Fish and crab processing wastes were ground and ensiled with corn stover or peanut hulls alone and with 5% dry molasses or 1% formic acid in 3.8 liter cardboard containers double lined with polyethylene. The wastes and roughages were ensiled in proportion to give dry matter levels of 40, 50 and 60%. The seafood wastes were also ensiled with wilted Johnsongrass with and without molasses. After ensiling, average pH for mixtures with fish waste was 6.5, compared to 8.0 for mixtures with crab waste. Addition of dry molasses resulted in a decrease (P <.01) of pH to 5.6 for the ensiled fish mixture but had no effect on the crab waste mixtures. Lactic acid was higher (P< .01) for ensiled mixtures containing fish waste than for those containing crab waste. Substantial levels of acetic acid were present in the silages. Butyric acid levels were higher in silages containing crab waste and decreased linearly (P< .01) with increased dry matter levels. Desirable ensiling was observed for the mixture of fish waste and Johnsongrass. Coliforms and fecal coliforms were decreased or elIminated by ensiling. In a large silo study, mixtures of finfish and crab processing wastes were mixed with wheat straw and ensiled in 210 liter metal drums, double lined with polyethylene bags. Proportions of the fish and straw were 70:30 and 51:49, wet basis, while that of the crab was 60:40 and 40:60. Acetic acid was added to the crab waste mixtures to lower the initial pH to 4.5. After ensiling all mixtures containing fish and straw showed a decrease in pH. Addition of acetic acid to mixtures containing crab waste inhibited fermentation, but resulted in a very stable product. In a sheep digestion trial, dry matter digestibility was higher (P <.01) for the 70:30 diet than for the 51:49 fish diet. There was no difference in dry matter digestibility between the crab silages. Crude protein digestibility was higher (P <.01) for diets containing ensiled fish, compared to diets containing ensiled crab. Nitrogen retention was positive for sheep receiving all diets. Nitrogen retention was higher (P <.01) for animals fed the crab silage diets, compared to those receiving diets containing fish silage. There was a trend for P absorption to be higher in animals fed crab silage. In the sheep palatability trial, intake of dry matter was higher (P < .01) for sheep consuming the crab silage diet and lowest (P <.01) for sheep fed the 70:30 fish silage diet. / Ph. D.

In recent years, a compound N-nitrosodimethylamine (NDMA), a probable human carcinogen, has been identified as an emerging disinfection by-product (DBP) since its formation and detection were linked to chlorine-based disinfection processes in several water utilities in the U.S. and Canada. Numerous organic nitrogen compounds present in water may impact the formation of NDMA during disinfection. Amine-based water treatment polymers used as coagulants and flocculants have been suggested as potential NDMA precursors due to the presence of amine functional groups in their structures, as well as the possible presence of dimethylamine (DMA) residues in polymer products. To minimize the potential risk of NDMA associated with water treatment polymers, the mechanisms of how the polymers behave as NDMA precursors and their contribution to the overall NDMA formation under actual water treatment conditions need to be elucidated. This research involved a systematic investigation to determine whether amine-based water treatment polymers contribute to NDMA formation under drinking water and wastewater treatment conditions, to probe the involved reaction mechanisms, and to develop strategies to minimize the polymers NDMA formation potential. The investigation included five research tasks: (1) General screening of NDMA formation potential of commonly used amine-based water treatment polymers, (2) NDMA formation from amine-based water treatment polymers under relevant water treatment conditions, (3) Probing the mechanisms of NDMA formation from polyamine and PolyDADMAC, (4) Effect of water treatment processes on NDMA formation from amine-based water treatment polymers, and (5) Developing strategies to reduce polymers NDMA formation potential. Direct chloramination or chlorination of high doses of polymers in deionized water at longer than typical contact time was used in the general screening of the NDMA formation potential of water treatment polymers and in the studies to identify reaction mechanisms. On the other hand, realistic dosages of chloramines and polymers and contact time were used in simulating representative water treatment conditions to evaluate the contribution of polymers to the overall NDMA formation in real systems. On the basis of the study results, strategies were developed to reduce the NDMA formation potential of amine-based water treatment polymers, which include modification of polymer structures and treatment parameters.

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Whereas fuel used for transport and electricity production are mainly fossil–derived, there has recently been an increased focus on bio-fuels due to the impact of fossil derived fuel on the environment as well as the increased energy demand worldwide, concomitant with the depletion of fossil fuel reserves. Paper sludge produced by paper mills are high in lignocellulose and represents a largely untapped feedstock for bio-energy production. The aim of this study was to determine the composition, fermentability and optimum paper sludge loading and enzyme dosage for producing ethanol from paper sludge. This information was used to develop a model of the process in Aspen Plus®. The mass and energy balances obtained from the Aspen Plus® model were used to develop equipment specifications which were used to source equipment cost data. A techno-economic model was developed from the equipment cost data to assess the economic viability of the simultaneous saccharification and fermentation (SSF) process utilising paper sludge as feedstock. Nine paper sludge samples obtained from Nampak Tissue (Pty) Ltd. were evaluated in terms of ethanol production and those samples yielding the highest and lowest ethanol titres were selected for optimisation. This allowed for the determination of a range of ethanol concentrations and yields, expressed as percentage of the theoretical maximum, which could be expected on an industrial scale. Response surface methodology was used to obtain quadratic mathematical models to determine the effects of solid loading and cellulase dosage on ethanol production and ethanol yield from paper sludge during anoxic fed-batch fermentations using Saccharomyces cerevisiae strain MH1000. This approach was augmented with a multi response optimisation approach incorporating a desirability function to determine the optimal solid loading and cellulase dosage in fed-batch SSF cultures. The multi response optimisation revealed that an optimum paper sludge loading of 21% (w/w) and a cellulase loading of 14.5 FPU g-1 be used regardless of the paper sludge sample. The fact that one optimal enzyme dosage and paper sludge loading is possible, regardless the paper sludge feed stock, is attractive since the SSF process can be controlled efficiently, while not requiring process alterations to optimize ethanol production when different batches of paper sludge are processed. At the optimum paper sludge loading and cellulase dosage a minimum ethanol concentration of 47.36 g l-1 (84.69% of theoretical maximum) can be expected regardless of the paper sludge used. An economic assessment was conducted to ascertain whether ethanol production from paper sludge using SSF is economically viable. Three scenarios were investigated. In the first scenario revenue was calculated from the ethanol sales linked to the basic fuel price, whereas in the second and third scenarios liquefied petroleum gas (LPG) consumption at the paper mill was replaced with anhydrous and 95% ethanol respectively. In all the cases, paper sludge feed rates of 15, 30 and 50 t d-1 were used. The production of ethanol from paper sludge for ethanol sales (scenario 1) resulted in higher IRR and NPV values, as well as shorter payback periods, compared to replacement of LPG at the paper mill (scenarios 2 and 3). At an assumed enzyme cost of $ 0.90 gal-1 (R 2.01 litre-1), IRR values of 11%, 22% and 30% were obtained at paper sludge feed rates of 15, 30 and 50 t d-1. A sensitivity analysis performed on the total capital investment and enzyme cost revealed that the SSF process is only economically viable at a paper sludge feed rate of 50 t d-1 irrespective of the variation in capital investment. For the SSF process to be economically viable the enzyme costs must be lower than $ 0.70 gal-1 (R 1.56 litre-1) and $ 1.20 gal-1 (R 2.68 litre-1) for paper sludge feed rates of 30 and 50 t d-1 respectively. The SSF process at a paper sludge feed rate of 15 t d-1 was not economically viable even assuming a zero enzyme cost. A Monte Carlo simulation revealed that the SSF process is economically viable at a paper sludge feed rate of 50 t d-1 as a mean IRR value of 32% were obtained with a probability of 26% to attain an IRR value lower than 25%. The SSF process at lower paper sludge loadings is not economically viable as probabilities of 70% and 95% were obtained to attain IRR values lower than 25% at paper sludge feed rates of 30 and 15 t d-1 respectively. From this study it can be concluded that paper sludge is an excellent feedstock for ethanol production for the sales of ethanol at a paper sludge feed rate in excess of 50 t d-1 with the added environmental benefit of reducing GHG emissions by 42.5%. / AFRIKAANSE OPSOMMING: Aangesien dat brandstof vir vervoer en energie meestal vanaf fossiel afgeleide bronne kom, is daar onlangs ʼn groter fokus op bio-brandstowwe as gevolg van die impak van fossiel afgeleide brandstowwe op die omgewing en 'n verhoogde aanvraag na energie wêreldwyd, gepaardgaande met die uitputting van fossielbrandstof-reserwes. Papier slyk geproduseer deur papier meule is hoog in lignosellulose en verteenwoordig 'n grootliks onontginde grondstof vir etanol produksie. Die doel van die studie was om vas te stel wat die samestelling, fermenteerbaarheid, optimale papier slyk en ensiem ladings is vir die vervaardiging van etanol uit papier slyk. Die inligting was gebruik om 'n model van die proses in Aspen Plus® te ontwikkel. Die massa-en energiebalanse wat verkry is van die Aspen Plus® model was gebruik om toerusting spesifikasies te ontwikkel wat gebruik was om toerusting kostes te bereken. ‘n Tegno-ekonomiese model is ontwikkel om die ekonomiese lewensvatbaarheid van die gelyktydige versuikering en fermentasie proses “SSF” wat gebruik maak van papier slyk as grondstof te assesseer. Nege papier slyk monsters verkry vanaf Nampak Tissue (Pty) Ltd. is geëvalueer in terme van etanol produksie. Die monsters wat die hoogste en laagste etanol konsentrasies opgelewer het, is geselekteer vir optimalisering omdat dit toegelaat het vir die vasstelling van etanol konsentrasies en opbrengste, uitgedruk as persentasie van die teoretiese maksimum, wat verwag kan word in industrie. Reaksie oppervlak metodologie “RSM” is gebruik om wiskundige modelle te ontwikkel om die impak van papier slyk lading en sellulase dosis op etanol produksie en etanol opbrengs te assesseer. Die RSM is aangevul met 'n multi effek optimiserings benadering wat 'n wenslikheid funksie inkorporeer om die optimale papier slyk lading en sellulase dosis in gevoerde-enkellading SSF kulture te bepaal. Die multi effek optimalisering het getoon dat 'n optimale papier slyk lading van 21% (w/w) en 'n sellulase dosis van 14.5 FPU g-1 gebruik moet word, ongeag van die papier slyk monster. Die feit dat die optimale ensiem dosis en papier slyk lading dieselfde is ongeag die papier slyk monster, is aantreklik aangesien die SSF proses meer doeltreffend beheer kan word omdat proses veranderinge nie nodig is om die proses te optimaliseer nie. By die optimale papier slyk lading en sellulase dosis kan 'n minimum etanol konsentrasie van 47.36 g l-1 (84,69% van die teoretiese maksimum) verwag word ongeag van die papier slyk wat gebruik word. 'n Ekonomiese evaluasie is gedoen om vas te stel of etanol produksie vanaf papier slyk met behulp van SSF ekonomies lewensvatbaar is. Drie moontlikhede is ondersoek. In die eerste moontlikheid is die inkomste bereken vanaf etanol verkope gekoppel aan die basiese brandstofprys, terwyl in die tweede en derde moontlikhede, LPG by die papier meul vervang is met anhidriese en 95% etanol onderskeidelik. In al die gevalle was daar gebruik gemaak van papier slyk voer tempo’s van 15, 30 en 50 t d-1. Die produksie van etanol uit papier slyk vir verkope (moontlikheid 1) het gelei tot hoër IRR en die NPV waardes, sowel as korter terugverdien tydperke, in vergelyking met die vervanging van LPG by die papier meul (moontlikhede 2 en 3). Met ʼn ensiem koste van $ 0.90 gal-1 (R 2.01 litre-1) is IRR-waardes van 11%, 22% en 30% verkry teen papier slyk voer tempo’s van 15, 30 en 50 t d-1 onderskeidelik. 'n Sensitiwiteitsanalise uitgevoer op die totale kapitale belegging en ensiem koste het aan die lig gebring dat 'n SSF proses slegs ekonomies lewensvatbaar is op 'n papier slyk voer tempo van 50 t d-1 ongeag van die variasie in die kapitale belegging. Vir die SSF proses om ekonomies lewensvatbaar te wees, moet die ensiem kostes laer wees as $ 0.70 gal-1 (R 1.56 liter-1) en $ 1.20 gal-1 (R 2.68 liter-1) vir papier slyk voer tempo’s van onderskeidelik 30 en 50 t d-1. Die SSF proses was op 'n papier slyk voer tempo van 15 t d-1 nie ekonomies lewensvatbaar nie, selfs teen 'n ensiem koste van nul. 'n Monte Carlo-simulasie het getoon dat die SSF proses ekonomies lewensvatbaar is met 'n papier slyk voer tempo van 50 t d-1 omdat 'n gemiddelde IRR-waarde van 32% verkry is met 'n waarskynlikheid van 26% om 'n IRR-waarde laer as 25% te verkry. Die SSF proses teen papier slyk voer tempo’s van 30 en 15 t d-1 is nie ekonomies lewensvatbaar nie omdat waarskynlikhede van 70% en 95% onderskeidelik verkry is om IRR-waardes laer as 25% te kry. Daar kan van die studie afgelei word dat papier slyk 'n uitstekende grondstof is vir die produksie van etanol mits 'n papier slyk voer tempo van meer as 50 t d-1 bereik kan word. Die produksie van etanol vanaf papier slyk het die bykomende voordeel dat kweekhuis gasse (GHG) met 42.5% verminder word.

O uso de sub-produtos oriundos do processo de produção de álcool etílico na alimentação animal, pode ser uma excelente alternativa no aumento da eficiência alimentar das rações, reduzindo o custo do cultivo na aqüicultura. Este estudo teve como objetivo avaliar os efeitos da suplementação de dois níveis (2,5 e 5,0%) de levedura íntegra desidratada - LI (Saccharomyces cerevisiae) e seus derivados, autolisado – LA e parede celular - PC, em dietas para juvenis de pacu (Piaractus mesopotamicus). Foram avaliados parâmetros de desempenho produtivo, composição corporal e plasmática, índices hepato e víscero somáticos, e determinados os coeficientes dos disgestibilidade dos ingredientes-teste por meio das técnicas "in vivo" e "in vitro". No teste de desempenho utilizou-se delineamento inteiramente casualizado em esquema fatorial 3 x 2 +1, correspondente a três ingredientes-teste, dois níveis e mais uma dieta controle - C (sem levedura ou derivados), empregando-se 5 repetições com peixes cada, totalizando 350 juvenis de pacu (12,0 g e 8,5 cm). Foram formuladas 7 dietas isoprotéicas (26% PD kg-1 de ração ) e isoenergéticas (3.100 kcal ED kg-1 ração), contendo os níveis crescentes de cada ingrediente (LI2,5; LI5,0; LA2,5; LA5,0; PC2,5 e PC5,0). As dietas foram fornecidas ad libitum, duas vezes ao dia durante 90 dias, monitorando-se diariamente os parâmetros químicos da água. Os índices zootécnicos avaliados foram: consumo de ração (CR), conversão alimentar (CA), sobrevivência (S), taxas de crescimento específico (TCE), taxa de eficiência protéica (TEP) e ganho de peso individual total (GPA), além dos índices víscero (IVS) e hepato (IHS) somáticos, composição corporal e plasmática (uréia, ácido úrico, glicose, proteína e cortisol) verificados ao final do período de alimentação. Para determinação dos coeficientes de digestibilidade aparente dos ingredientes-teste foi utilizado o marcador inerte óxido de crômio. Adicionalmente foram determinados os valores digestíveis da proteína dos ingredientes-teste, por meio da técnica "in vitro". Não houve ocorrência de mortalidade em nenhuma das unidades experimentais. De modo geral, a utilização da levedura e derivados acarretou melhora da eficiência alimentar e da utilização protéica. Entretanto, apenas PC5,0 e LA2,5 tiveram efeito positivo significativo na TEP e na CA respectivamente, em relação ao tratamento controle. A composição de carcaça e níveis plasmáticos não foram afetados pela suplementação dos ingredientes-teste para o pacu. Os coeficientes de digestibilidade aparente obtidos para LI e PC para a proteína e energia foram menores (P<0,05) que os coeficientes da LA. O emprego da metodologia "in vitro" pode ser utilizado como alternativa na determinação da digestibilidade da fração protéica dos alimentos para o pacu. Entretanto, em função das características do ingrediente utilizado, os valores podem ser superestimados, em comparação aos valores "in vivo". / The use of by-products from ethyl alcohol production in the animal nutrition, can be a excellent alternative for the increase of feed efficiency, reducing the costs of production in aquaculture. This study was conducted to evaluate the inclusion of two levels (2.5 e 5.0%) of dried yeast - LI (Saccharomyces cerevisiae) and its by-products, disrupted yeast cells - LA and yeast cell wall - PC, in diets for juveniles of pacu (Piaractus mesopotamicus). Productive pattern performance, body and plasmatic composition, hepato and viscera somatic indexes such as determination of digestibility coefficient of the test ingredients by means of "in vivo" and "in vitro" techniques were evaluated. Performance test was conducted with 350 pacu juveniles (12.0 g and 8.5 cm), using delineation completely randomized in a factorial (3 X 2+ 1), corresponding to three test ingredients, two levels and a control diet – C (without yeast or by-products), with five replication with ten fishes each. Seven isoproteic (26 % DP) and isoenergetic (3,100 kcal DE) diets were formulated containing increasing levels of each ingredient (LI2.5; LI5.0; LA2.5; LA5.0; PC2.5 and PC5.0). The diets were supplied for 90 days, "ad libitum" twice a day and the chemical parameters of the water were daily monitored. The performance parameters evaluated were: feed intake (CR), feed convertion (CA), survival, specific growth rate (TCE), proteic efficiency rate (TEP), individual weight gain (GPA), viscero (IVS) and hepato (IIHS) somatic indexes, body and plasmatic composition (urea, uric acid, glucose, plasmatic protein and cortisol) verified at the end of feeding. To determine apparent digestibility coefficients of the test ingredients it was used the chromic oxide inert marker. In addition, digestive values of the test ingredients protein were determined by means of "in vitro" technique. During the experiment no mortality was observed. In general, using yeast and by-products increased feed efficiency and proteic use. However, only PC5.0 and LA2.5 were observed positive significant effects (P<0.05) for TEP and CA respectively, comparing to the control diet. Carcass composition and plasmatic levels were not affected by of the test ingredients supplementation for pacu. The apparent digestibility coefficients obtained for LI and PC for protein and energy were lower (P<0.05) than LA coefficients. The "in vitro" methodology can be used as an alternative to determine the digestibility of proteic portion of pacu food. However, according to the characteristics of the ingredient used, values can be superestimated, comparing to "in vivo" values.

Thesis (MTech (Horticulture))--Cape Peninsula University of Technology, 2016. / Waste management in winery and distillery industries faces numerous disposal challenges as large volumes of both liquid and solid waste by-products are generated yearly during cellar practices. Composting has been suggested a feasible option to beneficiate solid organic waste. This incentivized the quest for efficient composting protocols to be put in place. The objective of this study was to experiment with different composting strategies for spent winery solid waste. Compost materials consisting of chopped pruning grape stalks, skins, seed and spent wine filter material consisting of a mixture of organic and inorganic expend ingredients were mixed in compost heaps. The filter material component varied (in percentage) among five treatments: T1 (40%) lined, T2 (20%) lined, T3 (0%) lined, T4 (40%) grinded material, lined and T5 (40%) unlined. Composting was allowed to proceed in open air over 12 months, from autumn to summer. Indicators such as temperature, moisture, enzyme activities, microbial counts, pH, and C/N ratio, were recorded. Generally, season (df =3, 16, P < 0.05) had significant effects (df =1, 3, P < 0.05) on heap temperature and moisture in all treatments. Similarly, microorganisms (actinobacteria and heterotrophs) varied significantly in all treatments in response to seasonal change (df = 3, 16; P < 0.05). Enzyme activities fluctuated in accordance with seasonal factors and compost maturity stages, with phosphatases, esterases, amino-peptidases, proteases and glycosyl-hydrolases being most prominent. Compared to treatments T2 and T3, compost treatments with higher percentage waste filter materials (T1, T4 and T5) had higher N (16100-21300 mg/kg), P (1500-2300 mg/kg), K (19800-28200 mg/kg), neutral pH, and lower C/N ratios (13:1-10:1), which were also comparable with commercially produced composts. Filter materials therefore, appears to be a vital ingredient for composting of winery solid waste.

Este estudo teve como objetivo avaliar os efeitos da inclusão de dois níveis (2,5 e 5%) de levedura íntegra desidratada (Saccharomyces cerevisiae) e seus derivados, parede celular de levedura (MOS) e autolisado de levedura, em dietas para juvenis de pintado (Pseudoplatystoma coruscans), sobre os parâmetros de desempenho produtivo, composição corporal, índices hepatossomático e víscerossomático e digestibilidade aparente dos ingredientes-teste. Foram utilizados 336 juvenis de pintado, já treinados a comer ração seca, com peso médio aproximado de 17 g distribuídos em um Delineamento Inteiramente Casualizado em esquema fatorial 3 x 2 + 1 correspondente aos três ingredientes-teste utilizados em duas diferentes porcentagens de fornecimento e tratamento testemunha (sem levedura ou derivados), utilizando-se "hapas" com capacidade para 60 litros, com 12 peixes por unidade. Foram formuladas 7 dietas isoprotéicas (45% PB) e isoenergéticas (4200 kcal EB/kg), contendo levedura íntegra desidratada, levedura autolisada e parede celular de levedura (2,5% e 5,0%). As dietas foram fornecidas durante 64 dias, 2 vezes ao dia e ad libitum. Parâmetros físico-químicos da água como oxigênio dissolvido, temperatura e pH foram monitorados diariamente. Os parâmetros de desempenho avaliados foram taxa de crescimento específico, conversão alimentar aparente, sobrevivência e consumo de ração. As análises de composição corporal, índice viscerossomático, índice hepatossomático foram realizados após o período experimental. O ensaio de digestibilidade foi conduzido para determinar o coeficiente de digestibilidade aparente dos ingredientes-teste, utilizando-se rações com marcador inerte oxido de crômio. A levedura e seus derivados tiveram efeito sobre a composição de carcaça, TCE%, SO% e CR(g), níveis plasmáticos de proteína e ácido úrico. O tratamento sem levedura apresentou a menor taxa de sobrevivência, podendo-se inferir que a levedura e seus derivados podem melhorar o sistema imunológico dos pintados. Os coeficientes de digestibilidade aparente obtidos para a proteína da levedura íntegra, parede celular e levedura autolisada foram respectivamente de 71,54%, 77,45% e 28,48%. Conclui-se, portanto, que a levedura e seus derivados podem ser utilizados na nutrição de pintados em até 5% como pró-nutrientes, promovendo melhor desempenho e sobrevivência, sem prejuízo ao metabolismo dos animais. / The goal of this study is to appraise the inclusion of two levels (2,5 and 5%) of dried yeast (Saccharomyces cerevisiae) and its by-products, yeast cell wall (MOS) and disrupted yeast cells, in diets for juveniles of pintado (Pseudoplatystoma coruscans), based on its productive pattern performance, body composition, hepatosomatic and viscera somatic and digestibility index that appears on the test ingredients. It was used 336 of juvenile of pintado, already trained to eat dried portion, with medium average weight of 17 g distributed in a totally randomized 3 x 2 + 1 factorial design, corresponding to three test ingredients, used in two different percentages supplied in testimony treatment (without yeasts or by-products), Using cages with capacity of 60 lt., with 12 fishes per unit. It was developed 7 isonitrogenous diets (45% CP) and isoenergetic diets (4200 kcal EB/kg), containing dried yeast, disrupted yeast cells and yeast cell wall (2,5% e 5,0%). The diet was supplied during 64 days, 2 times per day and ad libitum. The physical-chemical analysis patterns of water as dissolved oxygen, temperature and pH was daily monitored. The performance patterns appraised were based on specific growing rate, apparent feed conversion, survival and consumption of portion. The analysis of body composition index of viscera somatic, hepatosomatic were realized after the experimental period. The digestibility trial was conducted to determine the apparent digestibility coefficients (ADC) for test ingredients, using diets with chromic oxide as inert marker. The yeast and its by-products had effect over carcass composition, Specific growth rate (SGR%), Survival (S%) and Feed Intake (g), protein plasmatic levels and uric acid. The treatment without yeast presented the lower tax of survival, being able to indicates that the yeast and its by-products can improve the pintados immune system. The ADC obtained to yeast protein, yeast cell wall and disrupted yeast cells were 71,54%, 77,45% and 28,48%. In summary, the yeast and its by-products can be used in the pintados nutrition until 5% as feed additive, promoting better performance and survival, without damage the animals metabolism.

This project focuses on two important topics which may pose hazards to human health. Firstly, drinking water disinfection by-products (DBPs), which are generated by the chemical disinfection of water have been investigated. What has not been shown is the effect of DBPs in human germ cells as well as somatic cells and whether oxidative stress is involved in the mechanism of genotoxic action. Three different DBPs (halo acetic acids: HAAs), together with the antioxidants – catalase and butylated hydroxyanisole (BHA), were investigated in peripheral blood cells and sperm from healthy individuals using the Comet assay and lymphocytes only using the micronucleus assay. Secondly, nanoparticles of the non-steroidal anti-inflammatory drugs (NSAIDs), aspirin and ibuprofen, have been investigated in patients with respiratory diseases, in the micronucleus assay and the Comet repair assay. NSAIDs inhibit cyclooxygenase enzyme activity, which plays part in tumour progression. In the Comet assay, BHA and catalase were able to reduce DNA damage in both cell types compared to HAAs alone. Similarly, in the micronucleus assay, micronuclei were reduced with the antioxidants, suggesting oxygen radical involvement in both assays. With the NSAIDs, reductions were seen for DNA damage in the micronucleus assay with aspirin and ibuprofen nanoparticles compared to their bulk forms. Using the Comet repair assay, aspirin and ibuprofen nanoparticles aided repair of DNA to a greater extent than their bulk counterparts, which in turn showed better repair compared to samples repaired without NSAIDs. These observations show the importance of DBPs and NSAIDs in genotoxic public health issues.

This study examines the waste of cotton gins as a potential alternative energy source, on account of its heat content, availability, and low emission rates. To confirm that this potential energy source meets minimum industrial fuel standards, this research has carried out an investigation of some important physical characteristics and toxic element analysis of cotton gin waste. Using cotton gin waste as fuel is an attractive solution to the problems of disposing of a surplus agricultural waste as well as supplementing fuel must meet both environmental emission standards and industrial fuel standards, the physical and chemical characteristics of cotton gin waste and its toxic element concentrations are important for its objective evaluation as a fuel. Constituent components, moisture contents, and ash contents of four separate parts of cotton gin waste were determined and evaluated closely following the American Society for Testing and Materials (ASTM) test methods. The three most toxic heavy metals, Arsenic (As), Chromium (Cr), and Lead (Pb), chosen for quantitative analysis were determined by using an inductively coupled plasma atomic emission spectrometry and a microwave oven sample digestion method.

Road traffic dominates in domestic Swedish transportation and is highly dependent on fossil fuels, petrol and diesel. Currently, the use of renewable fuels in transportation accounts for less than 6% of the total energy use in transport. The demand for bioethanol to fuel transportation is growing and cannot be met through current domestic production alone. Lignocellulosic ethanol derived from agricultural crop residues may be a feasible alternative source of ethanol for securing a consistent regional fuel supply in Swedish climatic conditions.  This licentiate thesis focuses on regional transport fuel supply by considering local small-scale ethanol production from straw. It presents the results of investigations of regional transport fuel supply with respect to minimising regional CO2 emissions, cost estimates for transport fuel supply, and the availability of lignocellulosic resources for small-scale ethanol production. Regional transport fuel demand between the present and 2020 is also estimated. The results presented here show that significant bioethanol can be produced from the straw and Salix available in the studied regions and that this is sufficient to meet the regions’ current ethanol fuel demand.  A cost optimisation model for regional transport fuel supply is developed and applied for two cases in one study region, one when the ethanol production plant is integrated with an existing CHP plant (polygeneration), and one with a standalone ethanol production plant. The results of the optimisation model show that in both cases the changes in ethanol production costs have the biggest influence on the cost of supplying the regional passenger car fleet with transport fuel, followed by the petrol price and straw production costs.  By integrating the ethanol production process with a CHP plant, the costs of supplying regional passenger car fleet with transport fuel can be reduced by up to a third. Moreover, replacing petrol fuel with ethanol can cut regional CO2 emissions from transportation by half.

This work reports the results of a systematic study of the factors that affect the bridging behaviour of bagasse. It shows that traditional bulk solids theory is inappropriate for predicting bagasse flow mainly because of the impossibility of obtaining a reliable measure of internal friction. It demonstrates the significant influence of fibre length and moisture content on its handling charateristics. Correlations of pertinent bulk properties such as compactibility, tensile strength, surface friction and translation of vertical into horizontal pressure have been developed. These were derived as a result of measurements in equipment that was designed for the purpose. Finally, an empirical model utilising these correlations is proposed by which the likelihood of bridge formation in any piece of bagasse handling equipment can be determined. The validity of the model is assessed by comparison with bridging tests that were performed under controlled conditions. / Thesis (Ph.D.)-University of Natal, 1996