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Garden refuse has been seen to constitute a significant proportion of the total waste stream received at landfills in the eThekwini Municipal Area (EMA). With the growing demand for conserving “precious landfill airspace” as a result of limited availability of land for new landfill development, there is a shift in the mindsets of landfill operators to adopt alternative methods of treatment other than the traditional way of landfilling. As a result composting of green waste stream was seen as the most appropriate treatment solution as not only would there be a direct landfill airspace saving but the added environmental, economical and social sustainable benefits to the city. The first South African Waste Summit saw the signing of the Polokwane Declaration i.e. “Reduce waste generation and disposal by 50% and 25% respectively by 2012 and develop a plan for ZERO WASTE by 2022”. Hence, the push for composting to try and achieve waste reduction to landfills. The Dome Aeration Technology (DAT) is an advanced treatment option for aerobic biological degradation of garden refuse (Mollekopf et al, 2002, Trois and Polster, 2006). The originality of the DAT system is the use of passive aeration brought about by thermal driven advection through open windrows which is induced by thermal differences between the composting material and the ambient atmosphere (Polster, 2003). Previous work on organic waste composting using the DAT on a small scale showed that good quality compost was attainable within 6 weeks of composting (Moodley 2005). This study offers comparative performances between DAT system and Traditional Turned Windrows (TTW) in composting garden refuse and recommending the most appropriate system for integration into existing landfill operations. Full scale windrows were constructed for each system at the Bisasar Road Landfill Site in Durban, Kwa-Zulu Natal to evaluate the influence of climate, quality of compost, operational requirements and feasibility. The process monitoring for the DAT windrow showed that temperatures reached thermophilic ranges within a week of composting which confirms that of the German studies. Waste characterisation of both input and output materials are discussed for both systems with recommendations on the most practical and appropriate system applicable to that of an operational landfill are drawn. The study further concludes with potential uses of the composted garden refuse within landfill sites and its contribution to “closed loop” landfilling yet within an integrated waste management plan. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

The objective of this thesis was to design a canister for the disposal of spent nuclear fuel and other high-level waste in deep borehole repositories using currently available and proven oil, gas, and geothermal drilling technology. The canister is suitable for disposal of various waste forms, such as fuel assemblies and vitrified waste. The design addresses real and perceived hazards of transporting and placing high-level waste, in the form of spent reactor fuel, into a deep igneous rock environment with particular emphasis on thermal performance. The proposed boreholes are 3 to 5 km deep, in igneous rock such as granite. The rock must be in a geologically stable area from a volcanic and tectonic standpoint, and it should have low permeability, as shown in recent data taken from a Russian deep borehole. Although deep granite should remain dry, water in flooded boreholes is expected to be reducing, but potentially corrosive to steel. However, the granite and plug are the containment barrier, not the canister itself. The canisters use standard oil drilling casings. The inner diameter is 315.32mm in order to accommodate a PWR assembly with a width of 214mm. At five meters tall, each canister holds one PWR assembly. The canister thickness is 12.19mm, with an outer diameter of 339.7mm. A liner can extend to the bottom of the emplacement zone to aid in retrievability. The liner has an outer diameter of 406.4mm and a thickness of 9.52mm. The standard drill bit used with a liner of this size has an outer diameter of 444.5mm. / Contract number: N62271-97-6-0026. / US Navy (USN) author.

Dissertation submitted in compliance with the requirements for the Master's Degree in Technology: Biotechnology, Durban Insititute of Technology, 2003. / Stimulated by the findings of international researchers, that the sulfate-reducing microorganism Desulfovibrio desulfuricans could be incriminated in the process of mercury bio-methylation, it was decided to test this hypothesis on sediments from selected areas of Durban Bay where elevated levels of the bio-hazardous heavy metal had previously been detected. The Environmentek Division of the Council for Scientific and Industrial Research (Durban) is involved in an ongoing chemical assessment of heavy metal contamination (including levels of mercury) in the sediments of this estuary, but nothing is currently understood about the form in which mercury exists or the biological processes that could be determining its fate. The purpose of this project was to attempt to answer some of these questions. The study involved attempting to isolate, identify and quantify microorganisms of the species Desulfovibrio desulfuricans, Escherichia coli and Clostridium perfringens in one hundred and eighty sediment samples taken from three designated sites in the bay. Each sample was additionally analysed for total and methyl mercury and sulfate content, as well as a number of physical parameters. Based on the outcome of the initial survey, it was envisaged that further laboratory experimentation would be conducted to determine whether or not isolates were responsible for the production of the highly toxic organic mercury and whether this process was occurring in situ in the sediments. The findings of this project were contrary to what had been expected. Total mercury concentrations (apart from one instance) did not appear to be appreciably elevated in the areas under study. Similarly, the levels of methyl mercury were fourrd to be either diminished or absent. Numbers of D. desulfuricans were low and not uniformly distributed throughout the sediments. Cl. perfringens was more in evidence, but counts were not perceptibly increased. Sulfate levels were consistently high, indicating significantly impaired rates of sulfate reduction. Difficulty experienced in sub-culturing / M

Anaerobic digestion is a sustainable and economically feasible waste management technology, which lowers the emission of greenhouse gases (GHGs), decreases the soil and water pollution, and reduces the dependence on fossil fuels. The present thesis investigates the anaerobic digestion of waste from food-processing industries, including citrus wastes (CWs) from juice processing and chicken feather from poultry slaughterhouses. Juice processing industries generate 15–25 million tons of citrus wastes every year. Utilization of CWs is not yet resolved, since drying or incineration processes are costly, due to the high moisture content; and biological processes are hindered by its peel oil content, primarily the D-limonene. Anaerobic digestion of untreated CWs consequently results in process failure because of the inhibiting effect of the produced and accumulated VFAs. The current thesis involves the development of a steam explosion pretreatment step. The methane yield increased by 426 % to 0.537 Nm3/kg VS by employing the steam explosion treatment at 150 °C for 20 min, which opened up the compact structure of the CWs and removed 94 % of the D-limonene. The developed process enables a production of 104 m3 methane and 8.4 L limonene from one ton of fresh CWs. Poultry slaughterhouses generate a significant amount of feather every year. Feathers are basically composed of keratin, an extremely strong and resistible structural protein. Methane yield from feather is low, around 0.18 Nm3/kg VS, which corresponds to only one third of the theoretical yield. In the present study, chemical, enzymatic and biological pretreatment methods were investigated to improve the biogas yield of feather waste. Chemical pretreatment with Ca(OH)2 under relatively mild conditions (0.1 g Ca(OH)2/g TSfeather, 100 °C, 30 min) improved the methane yield to 0.40 Nm3/kg VS, corresponding to 80 % of the theoretical yield. However, prior to digestion, the calcium needs to be removed. Enzymatic pretreatment with an alkaline endopeptidase, Savinase®, also increased the methane yield up to 0.40 Nm3/kg VS. Direct enzyme addition to the digester was tested and proved successful, making this process economically more feasible, since no additional pretreatment step is needed. For biological pretreatment, a recombinant Bacillus megaterium strain holding a high keratinase activity was developed. The new strain was able to degrade the feather keratin which resulted in an increase in the methane yield by 122 % during the following anaerobic digestion. / <p>Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 1 juni 2012, klockan 10.00 i KA-salen, Kemigården 4, Göteborg.</p>

Fruits are among the most important commodities in global trading due to its fundamental nutritional values. In 2012, the fruits supply was 115 kg/person/year, however, only 50 % of the fruits reached their consumers and the rest ended up as waste during the long fruit supply chain. The waste from fruits is mostly dumped or burned, creating a serious environmental problem. A more sustainable handling of the waste is therefore highly desirable. One of them is conversion of the fruits wastes into biogas through anaerobic digestion. One challenge with the conversion of fruits wastes into biogas is the presence of antimicrobial compounds in the fruits, which reduce the biogas yield or even cause a total failure of the process. Fruit flavors have been reported to have antimicrobial activity against several microorganisms and being responsible for the defense system in the fruits. However, there is only scarce information about the effect of fruit flavors on anaerobic digesting microbia. The objectives of the present thesis were: 1) to investigate the inhibitory activity of the fruit flavors on anaerobic digestion; 2) to remove the flavor compound by pretreatment; and 3) to protect the cell from the flavor compounds using a membrane bioreactor. The inhibitory activity of the fruit flavors was examined from different groups of flavors by adding a single flavor compound into the batch anaerobic digesting system, at three different concentrations. Among the flavors added, myrcene and octanol were found to exhibit a strong inhibitory activity, with 50 % reduction of the methane production at low concentrations, ca. 0.005–0.05 %. These flavors can be found in oranges, strawberries, grapes, plums, and mangoes. The other flavors tested showed moderate and low inhibitory activity, which might not affect the anaerobic digestion of the fruits wastes. In order to overcome the inhibitory effects of the fruit flavor, two approaches were proposed in this thesis, namely, fruit flavor removal by leaching pretreatment and cell protection from fruit flavor using a membrane bioreactor. Orange peel waste and D-limonene were used as a model of fruit waste and inhibitor, respectively. The leaching pretreatment uses solvent to extract the limonene from the orange peel. The methane yield increased by 356 % from 0.061 Nm3/kg VS to 0.217 Nm3/kg VS, by pretreating the peel using hexane with peel and a hexane ratio of 1:12 at room temperature for 10 min. Alternative to limonene removal, the cells were encased in a hydrophilic membrane, which is impermeable to hydrophobic limonene. This method yielded more than six times higher methane yield, compared to the free cell. At the highest organic loading rate, examined in this work, 3 g VS/L/day, the methane yield of the reactor containing the free cell was only 0.05 Nm3/kg VS, corresponding to 10 % of the theoretical yield, whereas 0.33 Nm3/kg VS methane yield was achieved using a membrane bioreactor corresponding to 75 % of the theoretical yield. / <p>Thesis for the degree of Doctor of Philosophy at the University of Borås to be publicly defended on November 27th 2014, 10.00 a.m. in room E310, University of Borås, Allégatan 1, Borås.</p>

Hides and skins used as a raw material for leather manufacture may be contaminated with various microbial species including potential pathogens. Many bacterial species such as Bacillus, Staphylococcus, Micrococcus and Pseudomonas were isolated from raw hides/skins, and hides/skins at different stages of leather making process. The extreme environmental conditions present during a conventional tanning process due to hazardous chemicals may prevent the growth of bacteria present on hides/skins. On the other hand, partial or total replacement of the hazardous chemicals with non-hazardous chemicals, during a best available technologies (BAT) process, may provide suitable conditions for microbial growth in tannery effluent and hides/skins. Therefore, the aim of the project was to determine the survival and growth of the various bacterial species during the conventional and BAT leather-making processes. The beamhouse and tanning stages were studied, as the majority of the environmental pollution occurs during the early stages of the leather making process. Both the pre-soaking and soaking stages during the conventional and BAT leather-making processes provided suitable conditions for bacterial (Bacillus cereus, Pseudomonas aeruginosa and Staphylococcus spp.) growth and proliferation. The results showed a significant reduction in the number of B. cereus found during the conventional and BAT unhairing processes. Limited B. cereus growth was observed during the subsequent reliming process. Bacillus cereus growth also occurred during the deliming and bating processes (conventional and BAT), followed by a decrease during the conventional and BAT pickling processes. No B. cereus colonies were isolated during the chrome tanning process. Growth of P. aeruginosa was inhibited during both the unhairing and reliming stages of the conventional and BAT leather making processes. A reappearance and recovery of P. aeruginosa in the subsequent deliming and bating (conventional and BAT) processes, indicated that deliming and bating processes may provide suitable growth conditions for P. aeruginosa. On the other hand, both the conventional and BAT pickling processes, and the chrome tanning processes hindered P. aeruginosa growth. Staphylococcus spp. were present throughout the conventional and BAT leather-making processes. A large reduction in the number of Staphylococcus spp. was observed during the unhairing and reliming processes (conventional and BAT). Growth of Staphylococcus spp. occurred during the subsequent deliming, bating, pickling and chrome tanning stages for both the conventional and BAT leather-making processes. The biochemical assays for bacterial identification confirmed the presence of B. cereus, P. aeruginosa and Staphylococcus spp. during the leather processing. The pulsed-field gel electrophoresis (PFGE) method of DNA fingerprinting confirmed that the bacterial species isolated during the leather manufacturing processes were the inoculated B. cereus and P. aeruginosa, and no alteration of the DNA of above-mentioned bacteria occurred during the processing. Overall, the research showed that bacterial species are capable of surviving during both the conventional and BAT leather-manufacturing processes. The bacterial species prefer the environmental conditions during the pre-soaking and soaking processes, while the unhairing and reliming processes did not favour the growth of bacterial species. Bacterial colonies were enumerated during the deliming and bating processes indicating that the unhairing and reliming processes did not cause total destruction of the bacterial cells. Alternatively pickling and chrome tanning processes were found to have suppressed the growth of bacterial colonies.