapter 1.4.1 --- Physical methods --- p.19 / Chapter 1.4.1.1 --- Filtration --- p.19 / Chapter 1.4.1.2 --- UV-C irradiation --- p.20 / Chapter 1.4.1.3 --- Thermal eradication (superheat-and-flush) --- p.21 / Chapter 1.4.2 --- Chemical methods --- p.21 / Chapter 1.4.2.1 --- Chlorination --- p.21 / Chapter 1.4.2.2 --- Copper-silver ionization --- p.22 / Chapter 1.4.3 --- Effect of biofilm and other factors on disinfection --- p.23 / Chapter 1.5 --- Photocatalytic oxidation (PCO) --- p.24 / Chapter 1.5.1 --- Generation of strong oxidants --- p.24 / Chapter 1.5.2 --- Disinfection mechanism(s) --- p.27 / Chapter 1.5.3 --- Major factors affecting the process --- p.28 / Chapter 2. --- Objectives --- p.30 / Chapter 3. --- Materials and Methods --- p.31 / Chapter 3.1 --- Chemicals --- p.31 / Chapter 3.2 --- Bacterial strains and culture --- p.31 / Chapter 3.3 --- Photocatalytic reactor --- p.33 / Chapter 3.4 --- PCO efficacy tests --- p.33 / Chapter 3.5 --- PCO sensitivity tests --- p.35 / Chapter 3.6 --- Optimisation of PCO conditions --- p.35 / Chapter 3.6.1 --- Optimization of TiO2 concentration --- p.36 / Chapter 3.6.2 --- Optimization of UV intensity --- p.36 / Chapter 3.6.3 --- Optimization of depth of reaction mixture --- p.36 / Chapter 3.6.4 --- Optimization of stirring rate --- p.37 / Chapter 3.6.5 --- Optimization of initial pH --- p.37 / Chapter 3.6.6 --- Optimization of treatment time and initial cell concentration --- p.37 / Chapter 3.6.7 --- Combinational optimization --- p.37 / Chapter 3.7 --- Transmission electron microscopy (TEM) --- p.38 / Chapter 3.8 --- Fatty acid profile analysis --- p.40 / Chapter 3.9 --- Total organic carbon (TOC) analysis --- p.42 / Chapter 3.10 --- UV-C irradiation --- p.44 / Chapter 3.11 --- Hyperchlorination --- p.44 / Chapter 3.12 --- Statistical analysis and replication --- p.45 / Chapter 3.13 --- Safety precautions --- p.45 / Chapter 4. --- Results --- p.46 / Chapter 4.1 --- Efficacy test --- p.46 / Chapter 4.2 --- PCO sensitivity --- p.47 / Chapter 4.3 --- Optimization of PCO conditions --- p.48 / Chapter 4.3.1 --- TiO2 concentration --- p.48 / Chapter 4.3.2 --- UV intensity --- p.48 / Chapter 4.3.3 --- Depth of reaction mixture --- p.51 / Chapter 4.3.4 --- Stirring rate --- p.56 / Chapter 4.3.5 --- Effect of initial pH --- p.56 / Chapter 4.3.6 --- Effect of treatment time and initial concentrations --- p.56 / Chapter 4.3.7 --- Combinational effects --- p.63 / Chapter 4.4 --- Transmission electron microscopy (TEM) --- p.66 / Chapter 4.4.1 --- Morphological changes induced by PCO --- p.66 / Chapter 4.4.2 --- Comparisons with changes caused by UV-C irradiation and chlorination --- p.67 / Chapter 4.5 --- Fatty acid profile analysis --- p.71 / Chapter 4.6 --- Total organic carbon (TOC) analysis --- p.73 / Chapter 4.7 --- UV-C irradiation --- p.74 / Chapter 4.8 --- Hyperchlorination --- p.74 / Chapter 5. --- Discussion --- p.76 / Chapter 5.1 --- Efficacy test --- p.76 / Chapter 5.2 --- PCO sensitivity --- p.76 / Chapter 5.3 --- Optimization of PCO conditions --- p.77 / Chapter 5.3.1 --- Effect of TiO2 concentration --- p.77 / Chapter 5.3.2 --- Effect of UV intensity --- p.78 / Chapter 5.3.3 --- Effect of depth of reaction mixture --- p.79 / Chapter 5.3.4 --- Effect of stirring rate --- p.79 / Chapter 5.3.5 --- Effect of initial pH --- p.80 / Chapter 5.3.6 --- Effect of treatment time and initial concentrations --- p.81 / Chapter 5.3.7 --- Combinational effect --- p.82 / Chapter 5.4 --- Transmission electron microscopy (TEM) --- p.83 / Chapter 5.4.1 --- Morphological changes induced by PCO --- p.83 / Chapter 5.4.2 --- Comparisons with changes caused by UV-C irradiation and chlorination --- p.85 / Chapter 5.5 --- Fatty acid profile analysis --- p.85 / Chapter 5.6 --- Total organic carbon (TOC) analysis --- p.86 / Chapter 5.7 --- Comparisons of the three disinfection methods --- p.88 / Chapter 6. --- Conclusion --- p.91 / Chapter 7. --- References --- p.95 / Chapter 8. --- Appendix --- p.113

When Biosand filters cannot be constructed with crushed quarry rock due to resource limitations, a suitable alternative filter media is needed. In this research, two crushed quarry rock alternatives were examined. Three bench-scale Biosand filters with crushed rock, beach sand, and heat-treated beach sand media were simultaneously dosed with Willamette River water seeded with K-12 E. coli for 31 days. Influent and effluent filtrate was analyzed for E. coli using 3M Petrifilm E. coli/Coliform plate counts; influent and effluent pH, conductivity, turbidity, dissolved oxygen, and temperature were monitored. All three filters achieved stable E. coli removal efficiencies of 99% or greater after filter maturation, suggesting that it is possible to effectively use beach sand and heat-treated beach sand in Biosand filters for pathogenic bacteria removal. Mean effluent E. coli concentrations for crushed rock, beach sand, and heat-treated beach sand filters were 12, 29, and 30 CFU/mL respectively. Crushed rock filter effluent was significantly lower in mean effluent E. coli concentration than beach sand (P < 0.001) and heat-treated beach sand (P < 0.001) filter effluents, suggesting that beach sand and heat-treated beach sand media should only be used as a secondary option to crushed rock media due to potentially greater exposure risk to pathogenic bacteria. / Graduation date: 2013

Water is becoming increasingly scarce as the demand for fresh water continues to rise. One potential new water resource is purified produced water. Produced water is generated during oil and gas production, and it is often contaminated with emulsified oil, high levels of salt, and particulate matter. Produced water purification using polymer membranes has been investigated, but its implementation is limited by membrane fouling. This study focused on the preparation and application of poly(ethylene glycol) (PEG) hydrogels as fouling-resistant coatings for commercial reverse osmosis (RO) membranes. To prepare fouling-resistant coatings for RO membranes, three series of copolymer hydrogel networks were synthesized using poly(ethylene glycol) diacrylate (PEGDA) as the crosslinker and acrylic acid (AA), 2-hydroxyethyl acrylate (HEA), or poly(ethylene glycol) acrylate (PEGA) as comonomers, and their transport properties were evaluated. The hydrogels have high water uptake and high water permeability, and crosslink density strongly influences water uptake and water permeability. For example, a 100 mol% PEGDA hydrogel contained 61% water by volume, but 80PEGA, which has essentially the same chemical composition but lower crosslink density, contained 72% water by volume. Hydrogel water permeability ranged from 10 to 26 (L [mu]m)/(m² hr bar) and correlates well with water uptake; high water uptake often leads to high water permeability. Additionally, the copolymers have hydrophilic surfaces with a low affinity for oil, based on contact angle measurements using n-decane in water. Commercial RO membranes (AG RO membrane from GE Water and Process Technologies) were coated with PEG hydrogels, and the desalination and fouling resistance properties of the coated membranes were tested. The water flux of coated membranes and a series-resistance model were used to estimate coating thickness; the coatings were approximately 2 [mu]m thick. NaCl rejection for both uncoated and coated membranes was 99.0% or greater. As determined by zeta potential measurements, both uncoated and coated RO membranes are negatively-charged, but coated membranes are less negatively-charged than uncoated RO membranes. Model oil/water emulsions, prepared with either a cationic or an anionic surfactant, were used to probe membrane fouling. In the absence of oil, surfactant charge, and therefore, electrostatic interactions play a significant role in membrane fouling. In the presence of DTAB, a cationic surfactant, the AG RO membrane water flux immediately dropped to 30% of its initial value, but in the presence of SDS, an anionic surfactant, its water flux gradually decreased to 74% of its initial value after 24 hours. However, in both cases, coated membranes exhibited less flux decline than uncoated membranes. Coated membranes also experienced little fouling in the presence of an n-decane/DTAB emulsion. After 24 hours, the water flux of a PEGDA-coated AG RO membrane was 73% of its initial value, while the water flux of an AG RO membrane fell to 26% of its initial value. Conversely, both coated and uncoated membranes fouled significantly in the presence of an n-decane/SDS emulsion, indicating that oil fouling is controlled both by electrostatic and hydrophobic interactions. Overall, this work provides answers to some of the fundamental questions posed regarding the viability of using modified membranes for produced water treatment. / text

M. Tech. Chemical and Metallurgical Engineering / Focuses on developing a reproducible, regenerable, effective and affordable adsorbent for the removal of fluoride, phosphorus and arsenic from water. The adsorption media should perform at room or low temperatures. To perform basic mathematical modelling to aid in adsorber design. The specific objectives are as follows: to apply a simple thermo-chemical process to convert limestone into a robust adsorption media ; to pelletize thermo-chemically converted limestone using organic binders ; to determine the effect of binders on arsenic, fluoride and phosphate removal from water and to apply basic models to interpret breakthrough results.

Access to safe drinking water is an important health factor in many developing countries. Studies have shown that unsafe drinking water and poor sanitation practices leads to diarrheal disease, which is one of the leading causes of death of children under five in developing countries. Provision and proper use of household water filters have been shown to effectively improve health. This thesis is focused on the refinement and validation of algorithms for data collected from pressure transducer sensors that are used in household water filters (the Vestergaard Frandsen LifeStraw Family 2.0) deployed in Rwanda by the social enterprise DelAgua Health. Statistical and signal processing techniques were used to detect the use of the LifeStraw water filters and to estimate the amount of water filtered at the time of usage. An algorithm developed by Dr. Carson Wick at Georgia Institute of Technology was the baseline for the analysis of the data. The algorithm was then refined based on data collected in the SweetLab at Portland State University, which was then applied to field data. Laboratory results indicated that the mean error of the improved algorithm is 11.5% as compared with the baseline algorithm mean error of 39%. The validation of the algorithm with field data yielded a mean error of 5%. Errors may be attributed to real-world behavior of the water filter, electronic noise, ambient temperature, and variations in the approximation made to the field data. This work also presents some consideration of the algorithm applied to soft-sided water backpacks.

M.Tech. / Studies on the removal of nickel and platinum are increasing due to the toxicities of these metals. Several methods are currently used to extract these metals however they present limitations. There is hence a need to develop an efficient method for the removal of nickel and platinum from aqueous solution. A study on the use of purified multiwalled carbon nanotubes (purified MWCNTs) and a phosphine derivatized multiwalled carbon nanotubes for the extraction of these metal ions from solution was therefore undertaken. Multiwalled carbon nanotubes (MWCNTs) were produced by nebulised spray pyrolysis, purified by a multi-step technique and functionalized. Phosphine moieties were attached to the bromoarylated- MWCNTs by metallated phosphide route leading to triphenylphoshine linked MWCNTs (Tpp-MWCNTs). As produced, purified and triphenylphosphine linked multiwalled carbon nanotubes were characterized by various techniques, including microscopic and spectroscopic techniques, thermal, elemental and surface analysis. Transmission and scanning electron microscopy used revealed purified MWCNTs had insignificant impurities. X-ray photoelectron spectroscopy (XPS) results showed that triphenylphosphine linked multiwalled carbon nanotubes had 2.6% phosphorus. Zeta potential results demonstrated that purified MWCNTs had positive surface charges at acidic pH. Triphenylphosphine linked multiwalled carbon nanotubes were negatively charged on the surface in acidic media. Batch adsorption experiments were carried out to investigate the removal of nickel and platinum from aqueous solutions. Several parameters which influence the adsorption process were studied, including the effect of pH, the contact time and the effect of initial concentration on adsorption. The adsorption models for the Freundlich and Langmuir isotherms were employed to fit the experimental data. Triphenylphosphine linked MWCNTs removed more nickel (84.68 mg/g) than purified MWCNTs (77.39 mg/g). In contrast, purified MWCNTs removed more platinum (10.5 mg/g) than triphenylphosphine linked MWCNTs (6.01 mg/g). Experimental data for nickel fitted both Freundlich and Langmuir models well whereas only Langmuir model fitted well for platinum. The adsorption of nickel and platinum was indeed found to be pH, time and initial concentration dependent. Metal species (nickel and platinum) in solution had also influenced the uptake of these metals using purified-and Tpp-MWCNTs.

M. Tech (Department of Biotechnology, Faculty of Applied and Computer Sciences) Vaal University of Technology. / The presence of enteric viruses in drinking water poses a health risk to consumers. It is therefore very important for drinking water suppliers to provide water that is pathogen free and fit for human consumption. This can be achieved by an effective water treatment system that ensures the safety of water from the treatment plant until the water reaches the consumer. This study assessed the ability of a conventional water treatment system to remove viruses. The system consisted of three unit processes, namely, clarification, sand filtration and disinfection. These processes were simulated on a bench-scale to determine the effectiveness of each one at removing viruses. Clarification was conducted using a Phipps and Bird jar testing system and three different chemical treatments: (i) Polyelectrolyte (SUDFLOC 3835), (ii) a combination of lime and activated silica and (iii) a combination of lime, activated silica and ferric chloride. Sand filtration was simulated using a Phipps and Bird column filtration system. Disinfection was conducted using free chlorine. The findings from this study showed that the removal or inactivation of viruses increased with an increase in the concentration of chemicals added. For clarification, the combination of lime, activated silica and ferric chloride was the most effective treatment for the removal or inactivation of viruses. Sand filtration was found to be ineffective for the removal of viruses. Disinfection was shown to be the most effective process for the removal or inactivation of viruses. While clarification, sand filtration and disinfection did not remove or inactivate viruses equally, the entire treatment chain is still essential. This is because even if a barrier does not directly remove viruses it ensures that subsequent processes can function effectively. Overall the treatment processes should not be considered as discrete barriers but rather an integrated system that must function throughout to avoid a risk to customers.