Anaerobic digestion technology has not gained widespread acceptance on UK farms due mainly to the long return on investment periods involved. It has been suggested that co-digestion of agricultural and industrial wastes may enhance the economic viability of such installations. Batch and continuous digestion of cattle slurry and organic industrial wastes was carried out in specially constructed pilot plant digesters, to determine optimum mixtures of waste and digester loading rates. A total of 10 different wastes were tested, on a batch digestion basis, for their potential to co-digest with cattle slurry. Of these, 3 were chosen for continuous pilot plant trials, due to either a need to provide a disposal route for the waste, or positive effects of the waste on methane productivity. Chicken manure was found to slightly enhance methane productivity, but ammonia inhibition of methanogenic bacteria was noted over time. The organic fraction of municipal household waste (OFMSW) significantly enhanced digester methane productivity, while fish offal (FO) slightly enhanced methane productivity when added to the digester in small quantities, but quickly caused digester failure when added in larger amounts. An economic model of a digestion facility was developed and used to show the financial benefits of co-digestion.

Electrical power generation from wind energy has been recognised as one of major realistic energy sources in CO2 emission reduction worldwide. However, matching power generation with the load demand remains a great challenge, due to the nature of wind energy intermittency. The thesis addresses this issue by developing a new system with the structure of a hybrid connection of the wind turbine and compressed air energy storage. A scroll air motor is adopted to serve as an “air-electricity transformer” to compensate the power output during the period of low wind speed. The complete mathematical model and a suitable management and control strategy for the whole hybrid system are developed in the thesis. The simulation study has demonstrated that the proposed new hybrid wind turbine system is feasible and has potential for industrial applications. The prototype of hybrid wind turbine is successfully constructed in the author’s group. And the experimental results finally prove the concept of the new hybrid wind turbine. At last, the experimental system result analysis is described in this thesis. Simulation and experimental study shows that the proposed hybrid wind turbine system is technically feasible with energy efficiency around 50%.

O presente trabalho tem por objetivo disponibilizar metodologia para o projeto de tratamento de esgoto sanitário através de disposição oceânica com utilização de emissário submarino, para localidades de pequeno porte. Também apresenta metodologia simplificada para obtenção de alguns dados oceanográficos necessários, na perspectiva de atender aos administradores dessas pequenas prefeituras envolvidas nas questões de atendimento de sua população quanto aos serviços de tratamento dos esgotos sanitários. Esses municípios, por serem pequenos e em país em desenvolvimento, carecem de recursos financeiros para as soluções convencionais de tratamento de esgotos sanitários. O trabalho contém uma revisão da bibliografia técnica relativa ao processo objeto deste estudo, não só referente ao projeto hidráulico como também à estabilidade física da tubulação do emissário assentada no leito do mar. Julgou-se necessário a realização, deste trabalho depois que se verificou que a implantação de emissários submarinos com diâmetros até da ordem de 300 mm, em geral tem seus custos inferiores aos dos sistemas convencionais. / This paper aims to provide a simplified methodology for the treatment design of sewage disposal through the use of oceanic outfall locations for small towns. It also features simplified methodology for obtaining oceanographic data needed for those small municipalities management. As these cities are usually on a development phase and have restricted resources to invest on its needs, the designed system becomes very attractive due to its low capital requirement. This work includes a technical review on the subject of this case study, not only regarding the water issues but also related to its physical stability of the outfall pipe at the bottom of the sea.It was felt necessary to organize this work after it was found that the introduction of submarine outfalls with diameters up to around 300 mm, has its costs below those of conventional systems. The most important result from this work is the competitiveness conclusion of the required implementation investment of submarine outfalls, with diameters up to 300 mm.

The following research thesis focuses on methods of controlling nitrogen oxides (NO_x) and particulate matter (PM) emissions emitted from a low temperature diesel exhaust. This involves studying the influence of hydrogen (H₂) on various aftertreatment devices such as hydrocarbon selective catalytic reduction (HC-SCR) over silver-alumina (Ag-Al₂O₃) catalysts for lean NO_x reduction, platinum diesel oxidation catalysts (DOC) for nitrogen dioxide (NO₂) production and passive regeneration methods for the diesel particulate filter (DPF). H₂ was implemented on-board either through diesel exhaust gas fuel reforming or via the simulation of ammonia (NH₃) dissociation. Both methods showed to be very effective in enhancing the activity of a silver HC-SCR catalyst for the reduction of NO_x with conversions reaching 90% with the aid of an upstream DPF. A combined DOC and catalysed DPF (cDPF) configuration proved promising for passive regeneration in the presence of reformed exhaust gas recirculation (REGR). The addition of H₂ over the DOC led to an improved catalyst light-off temperature and increased rate of oxidation for NO₂ production. Implementing filtered EGR (FEGR) removes the hydrocarbon (HC) and soot recirculation penalty, thus minimising particulate growth which results in a significantly reduced engine-out soot emission during exhaust gas recirculation (EGR) and hence, an improved NO_x/soot ratio. Introducing fuel components which enhance the cetane number and oxygenate the diesel fuel allow better control of the NO_x/soot trade-off with improved soot oxidation properties.

The objective of this study is to develop a membrane-based generic treatment scheme for wastewaters of indigo dyeing process of denim industry, based on water reuse. For this purpose, firstly the performances of microfiltration (MF), coagulation, and ultrafiltration (UF) processes were evaluated as pretreatment alternatives and the best pretreatment alternatives appeared to be single stage 5 &micro / m MF and sequential 5 &micro / m MF followed by 100 kDa UF providing high permeation rate and high color retention. These two pretreatment alternatives were compared based on the performance of nanofiltration (NF) using NF 270 membrane, and the best pretreatment process was evaluated as 5 &micro / m MF that provided 87-92% color and 10% chemical oxygen demand (COD) retention. After the pretreatment tests, three different NF (NF 270, NF 90, Dow Filmtec, USA and NF 99, Alfa Laval, Denmark) and two different reverse osmosis (RO) membranes (HR 98 PP and CA 995 PE, Alfa Laval, Denmark) were tested to produce reusable water. Permeate COD and color performances of the tested NF and RO membranes were similar and satisfactory in meeting the relevant reuse criteria, while permeate conductivity was satisfactory only for HR 98 PP RO membrane and for NF 90 membrane. On the other hand, NF 270 membrane was superior to the other membranes in terms of permeation rate. For NF 270 membrane / cumulative color, COD and conductivity retentions were found to be 93 %, 92 %, and 60 %, respectively. When the developed process chain (5&micro / m MF+ NF 270) was also tested for a dilute indigo dyeing wastewater, it was found out that the developed scheme works similarly and is generic for indigo dyeing wastewaters.

Bioflocculation happens naturally and microorganisms aggregate into flocs during wastewater treatment. It is critical to understand the mechanisms of bioflocculation and its impact on the following solid/liquid separation process since seperation by settling is one of the key aspects that determine the efficiency and the overall economy of activated sludge systems. Bioflocculation occurs via extracellular polymeric substances (EPS) and cations by creating a matrix to hold various floc components together so the cations become an important part of the floc structure. The main objective of this study is to investigate the effects of monovalent cations specifically potassium and sodium (K and Na) on the bioflocculation, settleability and dewaterability of activated sludge. The particular aim is to grow the mixed culture microorganisms in the presence of specific cation so that the effect of cation on the stimulation of EPS production can be seen. In order to achieve this aim, semi-continuous reactors were separately operated at concentrations of 5, 10, and 20 meq/L of each cation with mixed culture bacteria and fed with synthetic feed medium representing influent to the activated sludge systems. Also, a control reactor at low cation dose was operated for each reactor set. The effective volume of the reactors was 2 L with 8 days of sludge residence time (SRT) and pH was kept at 7.7&plusmn / 0.3. The activated sludge reactors were operated until the reactors reached steady state and then related analyses were conducted. It was found that addition of potassium and sodium ions at increasing concentrations resulted in increase in total polymer concentration. However, potassium ions promoted the synthesis of both polysaccharide and protein type polymers whereas sodium ions tended to stimulate production of protein type polymers and had an affinity to bind more protein within the floc structure. Sodium sludges had lower hydrophobicity and higher surface charges, so sodium ions led to deterioration in flocculation of sludges. Addition of both these ions decreased the dewaterability, sodium ions had more detrimental effect on dewaterability of sludges compared to potassium ions. The examination of data related to settleability showed that potassium ions led to no drastic deterioration in settling characteristics of the activated sludge but the addition of sodium ions deteriorated the settleability. In addition, it was seen that while the addition of potassium ions to the feed led to a decrease in viscosity, increase in sodium concentration correlated with an increase in viscosity. Finally, the comparison of chemical oxygen demand (COD) removal efficiency of these cations showed that sodium is more efficient in COD removal.

The activated sludge process efficiency depends on separation of microbial cells from treated wastewater. Separation can fail due to a number of problems. One of these problems is sludge bulking which is non-settling situation of biomass. Former studies showed that phosphorus deficiency caused filamentous sludge bulking with increasing magnesium ion concentrations. The main objectives of this study are to find out the effect of magnesium ions on sludge properties in phosphorus deficient medium and to determine if there is any bulking. Three different concentrations of magnesium (0.5, 5, 15 meq/L) were added to three bioreactors which contained phosphorus deficient medium. In first set C: N: P ratio was 100:5:0.05. In second set, C:N:P ratio was elevated to 100:5:1. At steady state, physical characteristics including sludge volume index (SVI), viscosity, turbidity and dewaterability were determined. Besides concentration of extracellular polymeric substances (EPS) as well as conductivity was measured. By using API kits, bacterial identification was achieved. In first set phosphorus deficiency and increasing magnesium ion concentration caused filamentous bulking. Carbohydrate content of extracellular polymeric substance significantly increased by magnesium addition. Dewaterability of the system got worse and viscosity decreased. Sludge Volume Index (SVI) indicated severe bulking at all magnesium concentrations. By using biochemical tests microorganisms dominant in the system were determined In second set, all of the parameters indicated healthy flocculation. By magnesium addition, EPSp and EPSc increased. Dewaterability and settleability, improved by the presence of phosphorus with close values measured at different magnesiuim concentrations. Nocardia related genera of Corynebacterium and Enteric microorganisms were identified.

Waste production and management problems have increased in this century. Population growth and consumption patterns in developing societies are associated with this growth. During the last decades, some world organisations have contributed to a global discussion and common resolutions. Concerns about the environment and sustainable development have been soundly highlighted. The European Union through its five Environment and Development Programmes as well the Directives and other special Regulations have responded that Agenda 21. The complexity and historical context of integrated and sustainable waste management is studied within the context of the construction industry in Portugal. International experience and knowledge were also drawn upon to add to the local knowledge. The study classifies the debris trail. The deconstruction process is studied in order to illuminate the relationship with the nature of the debris trail. This is the core of the research which seeks to make a contribution to the understanding of this relationship and forms the basis for the development of a dynamic construction and demolition estimating and assessment model. The work is based on case studies derived by observation from five complex and holistic case studies in Lisbon, cases studies reported from other countries and from work by others undertaken in France. Soft Systems Methodologies are used to illuminate the qualitative concerns. The quantitative information from practice is placed along side the qualitative data to give further insight into the issues being studied. The difficulties of insufficient actor involvement and participation in the process are also discussed. Systems Dynamics methodologies are used to define a dynamic model using data from the sources referred. The model is intended to assist the assessment and estimation of the characteristics of the debris trail. The output of the dynamic model will contribute to a national strategy and plan for the construction and demolition waste stream in Portugal within the context of European Union strategies and guidelines.

Thesis (M.Arch.) - Carleton University, 2007. / Includes bibliographical references (p. 124). Also available in electronic format on the Internet.

The Fabriconda wave energy converter is a submerged tube lying perpendicular to incoming wave fronts. The tubeconsists of a series of smaller fabric tubes, called cells, joined together longitudinally to form a larger central tube. The cells and central tube are flooded with water. Cross-sectional area changes with pressure due to the cells changing shape. The Fabriconda is therefore distensible, enabling it to extract energy from external waves. Waves induce a series of travelling bulges, and an internal oscillatory flow, in both the central tube and cells. If the speed of these bulges is close to the phase speed of the external wave, energy is progressively transferred to this flow. A power take-off system terminates the tube at the stern. A 1D mathematical model has been developed to predict the power captured by the Fabriconda, based on the application of the conservation of momentum and mass to the flow in both the central tube and cells. An analytical solution of this model has been found using an assumption of harmonic behaviour. A time-stepping finite difference solution was also derived and found to agree with the analytical solution. The results from these models have been compared with measurements. The cross sectional shape of the Fabriconda depends on the ratio between cell and central tube pressure, while the free bulge speed is dependent on the sum of the central tube and cell distensibilities. Both �ndings were supported by measurements. Measurements found that power generally peaked closer to the resonance frequency than predicted and was dependent on initial pressure. The effect of tube length on the frequency dependency of power capture and the presence of secondary peaks led to the conclusion that normal mode effects are significant to the Fabriconda's performance. This work has determined the operating principles of the Fabriconda and demonstrated that it can extract energy from waves. Predictions of full scale performance and commercial viability are not considered.