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abstract: Smoke entering a flight deck cabin has been an issue for commercial aircraft for many years. The issue for a flight crew is how to mitigate the smoke so that they can safely fly the aircraft. For this thesis, the feasibility of having a Negative Pressure System that utilizes the cabin altitude pressure and outside altitude pressure to remove smoke from a flight deck was studied. Existing procedures for flight crews call for a descent down to a safe level for depressurizing the aircraft before taking further action. This process takes crucial time that is critical to the flight crew's ability to keep aware of the situation. This process involves a flight crews coordination and fast thinking to manually take control of the aircraft; which has become increasing more difficult due to the advancements in aircraft automation. Unfortunately this is the only accepted procedure that is used by a flight crew. Other products merely displace the smoke. This displacement is after the time it takes for the flight crew to set up the smoke displacement unit with no guarantee that a flight crew will be able to see or use all of the aircraft's controls. The Negative Pressure System will work automatically and not only use similar components already found on the aircraft, but work in conjunction with the smoke detection system and pressurization system so smoke removal can begin without having to descend down to a lower altitude. In order for this system to work correctly many factors must be taken into consideration. The size of a flight deck varies from aircraft to aircraft, therefore the ability for the system to efficiently remove smoke from an aircraft is taken into consideration. For the system to be feasible on an aircraft the cost and weight must be taken into consideration as the added fuel consumption due to weight of the system may be the limiting factor for installing such a system on commercial aircraft. / Dissertation/Thesis / M.S.Tech Mechanical Engineering 2013

The presence of organic contaminants in water has caused great concern over their potential adverse health impact on humans and animals. Organic contaminants found in water are both naturally occurring and synthetic. Various chemical and physical water treatment processes are being used to remove organic contaminants. Conventional water treatment methods include the utilization of activated carbon for the removal of organic contaminants. It is generally conceded that activated carbon owes its adsorptive properties primarily to its large surface area, as well as to its pore size. Although activated carbon is nonselective against most of the water contaminants, it does not remove the concentration of organic contaminants to acceptable levels i.e. ppb. Moreover, activated carbon also absorbs moisture from the air and as a result loses its absorptive effectiveness. For this reason attention has been being given to alternative methods for water treatment especially for the removal of organic pollutants. In this study, cyclodextrin polymers that were water insoluble were synthesized and tested for their ability to remove organic species in water. Cyclodextrins (CDs) and their corresponding derivatives have been used in a wide range of applications including pharmaceutical and pesticide removal and catalysis. Cyclodextrins are cyclic oligosaccharides derived from enzyme degradation of starch. They are known as molecular hosts capable of including of forming inclusion complexes, with a degree of selectivity, with a range of guest molecules via a noncovalent interaction in their hydrophobic cavities. Although the interaction between cyclodextrin and an organic molecule is the basis for absorption or separation of various organic agents, the solubility of cyclodextrin in water and organic solvents impose limitations to the application of cyclodextrins in water treatment. Therefore, polymerizing a cyclodextrin monomer with an excess of a bifunctional linker produces an insoluble polymer which can form inclusion complexes with guest molecules. In this project, the synthesis of a number of cyclodextrin polymers was performed by reacting cyclodextrin with bifunctional linkers. / Dr. B. B. Mamba Dr. R. W. M. Krause Dr. T. J. Malefetse

As one of the most abundant elements on earth, iron is nearly always present in metal concentrates. This is specifically true for zinc sulphide concentrates, which can contain up to 18% iron (marmatite). Today more than half of these concentrates are treated in hydrometallurgical- or combined hydrometallurgical¬pyrometallurgical circuits. In hydrometallurgical circuits, iron is solubilised (either in a roast-Ieach-, a direct leach- or bacterial leach circuit) along with zinc and must be removed from the zinc¬rich solution before the electrowinning- or solvent extraction step. Various iron removal processes were developed to address the iron problem in hydrometallurgical circuits. The better known of these include the jarosite-, goethite- and hematite processes also used in the zinc industry. Zincor (Zinc Corporation of South Africa) patented an iron removal process (Zincor Process), which was generally considered to be very similar to the so-called "para-goethite" iron removal process used only in two other zinc smelters notably Porto Vesme (Italy) and Pasminco Hobart (Tasmania). However, since the Zincor Process was patented in 1976, various changes have been made such as a change from a batch parallel to a continuous series process, a change in precipitation pH-profile and the introduction of a pH controlled acid wash in the second tank. The introduction of a weak acid leach step and vacuum belt filters at Zincor's residue treatment plant in the near future and an iron removal process that is not clearly understood, necessitated this further study of the Zincor iron removal process. The study has been conducted in three parts. The first part of the study has focused on the characterisation of the Zincor iron residue and the Zincor process. The second part of the study has been concerned with the definition of an optimum operating window in terms of the filterability of the residue and the third part investigated the use of neutralisation reagents other than zinc calcine to control the pH during iron precipitation. The distribution of iron in the Zincor iron precipitate, which usually contains between 35% and 40% iron, has been found to be as follows: approximately 45% as schwertmannite, 5% as ferrihydrite, 20% as jarosites, 25% as franklinite, trace amounts of pyrite as well as 5% of an unknown phase. This confirmed that goethite is not present in the Zincor iron residue and that iron is mainly removed in the form of amorphous intermediate iron phases such as schwertmannite and ferrihydrite. Of these two phases, schwertmannite was the least expected as most work up until now were done on samples taken from natural environments. The following description of the conditions that promote iron removal, mainly as schwertmannite, is viewed as an expansion of the available literature data, which was gathered at ambient conditions. In terms of the main operating parameters, optimum filterability was achieved under the following conditions: pH of 3.0, temperature as high as possible (70°C) and at least 25 kg/m3 seeding. A retention time of at least 4 hours at a pH of 3.0 and 60°C was required, which decreased by more than 50% at a temperature of 70°C. As these conditions mainly impact on the soluble zinc loss encountered during iron removal, an effort was made to further reduce the insoluble zinc loss, which is the inherent weakness in the Zincor process, and similar processes where zinc calcine is used for pH control, by investigating the use of alternative neutralisation reagents. This study showed that iron can be successfully removed with Ca(OH) 2, a basic zinc sulphate and zinc oxide mixture as well as chemically precipitated CaC03 produced in the paper and pulp industry. Of these alternatives, CaC03 appeared to be the most promising, with filtration rates an order of magnitude higher than the zinc oxide options (calcine and basic zinc sulphate mixture), due to better overall economics than with the use of Ca(OH) 2. Utilisation CaC03 as an alternative neutralisation agent might increase the overall zinc recovery figure at Zincor by up to 1.5%. Based on the findings, it can be concluded that the Zincor process in its current form has a very distinct character compared to what was historically considered to be the very similar patented para-goethite iron removal process, as practiced at the Porto Vesme and the Pasminco Hobart hydrometallurgical zinc plants. / Dissertation (MEng (Metallurgical Engineering))--University of Pretoria, 2006. / Materials Science and Metallurgical Engineering / unrestricted

Batch tests were performed to evaluate the relative performance of four B.C. coals (Hat Creek Oxidised, Kaiser-stock pile refuse, Kaiser-special plant feed and Cominco Ash) in removing heavy metals copper, lead, zinc and mercury from filtered primary sewage treatment plant effluent. Emphasis was placed on metal concentrations of 10 mg/l and less. Hat Creek coal was found to be much superior to the other three and its efficiency is comparable to that of Darco activated carbon 12 x 20. Hat Creek and Kaiser-stock pile refuse coals were further used in column tests to evaluate the relative performance of these coals in removing copper, lead and zinc under dynamic conditions. Again emphasis was placed on influent metal concentrations of 10 mg/1 and less and once more the performance of Hat Creek coal was much superior to that of Kaiser coal. Tests with activated carbon indicate Hat Creek coal to be a close competitor for use in advanced waste treatment for heavy metal removal. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Water pollution due to heavy metals can be hazardous to both the environment and human health. The aim of this research is to provide a low-cost alternative for lead remediation. Biochar was produced from the fast pyrolysis of Douglas fir (DBC). Magnetic biochar (MDBC) was synthesized by mixing aqueous biochar suspensions with an aqueous Fe3+/Fe2+ solution. In chapter I, an overview of lead as an emergent contaminant is given. Different biochar production techniques have been discussed along with different mechanism of adsorption of lead onto biochar. Chapter II is a study of adsorption of lead on DBC and MDBC under different experimental conditions. The main aim of this research is to study the effect of water hardness on adsorption capacity. Three levels of water hardness were employed. Sorption performances were evaluated using Langmuir and Freundlich adsorption isotherms. DBC and MDBC were also successfully applied for lead removal from natural water samples. In chapter III, future projects focused on studying the effects of matrix chemicals found in natural waters on the heavy metal ion adsorption properties of biochar are discussed.

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Sludge digestion has gained importance in recent year because of increasing interest in energy recovery and public concern over the safety of land applied biosolids. Many new alternatives are being researched for reducing excess sludge production and for more energy production. With an increase in solids destruction, the nutrients that are contained in sludge especially nitrogen, are released to solution and can be recycled as part of filtrate or centrate stream. Nitrogen has gained importance because it has adverse effects on ecosystem's as well as human health. NH₄⁺, NO₂⁻, NO₃⁻-, and organic nitrogen are the different forms of nitrogen found in wastewater. While ammonia is toxic to aquatic life, any form of nitrogen can be utilized by cyanobacteria and result in eutrophication. NO₂/NO₃, if consumed by infants through water, can affect the oxygen uptake capability. Hence, removal of nitrogen from wastewater stream before discharging is important. The main purpose of this study was to evaluate the performance of the Cambi process, a thermophylic hydrolysis process used as a pre-treatment step prior to anaerobic digestion. Thermal hydrolysis, as a pre-treatment to anaerobic digestion increases the biological degradation of organic volatile solids and biogas production. The thermal hydrolysis process destroys pathogens and hydrolysis makes the sludge readily available for digestion, while at the same time facilitating a higher degree of separation of solid and liquid phases after digestion. Experiments were conducted in three phases for anaerobic digestion using the Cambi process as pre-treatment. The phases of study includes comparison of two temperatures for thermal hydrolysis (Cambi 150°C and Cambi 170°C), comparison of two solid retention times in anaerobic digestion (15 Day and 20 Day) and comparison of two mesophilic temperatures in anaerobic digestion (37°C and 42°C). Different experimental analyses were conducted for each phase, such as pH, bio-gas production, COD removal, VS destruction, nitrogen removal, odor and dewatering characteristics and the results are compared among all the phases. The second part of the study deals with aerobic digestion of anaerobically digested sludge for effective nitrogen removal and additional VS destruction, COD removal. An aerobic digester is operated downstream to anaerobic digester and is operated with aerobic/anoxic phase for nitrification and de-nitrification. The aerobic/anoxic phases are operated in time cycles which included 40minutes/20minutes, 20minutes/20minutes, full aeration, 10minutes/30minutes, and 12minutes/12minutes. Different time cycles are experimented and aerobic digester is optimized for effective nitrogen removal. 12minutes aerobic and 12minutes anoxic phase gave better nitrogen removal compared to all the cycles. Over all the aerobic digester gave about 92% ammonia removal, 70% VS destruction and 70% COD removal. The oxygen uptake rates (OUR's) in the aerobic digester are measured corresponding to maximum nitrogen removal. The OUR's are found to be close to 60 mg/L during maximum nitrogen removal. The effluent from both anaerobic digester and aerobic digester was collected and analyzed for dewatering capability, cake solids concentration and odor potential. / Master of Science