The use of municipal refuse (RDF) as fuels has received widespread attention for reason of its energy equivalence and the increasing lack of available landfill sites. The principal obstacle to the construction of combustion facilities is that RDF produces toxic compounds, including heavy metals and such organic compounds as PCDD and PCDF. In this study, the emissions of metal and organic compounds were investigated under oxygen deficient and oxygen surplus conditions for the RDF and such high volume contributors as office papers and magazines. The principal metal emissions of the RDF were Al, Ca, K, Si, and Zn. Magazines significantly contribute B, Mg, Mn, Ti emissions, whereas office papers contributed Ti and Zn emissions. The metal emissions were not significantly different between oxygen deficient and oxygen surplus conditions at a temperature of 750��C. The combustion of RDF produced a full range of PCDFs and PCDFs, the source of which was determined to be RDF, papers, and even untreated wood combustion effluents in the parts-per-billion range. In contrast to metal emissions, emission rates were higher under the oxygen surplus condition than for the oxygen deficient condition and PCDD and PCDF emissions were significant in relation to the chloride contents of fuel, rather than by fuel type as was the case for the large volume contributors. With the exception of Hg, Se, S, Sr, and Pb, the metal emissions were largely derived from the particles in the effluent. / Graduation date: 1993 / Text is slanted on original. Best scan available.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Effective combustion of waste fuels requires an understanding of the fuels characteristics. Gaseous and particulate emissions, ash residues and combustion properties are of interest to many; those that produce and sell heating units, utilities interested in using the fuels for power generation, regulatory agencies, municipalities needing to solve a disposal problem, and environmentally conscious people interested in maximum utilization of resources. A study was conducted at Oregon State University to test and evaluate the use of two types of waste: mixed waste paper (MWP) and refuse derived fuel (RDF). Wood biomass (ponderosa pine) was used as a benchmark and also cofired with MWP. Samples collected from the Pacific Northwest were tested for physical, chemical, combustion, and emission characteristics. Raw fuel samples were tested for moisture content and bulk density. The samples were then shredded and pelletized. Pelletized fuels were tested for ultimate and proximate analyses, ash fusion temperature, elemental ash analysis, higher heating value, moisture content, bulk density, and pellet durability. Using an existing biomass combustion facility, the samples were fired to determine the optimum thermodynamic conversion combustion condition for each fuel. Observations were made of physical problems associated with firing of the samples. Combustion products were continuously monitored for temperature and composition with a combustion analyzer. An EPA Method 5 sampling train was used to determine particulate, heavy metals, chloride, fluoride, and sulfate emissions. Leachate testing was performed on the bottom ash residue to determine heavy metal concentrations. Waste fuels provided a challenge for combustion study in a biomass combustion unit. Modifications were required to alleviate high ash content problems. Observations of corrosion and clinkers provided another comparison for fuel evaluation. Comparison of emissions resulting from different fuel types provided good practical information for industrial purposes. Observed trends indicated possible minimization of emissions corresponding to optimum thermodynamic conversion. Cofiring analysis revealed possible increases and decreases of heavy metal emissions for MWP and wood. / Graduation date: 1992

The first part of the thesis presents a study based on the forest biorefinery concept, which involves converting a pulp mill into a multi-purpose biofuels, biomaterials, and biopower production facility in which these products are produced in an environmentally compatible and sustainable manner. A key challenge in this process is the recovery of lignin from process streams such that it can be utilized in a variety of innovative green chemistry processes The first study examines the fundamental chemical structure of LignoBoost derived lignin recovered from Kraft pulping streams using an acid precipitation/washing methodology. Functional group analysis and molecular weight profiles were determined by nuclear magnetic resonance (NMR) and size exclusion chromatography. These findings gave valuable insight into the physical properties and the determining chemical properties of this currently underutilized, renewable bioresource. The second study is based on the future second generation bioethanol production process, where ethanol produced from lignocellulosic materials will bring about the co-production of significant amounts of under-utilized lignin. The study examines the potential of conventional heterogeneous and novel homogeneous catalysts for the selective cleavage of the aryl-O-aryl and aryl-O-aliphatic linkages of ethanol organosolv lignin to convert it from a low grade fuel to potential fuel precursors or other value added chemicals. The experimental data demonstrated that aryl-O-aryl and aryl-O-aliphatic linkages could be cleaved and the hydrogenated lignin had a decrease in oxygen functionality and the formation of products with lower oxygen content. The second part of this thesis reports the development and optimization of a novel qualitative method for the determination of the various types of hydroxyl groups present in biodiesel production streams. In the first study, the use of 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane as a phosphitylation reagent for quantitative ³¹P-NMR analysis of the hydroxyl groups in biodiesel process samples has been developed. Subsequently a characteristic chemical shifts library is developed with model compounds to provide quantitative data on the concentration of biodiesel precursors, intermediates and final product. The last part of this thesis depicts the results of an industrial trial based on the novel biodiesel analytical method developed earlier.

Waste to energy (WTE) has been used in some Asian and European countries for decades. It has been re-considered in Hong Kong to solve the landfill space shortage problem since 2000. The consideration was planned for over 10 years but still has not been implemented due to political and social problem. Due to all landfills will be reaching their designated capacity before 2020, there is urgent need to explore other means of disposal. Based on international experience in this study, three technologies are identified to have high potentials, moving grate incineration, anaerobic digestion and plasma gasification. Although moving grate incineration are the most widely used as core technology for large scale plant, anaerobic digestion and plasma gasification are more socially acceptable due to its technological difference. Plasma gasification is a newer technology on waste treatment that the government should explore on the integrated waste management facilities project. The use of all technology variants will cause certain social impacts, and the best use of the facilities affects the benefit to society and influences the public’s view. In the study, the IWMF and OWTF are generally support by the public, but the public’s views are dispersed. Currently the public concerns about the site selection and health & safety problem of both government plan, and required the improvement of recycling and source separation system. Also public are lacking the knowledge of waste management option that Hong Kong could take to solve the waste problem, indicating the need of better government-general public communication mechanism. The government has to do better planning for the use of WTE and engage the public on different level to minimise the social opposition voice in order to proceed with the WTE plan. Policy to gain public support and remove obstacle from private sector are the major works required instead of pure technical report on the choice of WTE facilities as the government has done in the last decade. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Low cost cellulosic wastes like paper sludge, municipal wastes, solid wastes from food, packing etc. contain a high amount of cellulose which can be converted to bioethanol by two steps: (1) solubilization of cellulosic fibers to monosaccharides (2) conversion of monosachharides to bioethanol via fermentation. At present the implementation of this technology has been deterred by high cost for enzymes. Enzymatic hydrolysis of cellulosic fibers shows a biphasic behavior with an initial fast step followed by a slow step leading to low cellulose conversion rates. Low hydrolytic conversion rates necessitate the use of a high enzyme dosage to obtain meaningful cellulose conversion rates which make the implementation of this entire technology economically infeasible. The objective of this study is to get a better understanding of the mechanism of enzymatic hydrolysis of fibers to glucose and to investigate the effect of cationic polymers on enzymatic hydrolysis rates. To achieve the first objective, we performed experiments so as to study changes in morphological and physiochemical properties like fiber length, percentage of fines, crystallinity index, kink angle, kink index, mean curl, total organic carbon and glucose production with time. We used bleached kraft softwood, hardwood, and unbleached softwood fiber as cellulosic substrate and pergalase as cellulase enzyme. All of the experiments were carried out at experimental conditions of a temperature of 50 .C and a pH of 5.0 which maximize enzymatic activity. We studied the impact of recycling and refining on hydrolysis rates by measuring total organic carbon and glucose production. We found that refining increases enzymatic conversion rates by about as much as 20 %, however refining being energy intensive makes its implementation economically unfavorable. We found a novel way of enhancing hydrolysis rates by the use of cationic polyacrylamides. The effect of cationic polacrylamides was studied on both hardwood and softwood fibers at similar experimental conditions. Cationic polyacrylamides produced a maximum rate increase of 20 % in hydrolytic conversion rates for hardwood fibers. Even though, the increase in hydrolysis rates for softwood fibers was smaller than hardwood fibers, it was still significant. We further studied the effect of parameters like polymer concentration, cationicity and molecular weight to find a relation between properties of polymers and the increase in enzymatic hydrolysis.

Thesis (M.S.)--University of Tennessee, Knoxville, 2002. / Title from title page screen (viewed Feb. 27, 2003). Thesis advisor: Atul Sheth. Document formatted into pages (ix, 70 p. : ill. (some col.)). Vita. Includes bibliographical references (p. 67-69).

Thesis (PH.D.)--Michigan State University. Chemical Engineering, 2008. / Title from PDF t.p. (viewed on Aug. 11, 2009) Includes bibliographical references (p. 179-189). Also issued in print.

The work presented in this thesis was carried out with a particular view of enhancing the of coal fired fluidised bed hot gas generator (HGG) at the Cantley factory of British Sugar. It covers combustion of coal and biomass and their blends also called co-firing in a fluidised bed combustor. Particularly it focuses on the effect of introduction of moisture as part of fuel or injection of water into the bed on the reduction of excess air to get a stable bed temperature. Although this thesis is focused on increasing the throughput of the HGG, the study has a broad application and can be beneficial in utilising relatively cheap, poor quality, unprepared biomass materials. The results of this study can be helpful in devising systems to deal with wastes from different industries in co-combustion with a fuel of higher calorific value such as coal. Thus the study will have dual impact on the industry; addressing waste management issues on one hand and producing useful energy on the other. This may contribute towards meeting the targets of Kyoto Protocol by reducing emissions of carbon dioxide (COi) as biomass is thought to be COa neutral. The fluidised bed at Cantley is used to dry animal feed and has a design capacity of 40 MW but due to limitations of flow of fluidising gases caused by high flow resistance through sparge pipes, the combustor is running under capacity. Consequently, some of the animal feed has to be dried by using expensive oil fired drier. In any combustion system excess air is used to control combustion temperature. In fluidised bed combustion excess air is used to control bed temperature. If the bed is cooled by other means the requirement of excess air can be reduced. This is the basic idea behind this study which is aimed at enhancing the capacity of the HGG by cooling the bed and thus reducing excess air requirements. The excess air thus spared can be used to combust more coal in the bed and thus will reduce dependence on oil fired dryer and will have financial benefits for British Sugar. Different fuels including wood pellets, wood chips and sugar industry by-products such as vinasse, raffinate and pressed pulp were fired/cofired with Thoresby coal in a fluidised bed test rig installed at the University of Glamorgan. The blends of wood chips and pressed pulp with coal are co-fired at different moisture contents. The tests were conducted at different thermal inputs at a wide range of excess air levels. Most of the work is focusedon the combustion of blends of coal and pressed pulp in different proportions. It was found that the maximum proportion of the pressed pulp in the blend with coal which could be burned successfully in the fluidised bed is 50%. During combustion of different coal-pulp and coal-wood chips blends it was found that excess air requirement is reduced by around 20% in comparison to coal only firing, over the range of the operating conditions tested. Because of the presence of potassium in pressed pulp, which could cause agglomeration during combustion in fluidised beds, longer term tests were carried out with 50/50 blend of coal and pulp. No signs of agglomeration were observed when the rig was fired for 8 days for almost 7 hours a day. However, Scanning Electron Microscopy (SEM) analyses of bed samples taken at the end of every day have shown the accumulation of potassium in the bed up to 1%. For comparison purposes tests were also carried out by co-firing coal with raffiante and vinasse and then it was observed that the bed defluidised relatively quickly, within 40 minutes of co-firing. Post experiment SEM analysis confirmed the accumulation of potassium in the bed which was found to be around 8% for raffinate and around 10% for the vinasse experiment. It was found that the pulp is difficult to deal with and particularly its feeding into the fluidised bed could be a potential problem. Therefore, injection of water into the bed, a relatively cheaper and adaptable option, was also investigated. It was found that emissions of carbon monoxide due to incomplete combustion or water gas shift reaction would not be a problem as long as the bed temperature is controlled above 800 °C. It was found that the injection of water at a rate of 4.5 1/h into the bed fired at 17 kW reduced the air flow requirement by around 7.5 m3/h which corresponds to a reduction of almost 20% which agrees with the finding with coal-pulp blends co-firing. This excess air can be used to burn around 5 kW equivalent of more coal and thus result in an increase in the thermal capacity by around 30%. Therefore, it may be possible to enhance the thermal capacity of the HGG at Cantley by 30% by injecting water into the bed or by co-firing coal and pulp.

A key engineering challenge is a transition to cleaner sustainable energy supply that is derived from renewable resources. Furthermore, affordable access to this modern sustainable energy services for communities in particular poor rural and urban communities is crucial. Microbial fuel cell (MFCs) is an emerging renewable alternative technology with potential to be self-sustaining that could alleviate the energy crisis and reduce environmental pollution. The use of the MFC as a dual system for electricity generation and wastewater treatment is been well reported in literature. Manganese dioxide (MnO2) is an effective electro-catalyst that have been used for alkaline fuel cells and battery application. MnO2 have a high conductivity and high structural porosity for ion and gas transport. In addition, MnO2 have a favourable crystal morphology, which makes it particularly useful for improving oxygen reduction reaction in the fuel cell. Graphene (GO) will be loaded on MnO2 surface as an effective support material. GO is a material good for electrical conductivity and their mechanical strength is applicable in electro-catalytic activities and is cost effective. In this work, a constructed dual chamber MFC configuration with graphite rod electrodes, MnO2-GO electrocatalyst and proton exchange membrane (PEM) using municipal sewage wastewater to generate electricity. The MnO2 as an alternative electro catalyst used for oxygen reduction reaction (ORR) in the MFC while using reduced graphene (rGO) as a support to enhance electrode surface area. Also addressing the effect of graphene material loading on MnOx catalyst for electrochemistry. The characterization of the MnO2-GO electrocatalyst have been analysed using X-Ray diffraction (XRD), Brunau-Emmett-Teller (BET) surface area and Fourier transform infrared spectroscopy (FTIR) for structural properties. Electrochemical techniques such as cyclic voltammetry (CV) for MnO2-GO electrocatalyst. Thermal gravimetric analysis (TGA) for the thermal properties, and the morphological properties probed by Scanning Electron Microscopy (SEM). The dual chamber MFC design functioned successfully and tested for energy generation from municipality sewage wastewater. The maximum voltage of 586 mV reached during MFC operation with various sewage municipal wastewater COD of 100-300mg/L. The maximum power density of 248 mW/m2 with resistance of 16.98 Ω and highest current density of 1.72mA/m2 was observed at the first cycle as compare to other cycle. The lowest value of 0.002159 mA/m2 obtained at the end of 10 days. The content of municipality sewage wastewater is capable of generating electricity. The physico-chemical properties of α-MnO2 exhibits excellent cycling stability on the electrochemical. This excellent cycling stability of α-MnO2 as a super capacitor electrode material. In addition, the graphene material loading on α-MnO2 has improved the electro catalytic activity, which influences the kinetics of the reduction reaction. The α-MnO2 synthesized BET analysis specific surface area of 134.61m2 g-1 reported. MFC technology has the potential to finds its own niche in the energy industry as it is becoming more and more sustainable due to the lower cost of electro catalyst materials. Power densities of 248 mW/m2 using wastewater with COD of 291mg/l were much higher than those previously obtained using low strength wastewater. These results have opened doors for further investigation of improving electro catalysis, utilized high concentration wastewater with high COD and improved MFC design including electrode materials. / Civil and Chemical Engineering / M. Tech. (Chemical Engineering)