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The main objective of the research was to investigate the effect of influent organic compounds on the performance of biological nutrient removal system. To carry out the investigation, a pilot plant system was designed and constructed. The system was operated as a UCT process at an influent flow rate of 0.15 liters/minute and a sludge age of 13 days. The influent wastewater was domestic sewage. Excess biological phosphorus removal and steady-state conditions were established before making experimental measurements, or adding supplemental substrate. The effects of separate addition of formic, acetic, propionic, butyric, isobutyric, valeric, and isovaleric acid, plus glucose, addition on phosphorus release under anaerobic conditions, and phosphorus uptake under aerobic conditions, were studied. The effects of the organic acid additions on the removal of nitrogen and COD, and changes in SOUR, MLVSS, and metals such as iron, magnesium, calcium and potassium, were also studied. In all experiments, the specific substrate was added continuously to the first anaerobic reactor for three days at an influent concentration of 100 mg COD/liter. Samples were collected from each reactor at the end of the addition period and analyzed for orthophosphate, nitrate, nitrite, sulfate, volatile fatty acids, COD, MLVSS, pH and metals. All added substrates, except formic acid and dextrose, caused significant increases in phosphorus release in the anaerobic stage, and phosphorus uptake, in the aerobic stage, and consequently, an increase in phosphorus removal efficiency. The molar ratios of phosphorus release to volatile fatty acid added obtained for propionic acid, acetic acid, butyric acid, and valeric acid were 0.44, 0.77, 0.78, and 1.72 respectively. However, on a COD basis, the greatest ratios of mg phosphorus released to mg COD utilized was produced by the addition of acetic acid (0.37) and valeric acid (0.19). It was also found that the branched organic acids, isobutyric and isovaleric, caused more phosphorus release in the anaerobic stage and better phosphorus removal efficiencies as compared with the nonbranching forms of the same organic acids. The molar ratios of phosphorus release for these two acids were 0.8 and 2.3, respectively, and on a COD basis were 0.16 and 0.25. For engineering applications, it is suggested by this research that at least 20 mg COD equivalent of acetic acid is needed for the removal of I mg phosphorus. The results obtained by this investigation were consistent with the hypothesis proposed by Marais et al., 1983. The most recent biochemical models, proposed by Comeau et al., 1986 and Wentzel et al., 1986, were also tested using the data collected in the present investigation. Both models, in most cases, overestimated the ratios of phosphorus release to volatile fatty acid utilized. A speculative model for anaerobic metabolism by poly-p bacteria of volatile fatty acids which contain both odd and even numbers of carbon atoms was proposed. All added substrates produced no effect on both COD and TKN removals. Metal releases were found to correlate with the amount of phosphorus release. / Ph. D.

The molecular size, charge, and solubility, distributions of natural DOC in raw and treated surface waters were investigated to determine the types of organic compounds removed by coagulation and settling. The distribution of organic precursors that react with chlorine to form organic halide compounds was also determined, along with the reaction rates. DOC removal by coagulation was size dependent. Compounds over 5,000 d were readily removed while compounds under 1,000 d were largely unaffected. Acidic and basic molecules were precipitated much more effectively than neutral ones. Both hydrophilic and hydrophobic molecules were selectively removed compared to compounds of intermediate solubility. Two groups of organic halide precursors were identified. Fulvic acids had high specific organic halide yields, and fast reaction rates with chlorine, but could be effectively removed by coagulation. Nonpolar neutral compounds were lower in molecular weight, slower to react with chlorine, and produced less organic halide, but could not be precipitated by coagulation. / Ph. D. / incomplete_metadata

The objectives of this study were to determine the optimum operating conditions required for air stripping of ammonium sulfate wastewater from the caprolactam manufacturing process, to determine if biological nitrification is a viable means of treatment, and to identify any compounds present in the ammonium sulfate wastewater that (might) inhibit nitrification. This was accomplished using a combination of air stripping pretreatment, a flow-through conventional activated sludge system, powdered activated carbon (PAC) treatment and batch testing. Although biological treatment was conducted using conditions to promote nitrifier growth, nitrification was not observed using either conventional or PAC treatment. Air stripping removed fifty per cent of the ammonia-nitrogen at gas-to-liquid ratios greater than 500. However, it had no apparent effect on nitrifier inhibition. Inhibitor studies of this waste stream focused on two oximes: namely cyclohexanone oxime and methylethyl ketoxime (MEKO), which were both found in the wastewater in concentrations of 50-150 mg/L. The conclusion of this work is that cyclohexanone oxime is not inhibitory to nitrification .in concentrations less than 100 mg/L; however, MBKO was found to be inhibitory at concentrations as low as 14 mg/L. Furthermore, the inhibitory effect appeared to be pH dependent with increasing inhibition at pH less than eight. The implications of these findings for the design and operation of a full-scale treatment facility are numerous. The optimum pH range for a full-scale facility would be narrow due to the requirement for a pH high enough to decompose MEKO while maintaining a pH low enough to prevent free ammonia toxicity. / M.S.

The objectives of this project were: 1) to ascertain the feasibility of using a two-stage foam separation system, with foam fractionation or air flotation as the second stage, to treat a tarsand extraction wastewater; and, 2) to evaluate the effects of four operational variables on the second stage performance. The wastewater was a tar-in-water emulsion collected during a steamflood extraction experiment conducted by the Department of Energy's Laramie Energy Technology Center on a tarsand deposit in eastern Utah. The four operational variables considered were chemical dose, hydraulic detention time, air flowrate, and temperature. To achieve these objectives a two-stage system was devised. In the first stage, polymer-aided air flotation removed the bulk of the tar. With the second-stage foam fractionation system, 16 trials were conducted using the cationic surfactant, EHDA-Br. In the second-stage air flotation system, 24 trials were conducted, eight with no polymer addition and 16 with the addition of the low molecular weight, strongly cationic polyelectrolyte, Betz 1195. Ten trials were then conducted at the set of conditions believed to give the best treatment of the water. The effluents were tested for TOC, COD, suspended solids (SS), and total solids. It was found that either of the two-stage systems would give TOC, COD, and SS reductions greater than 98 percent, although the polymer-aided air flotation system was found to be the best second stage process. The replicate trials consistently produced data very close to the best treatment achieved in the experimental trials, thus showing the reproducibility and stability of the two-stage process. / M. S.

Submitted in fulfillment of the requirements for the degree of Master of Engineering in Chemical Engineering, Durban University of Technology. Durban. South Africa, 2015. / Several areas in the world such as the United States of America, Sri Lanka, China, Argentina, Canada, Tanzania, Kenya, South Africa and many others have a problem of high fluoride content in drinking water. Generally fluoride levels above 1.5 ppm in water may result in dental and skeletal fluorosis in humans depending on quantity consumed (Fan et al., 2003; Meenakshi, 2004). Remote rural areas where there are no water treatment facilities are more vulnerable to this problem. Adsorbents such as activated alumina and FR-10 resin seem to have a potential for successful application in rural areas. These methods however require pre-treatment if the feed has high turbidity. A membrane based system called woven fabric microfiltration gravity filter (WFMFGF) developed by Durban University of Technology proved to be suitable for turbidity removal. The main objective of this research was to develop a small water treatment system for fluoride removal. The small water treatment system developed in this study consists of WFMFGF for pre-treatment and an adsorption column. The WFMFGF is made up of a 40 L container packed with 15 immersed flat sheet membrane elements. The operation of the WFMFGF is in batch mode, driven by varying static head. The static head variation results in flow rate variation through the system. This in turn result in variation of contact time, velocity as well as pressure drop in the fluoride removal unit. Specific objectives of the study were: (1) to establish the maximum and minimum flow rates through the WFMFGF system, the total run time before cleaning is required and the best cleaning method for this particular membrane system. (2) to evaluate and compare the performance of activated alumina and FR-10 resin on varying contact time, velocity and pressure drop on the fluoride removal unit. The adsorbents were also compared on adsorption capacity, cost and ease of operation. The minimum and maximum flow rates through the WFMFGF were found to be 5 l/hr and 100 l/hr respectively. It was found that the system can be run for more than a month before requiring cleaning. The suitable cleaning method was found to be soaking the membranes in 0.0225 percent sodium hypochlorite solution overnight and brushing them using a plastic brush. The comparison of the performance of FR-10 resin to activated alumina found that the adsorbents gave equal performance based on the given criteria. FR-10 resin had higher adsorption capacity, gave good quality treated water even with shorter contact time and operated at wider velocity range. Activated alumina on the other hand had an advantage of lower costs, lower pressure drop and ease of use. According to Pontius (1990), the performance of activated alumina can be improved by intermittent operation. Point of use (POU) systems are generally operated intermittently. This improves the fluoride removal efficiency of activated alumina giving it more advantage over FR-10 resin. Based on this activated alumina was selected as the best adsorbent for the system. After the adsorbent was selected, the adsorption column was designed. The column operation regime was 3.5 minutes minimum contact time and 1.17 to 7.8 m/hr velocity range. The activated alumina adsorption capacity was 1.53mg/g. The column had an inside diameter of 70 mm. It was packed with activated alumina to a bed height of 400 mm. The column inlet and outlet pipes were made of PVC with a standard pipe size of 20 mm outside diameter. A valve at the column inlet pipe allowed water to flow through the system.

This dissertation surveyed the validities of teaching the chemistry of water purification in South African schools using locally available materials (LAM) through the scientific inquiry (SI) approach. The researcher randomly selected four secondary schools that provided a small and purposive study sample of thirty-two Grade 11 learners and four teachers. The research design applied a mixed-method approach, consisting of qualitative and quantitative methods of data collection. Within this approach, the outcome of SI instruction that integrated LAM was compared with that of conventional instruction through a quasi-experimental control groups design. The researcher identified in the analysis of interviews and questionnaires the most complex aspects of the chemistry of water purification for learners to understand as redox reactions, acid-base systems, precipitations, and chlorination. However, the use of LAM through the scientific inquiry approach made it easier for learners to understand the concepts. The high mean scores ( =80.88; SD=10.28) in Research-based Test 2 (RBT2), of the experimental groups taught through SI signified that those learners immensely benefited from an active and collaborative learning environment. The lowly scores ( =61.69; SD=4.21) of control groups could be attributed to a linear and passive participation of learners in the conventional classroom instruction. The marks of the two groups in post-test RBT2 were paired and contrasted using GraphPad software. The results showed that t =6.699, df =21 with a significant value of 0.0001, which is less than 0.05 (p<0.05), hence it can be inferred that the difference between the means of the two groups was not only statistically important but also worth an explanation. The higher performance scores in RBT2 and the Rubric Assessment Tool (RAT) in experimental groups represents that the intervention was successful in the implementation of instructional design in the the study. In addition, the learners had mastered the crucial aptitudes that included self-discipline in understanding, cooperative learning, searching relevant text on topic, hands-on or laboratory practice and logical thinking in problem solving by working through the SI activities that used LAM. / Mathematics, Science and Technology Education / M. Sc. (Mathematics, Science and Technology Education with specialization in Chemistry Education)

The objective of this study was to investigate the feasibility of the application of low cost high capacity inorganic ion exchange material, synthesized form collected fly ash and acid mine drainage solid residues, for the decontamination of secondary co-disposal process waters, with emphasis on investigating the processes governing the solid/solution interface.

This dissertation surveyed the validities of teaching the chemistry of water purification in South African schools using locally available materials (LAM) through the scientific inquiry (SI) approach. The researcher randomly selected four secondary schools that provided a small and purposive study sample of thirty-two Grade 11 learners and four teachers. The research design applied a mixed-method approach, consisting of qualitative and quantitative methods of data collection. Within this approach, the outcome of SI instruction that integrated LAM was compared with that of conventional instruction through a quasi-experimental control groups design. The researcher identified in the analysis of interviews and questionnaires the most complex aspects of the chemistry of water purification for learners to understand as redox reactions, acid-base systems, precipitations, and chlorination. However, the use of LAM through the scientific inquiry approach made it easier for learners to understand the concepts. The high mean scores ( =80.88; SD=10.28) in Research-based Test 2 (RBT2), of the experimental groups taught through SI signified that those learners immensely benefited from an active and collaborative learning environment. The lowly scores ( =61.69; SD=4.21) of control groups could be attributed to a linear and passive participation of learners in the conventional classroom instruction. The marks of the two groups in post-test RBT2 were paired and contrasted using GraphPad software. The results showed that t =6.699, df =21 with a significant value of 0.0001, which is less than 0.05 (p<0.05), hence it can be inferred that the difference between the means of the two groups was not only statistically important but also worth an explanation. The higher performance scores in RBT2 and the Rubric Assessment Tool (RAT) in experimental groups represents that the intervention was successful in the implementation of instructional design in the the study. In addition, the learners had mastered the crucial aptitudes that included self-discipline in understanding, cooperative learning, searching relevant text on topic, hands-on or laboratory practice and logical thinking in problem solving by working through the SI activities that used LAM. / Mathematics, Science and Technology Education / M. Sc. (Mathematics, Science and Technology Education with specialization in Chemistry Education)