M.Ing. / Fouling and more specifically scaling is one of the most discussed and not yet well understood problems facing engineers. Scale formation which has enormous economic and environmental consequences does not only influence heat transfer characteristics and pressure drop through tubes, but influence the volumetric flow rate as well. To solve this problem Physical Water Treatment (PWT) devices have been developed which reportedly reduce scale formation. The efficiency of PWT devices is a controversial subject and many contradictions exits in the claimed effect. Researchers have been trying to prove the efficiency of PWT devices but in most cases the results are typically characterised by low reproducibility. An experimental measuring technique is thus required to measure scale formation and the influence PWT devices has on scaling. This technique must also produce reproducible results to clarify the questions surrounding PWT devices. This thesis is an experimental investigation in which an experimental setup and measuring technique is developed. It is used to evaluate a permanent magnet for the decrease of scale formation in tubes. The volumetric flow rate is used as the indicator of scale formation, which relies on the basic principle that the friction pressure drop increases if scaling takes place. The volumetric flow rate is monitored by measuring the time necessary to fill a container of known volume. The test section consists of three soft drawn copper tubes in which water with a velocity of ± 2 m/s flows. One of the tubes is used to evaluate the PWT device and the other two tubes are used as a control. The water temperature is kept at 53°C. The experiments are done in five phases in which the PWT device is placed onto one of the tubes in phase four and removed in phase five. It follows from the results obtained that a very sensitive experimental setup was designed and built which can be used to evaluate the efficiency of PWT devices. It follows from the variation in time necessary to fill the container in phase four and five that a clear conclusion can not be made. More experiments must be done in which reproducible results are obtained.

The potential of using mushroom polyphenol oxidase (EC 1.14.18.1) as a biocatalyst for the biotransformation of phenols to produce catechols in an aqueous medium was investigated. Polyphenol oxidase is characterised by two distinct reactions i.e., the ortho-hydroxylation of phenols to catechols (cresolase activity) and the subsequent oxidation of catechols to orthoquinones (catecholase activity). In order to facilitate the development of a process to produce catechols, the accumulation of catechol as a true intermediate product released in the reaction system needed to be investigated, as its release had been disputed due to the oxidation of catechols to o-quinones. Using LC-MS, catechol products were successfully identified as true intermediate products formed during biocatalytic reactions in water.

M.Dip.Tech.(Environmental Health) / At the onset of this project the aim was to utilise fly ash, supplemented with lime, to stabilise sewage sludge, in so doing create an artificial soil. This would be an environmentally friendly method of disposing of both the fly ash 'and the sewage sludge which are both considered wastes. The sewage sludge was pasteurised by the temperature produced by the exothermic reaction between the moisture ofthe sewage sludge and the high pH ofthe fly ash and the lime. Initially very high concentrations of lime were utilised to achieve the pasteurisation of the sewage sludge. These levels proved to be adequate to completely sterilise the sludge, rather than pasteurise it, as temperatures in excess of 1000e were obtained and maintained for a prolonged period. The product, SLASH, should ideally maintain some of the non-pathogenic microorganisms to facilitate natural degradation processes in the soil. .It was thus decided to minimise the lime addition and maximise the ash usage without losing the necessary soil-like texture of the SLASH product and still insuring pasteurisation. Various 10kg tests were conducted on differing ratios of sewage sludge, ash and lime. The mixtures were contained in insulated 220 litre drums in order to ensure a minimum of interference from environmental factors. The tests were conducted with the drums sealed and unsealed, as well as with coarse and finely milled lime-stone. These laboratory scale tests led to the establishment of a preferred 6:3:1 ratio ofsewage sludge to ash to lime. After an international visit to a plant manufacturing a similar product, it was suggested that the ratio be amended to 6.3:3.4:0.6 of sewage sludge to ash to lime. Tests showed that although the temperatures obtained when using this ratio were insufficient for pasteurisation, pasteurisation did occur. This was attributed to the maintenance of the pH of the product above 12 for more than 24 hours. This severely stressed the microorgansims and they died. No pathogenic bacteria were detected in the analyses from these tests, but the total aerobic bacterial count indicated the presence of some microorganisms which would become part of the soils natural flora.

Ph.D. / Natural Organic Matter (NOM) consists of a highly variable mixture of products found in various types of water and soils, formed as a result of decomposition of plant and animal material into water. NOM is a precursor for the formation of disinfection by-products (DBPs) during water disinfection. It causes undesirable colour, taste and odour in water. The reduction of NOM affects the capacity of other treatment processes to remove organic micro-pollutants or inorganic species that may be present in the water. The differing levels and composition of NOM in South African water sources in different regions suggests that a water treatment strategy by a treatment plant should address the issues relating to specific NOM and its treatability. Therefore, in order to reduce NOM from water in a water treatment train, the composition of the NOM in the source water must be taken into account, since its composition at any given time may depend on the local prevailing conditions. The primary objective of this study was therefore to characterize NOM present in South African source waters through extensive sampling of representative water types at identified regions in the country and develop a rapid NOM characterization protocol. Water samples were thus collected from eight different water treatment plants broadly located within the five major source water types of South Africa between the periods of February 2010 to June 2011 in five sampling rounds. The sampling campaigns were planned and timed in order to accommodate the dry and the rainy seasons. The water treatment plants sampled were: Loerie (L) Water Treatment Plant, Midvaal (M) Water Treatment Plant, Olifantsvlei (O) Wastewater Treatment Plant, Plettenberg Bay (P) Water Treatment Plant, Rietvlei (R) Water Treatment Plant, Umzoniana (U) Water Treatment Plant, Vereeniging (V) Water Treatment Plant, and the Wiggins (W) Water Treatment Plant. The L water is from a small impoundment, which is fed from the Kouga Dam. The M water is pumped from the Vaal River.

Ph.D. (Biochemistry) / Please refer to full text to view abstract

>Magister Scientiae - MSc / Fucoidan is a marine-derived sulphated polysaccharide with bioactive properties ideal for the food, chemical and pharmaceutical industries. The polysaccharide consists largely of L-fucose, has a highly heterogeneous structure and is of diverse origin. Fucoidan was extracted from Ecklonia maxima, Laminaria pallida and Splachnidium rugosum and the effect of different extraction methods on fucoidan heterogeneity was assessed. Extraction methods employed hot water, hydrochloric acid or calcium chloride salt. Fucoidan yield and purity were determined by various colorimetric assays. Highest fucoidan yield was obtained with the hot water extraction method as seen by highest L-fucose content. Splachnidium rugosum extracts contained ~5 times more L-fucose than Ecklonia maxima and Laminaria pallida extracts. The salt extraction method yielded extracts free of contaminants, however L-fucose content in all extracts was >20 times lower. Acid extraction yielded highest levels of uronic acid contamination and liberated sulphate from the fucoidan polysaccharide. The fucose-to-sulphate ratio for Ecklonia maxima was approximately 1:5, whilst the ratios for Splachnidium rugosum and Laminaria pallida were approximately 1:1 and 1:2, respectively. The acid and salt extraction methods removed all traces of protein contaminants, while the hot water method retained very low levels of protein. The extraction method used to isolate fucoidan was a determining factor in yield and purity. Chemical compositional analyses of hot water extracts were assessed by gas chromatography mass spectroscopy. Splachnidium rugosum and Laminaria pallida extracts consisted largely of L-fucose, while Ecklonia maxima fucoidan was characterized with high glucose abundance. Crude hot water and acid extracts from Splachnidium rugosum tissue were fractionated and purified by (anionic) ion exchange chromatography as bioactivity has been correlated to lower molecular weight forms. In water extracts, ion exchange chromatography resulted in close to 90% decrease in L-fucose, sulphate and uronic acid, while protein content increased by 57%. Similar results were reported for acid extracts; however protein content did not change significantly. These results show that method of extraction may affect the composition of fucoidan post-purification. Hot water extraction is recommended due to higher fucoidan yield, as reflected by L-fucose content, and higher sulphate-to-fucose ratio. High protein content after ion exchange chromatography was however of concern. Since mucilage in Splachnidium rugosum thallus was free of protein, fucoidan was precipitated from mucilage with ethanol. Fucoidan yield of mucilage was >15-fold higher than content in purified hot water extracts with a sulphate-to-fucose ratio of ~1:1. The average molecular weight of native fucoidan in mucilage was estimated at 2367 kDa. The polysaccharide was hydrolysed by gamma-irradiation levels of 10-50 kGy to fractions ranging between 60 and 15.5 kDa. Hot water crude fucoidan extracts from Ecklonia maxima, Laminaria pallida, and Splachnidium rugosum were assessed for anti-oxidant activity by measuring the ability to scavenge free radicals and the capacity to reduce copper ions with 2,2-Diphenyl-1-picrylhydrazyl and Cupric Reducing Anti-oxidant Capacity assays, respectively. Ecklonia maxima crude fucoidan displayed highest anti-oxidant activity and capacity, having the potential to scavenge reactive oxygen species as well as the capacity to reduce copper to less toxic forms in mammalian systems. Splachnidium rugosum showed weakest anti-oxidant activity and lowest reducing capacity. The anti-cancer activity of crude and purified hot water Splachnidium rugosum extracts, as well as non-irradiated (native) and gamma-irradiated fucoidan, and commercially procured fucoidan were assessed for anti-cancer activity against MCF-7 breast cancer cells. Splachnidium rugosum crude and purified fucoidan displayed a half maximal inhibitory concentration of 0.7 mg/mL and 0.029 mg/mL, respectively. Low cytotoxicity of crude and purified Splachnidium rugosum fucoidan against non-cancerous breast epithelial cell line MCF-12A was observed, as seen by half maximal inhibitory concentration values of 2 mg/mL and 0.663 mg/mL, respectively. The cancer specific selectivity of purified Splachnidium rugosum fucoidan was therefore much higher as reflected by 10-fold higher selectivity index than that of crude fucoidan. Native and low molecular weight gamma-irradiated fucoidan also showed bioactive properties including anti-cancer activity as seen by the reduction of cell proliferation in vitro, whereas crude fucoidan showed the ability to scavenge free radicals, and the capacity to reduce copper ions. / National Research Foundation (NRF)

The kinetics of direct reduction of a commercial unagglomerated iron ore, with low-rank coal chars, have been investigated in the temperature range of 800-950°C (1073-1223 K) using a laboratory-size rotary reactor. The variables studied were temperature, coal type, particle size of coal and ore, fixed carbon-to-iron ratio, rotational speed-and percent filling. In addition the effects of a catalyst on the Boudouard reaction and of inert gas flushing on the reduction rate were determined. Mixing studies at room temperature and at reduction temperature yielded the best mixing conditions prior to the kinetics determinations. Agglomeration between the reduced particles was also studied. The mixing experiments at room temperature yielded the following. The degree of mixing depends almost entirely on the coal-to-ore size ratio. Best mixing is achieved with values of this ratio of 1 and smaller, for ore particles larger than 254 µm; for smaller sizes than this, good mixing can be obtained at higher coal-to-ore size ratios. At reduction temperature, improvement in the reduction rate was not obtained either by further increasing the fixed carbon-to-iron ratio from 0.32 to 0.64 or by varying the rotational speed from 7 to 20 r.p.m.. In the kinetics experiments, the overall reduction process was found to be controlled up to 0.5 to 0.8 fractional reduction by the Boudouard reaction, depending on the particle size and temperature; from then on, the kinetics were controlled essentially by the reduction reaction. The activation energies obtained were 224 kJ/mole for the Boudouard reaction, using sub-bituminous coal char, and 264 kJ/mole using lignite coal char; these values correspond to that of a catalyzed reaction. The catalytic effect of the coal ash on the Boudouard reaction was found to be much larger than the respective effect of metallic iron. The presence of a diluent gas extended the fractional reduction over which Boudouard reaction control is exerted. The activation energy obtained for the reduction of wustite by CO is 116.4 kJ/mole. The analysis of the Pco/Pco₂ ratio produced by the reaction proved to be a powerful tool in elucidating the rate controlling step. Smaller ore particles were found to agglomerate considerably more, in the non-catalyzed experiments; the addition of a catalyst for the Boudouard reaction also produced larger agglomerates. In neither case did agglomeration retard the reduction rate to a considerable extent. No accretion growth was observed on the reactor wall. Estimative calculations showed that similar throughputs can be obtained by processing the unagglomerated concentrate, as compared to operations which utilize indurated pellets under the same conditions. An advantage of a process using concentrates is the lower temperature at which it can be operated. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

The principles behind anaerobic digestion are fairly well understood, but the limits of application of each digester design are not known. Because there are significant differences in the properties of the many wastewaters requiring treatment optimal anaerobic digester performance requires the matching of feed characteristics to a digester design and mode of operation. No consensus has yet emerged on digester design, operating conditions or feed/digester match-ups. In this study, three bench scale retained biomass anaerobic digester designs were examined for their response to a sequence of varied hydraulic retention times (HRTs) and influent wastewater concentrations. The digester designs studied were the upflow anaerobic filter, the upflow anaerobic expanded bed and the upflow anaerobic sludge bed. The wastewater was screened and diluted dairy cow manure obtained from the UBC dairy barn. The parameters monitored included the total and soluble chemical oxygen demand (TCOD and SCOD), volatile and suspended solids (VS and SS), total volatile fatty acids (VFAs), total Kjeldahl and ammonia nitrogen (TKN and NH₃-N), pH, biogas production, and the methane (CH₄) and carbon dioxide (C0₂) content of the biogas. Wastewater treatment efficiencies, measured in terms of TCOD, SCOD, VS, and TVFA removals, and methane productivity and methane yield for each of the digester designs were examined for the range of the operating conditions. The anaerobic filter digester effected a mean TCOD removal efficiency of 47% ± 14% at a mean 4.0 day HRT, 51% ± 9% at a mean 2.3 day HRT and 35% ± 11% at a mean 1.3 day HRT. The expanded bed digester effected a mean TCOD removal of 45% ± 15% at a mean 4.3 day HRT, 38% ± 12% at a mean 2.5 day HRT and 28% ± 9% at a mean 1.3 day HRT. The sludge bed digester effected a mean TCOD removal of 53% ± 9% at a mean 3.8 day HRT, 45% ± 12% at a mean 2.2 day HRT and 32% ± 10% at a mean 1.2 day HRT. For all three digesters, the difference in the treatment efficiency over the range of HRTs tested, from 5 to 1.25 days was not in proportion to the change in HRT. Methane productivity, measured against either the removal or addition of substrate in terms of TCOD, SCOD, VS and TVFA, demonstrated considerable variability. Methane production increased with both substrate addition and substrate removal. Methane yield increased with increasing HRT. The sludge bed digester generally exhibited the greatest but most variable methane yields. It produced 0.095 L CH₄/g VS added at a mean 3.8 day HRT and 0.037 L CH₄/g VS added at a mean 1.2 day HRT. The anaerobic filter delivered the greatest methane yield at the intermediate HRT, 0.044 L CH₄/g VS added at a mean 2.3 day HRT. The expanded bed demonstrated low methane yields over the range of feed strengths and HRTs tested. Biogas composition averaged 62.1% methane and 17.1% carbon dioxide for the anaerobic filter, 43.6% methane and 5.3% carbon dioxide for the expanded bed. and 61.1% methane and 18.9% carbon dioxide for the sludge bed. / Applied Science, Faculty of / Graduate

Leaching of chalcopyrite by Thiobacillus ferrooxidans under standard microbiological leaching conditions resulted in simultaneous solubilization of copper, iron and sulfur. The sulfide portion was oxidized preferentially over iron in solution suggesting a direct attack mechanism by the bacteria on the mineral particles. Copper extractions were low, 29-44%, with maximum specific copper extraction rates of the order of 0.001-0.006 h⁻¹ and cell yields per unit of copper released 4-43mg TOC/mg Cu. Leaching under redox-controlled conditions required a minimum pulp density, ca. 200 g/1, to result in elemental sulfur production. Some unknown factor, resulting from biological leaching activity under standard conditions and transferred with the liquid phase of the inoculum, was needed for the leach to occur under redox-controlled conditions. Copper extractions of 44-100% were achieved. Maximum specific copper extraction rates were of the order of 0.002-0.007 h⁻¹ with cell yield per unit of copper released of the order of 0.12-3.32mg TOC/g Cu for batch cultures. Ferrous iron in solution appeared to be the energy source for cell growth under redox-controlled conditions. The cells' sulfide oxidizing capacity seemed to be inhibited at the metabolic regulation level and not at the enzyme synthesis level. Cells growing under the standard conditions underwent a lag phase, upon transfer to the redox-controlled medium. During this lag phase low metal solubilization rates and low S⁰ production occurred, but when cell growth started, the leaching rates increased and the mineral dissolved rapidly. Electron diffraction X-ray analyses were carried out to investigate the role of silver in the controlled-redox leaching. No silver was observed to be on the surface of the chalcopyrite particles before or after the initial activation stage of the controlled-redox process. Silver deposits were observed after many hours of leaching. A mathematical model to describe the kinetics of microbial leaching, using a shrinking particle concept as its basis, was developed. When tested against data from the literature for leaching of Zinc from ZnS concentrate it was able to predict particle size as a function of leach time. It also gave reasonable predictions of particle size as a function of leach time for standard leaching of chalcopyrite but failed to predict accurate values for particle size as a function of leach time for the controlled-redox process. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

The extraction, separation and identification of volatile organic components of primary effluent before and after chlorination was undertaken to ascertain whether the chlorination of treatment plant effluents results in the formation of new volatile chlorinated organics. Extraction efficiencies of 70 to 90 percent of an aqueous solution of phenols were obtained by both continuous solvent extraction and sorption on a column of a macroreticular resin. Tests with primary effluent showed that the macroreticular resin recovered a slightly larger number of compounds than the solvent extractor which also suffered from emulsion problems.' Since the resin was also expedient in handling replicate samples it was adopted and further studies indicated that it had a capacity of 1.7 mg TOC/cc of resin and recoveries of the phenols were unaffected by pH or detergents. Preliminary separation of the. .components on the basis of acidity with .05'M^NaOH and diethyl ether and by thin layer chromatography on silica gel with pet ether and methanol proved to be useful. Gas chromatographic (GC) studies with various silicone liquid phases demonstrated that OV-101, 0V-17, and 0V-225 all provide good separation after optimization of temperature programs. Primary effluent samples taken from Lion's Gate Treatment Plant in North Vancouver on Monday mornings proved to be remarkably consistent in their GC 63 traces as monitored by Ni electron capture (EG) and flame ionization (FID) detectors. A series of spectacular new peaks was consistently observed by EC as a result of chlorination, but the FID showed only minor changes. Dosage levels of up to 120 mg/1 Cl₂ (NaOCl) produced similar chromatograms while a dosage of 200 mg/1 produced a new set of changes not found at the dosage levels used in treatment plants. Gas chromatographic studies with a micro- electrolytic conductivity detector showed that 10 or 11 new halogenated peaks in the neutral and basic fraction and 6 or 7 new halogenated peaks in the acidic fraction result from chlorination. These compounds all of which are in μg/l concentrations account for only 0.01 percent of the applied chlorine dosage but make up about 40 percent of the more volatile organically bound halogen present in chlorinated primary effluent. After a series of partially successful attempts by retention time, GC-MS and GC effluent trapping, a number of components were positively identified by a computerized GC-MS. TRirty-one compounds were positively identified by mass spectra and GC retention times, another 24 were tentatively identified by mass spectra and an additional seven were very tentatively identified by GC retention times. Only three of the compounds resulting from chlorination were positively identified. All compounds identified by mass spectra are present in concentrations in primary effluent. The implications of this study and suggestions for further investigations are also discussed. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate