Microbial fuel cells (MFCs) are potentially advantageous as an energy-efficient approach to wastewater treatment. For single-chamber tubular MFCs, anode effluent is used as catholyte instead of tap water or buffer solutions. Therefore, exposing cathode electrode to atmosphere could be also considered as a passive aeration for further aerobic oxidation of organics and nitrification. Based on several bench-scale studies, a 200-L scale MFC system with passive aeration process has been developed for treating actual municipal wastewater after primary clarification. The integrated system was able to remove over 80% organic contaminants and solid content from primary effluent. Through parallel and serial electricity connection, the power output of ~200 mW and the conversion efficiency of ~80% for charging capacitors were achieved by using commercially available energy harvesting device (BQ 25504). The treatment system is energy-efficient for the energy saving from aeration and sludge treatment while partial energy recovery as direct electricity can be utilized on site to power small electric devices. However, the post treatments are required to polish the effluent for nutrients removal. / Ph. D.

Microbial fuel cells (MFCs) are potentially advantageous as an energy-efficient approach for wastewater treatment. Integrating membrane filtration with MFCs could be a viable option for advanced wastewater treatment with a low energy input. Such an integration is termed as membrane bioelectrochemical reactors (MBERs). Comparing to the conventional membrane bioreactors or anaerobic membrane bioreactors, MBER could be a competitive technology, due to the its advantages on energy consumption and nutrients removal. By installing the membrane in the cathodic compartment or applying granular activated carbon as fluidized bed materials, membrane fouling issue could be alleviated significantly. In order to drive MBER technology to become a more versatile platform, applying anion exchange membrane (AEM) could be an option for nutrients removal in MBERs. Wastewater can be reclaimed and reused for subsequent fermentation use after a series MFC-MBR treatment process. Such a synergistic configuration not only provide a solution for sustainable wastewater treatment, but also save water and chemical usage from other non-renewable resource. Integrating membrane process with microbial fuel cells through an external configuration provides another solution on sustainable wastewater treatment through a minimal maintenance requirement. / Ph. D.

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Effective wastewater treatment is needed to reduce the water pollution problem. However, massive energy is consumed in wastewater treatment, required to design an innovative system to reduce the energy consumption to solve the energy crisis. Integrated photobioelectrochemical system (IPB) is a powerful system to combine microbial fuel cells (MFCs) and algal bioreactor together. This system has good performance on the organic degradation, removal of nitrogen and phosphorus, and recover the bioenergy via electricity generation and algal harvesting. This dissertation is divided to twelve chapters, about various aspects of the working mechanisms and actual application of IPB. Chapter 1 generally introduces the working mechanisms of MFCs, algal bioreactor, and modeling. Chapter 2 demonstrates the improvement of cathode material to improve the structure and catalytic performance to improve the MFC performance. Chapter 3 describes the process to use microbial electrolysis cell (MEC) to generate biohythane for the energy recovery. Chapters 4 and 5 demonstrate the application of stable isotope probing to study Shewanella oneidensis MR-1 in the MFCs. Chapters 6 to 8 describe the application of models to optimize MFC and IPB system performance. Chapter 9 describes the strategy improvement for the algal harvesting in IPB. Chapter 10 describes the application of scale-up bioelectrochemical systems on the long-term wastewater treatment. Chapter 11 finally concludes the perspectives of IPBs in the wastewater treatment and energy recovery. This dissertation comprehensively introduces IPB systems in the energy recovery and sustainable wastewater treatment in the future. / Ph. D. / The resource of pure water becomes more and more valuable, and the large discharge of the wastewater into the environment would even cause the environmental pollution. Thus, the wastewater is a necessary method to remove the organics out of the wastewater. However, the large energy consumption is a critical issue to solve due to the global energy burden. How to reduce the energy consumption in the wastewater treatment is the required step to achieve the sustainable water treatment. Integrated photobioelectrochemical system (IPB) is a new promising technology, alternative to the traditional wastewater treatment techniques (e.g., anaerobic digester or activated sludge reactor) with low energy consumption. The IPB system was to combine microbial fuel cells (MFCs), which is a typical bioelectrochemical system (BES), and the algal bioreactor together, to achieve the performance on the organic degradation, removal of nitrogen and phosphorus in the wastewater, and recover the bioenergy via electricity generation and algal harvesting. The system was proved to be effective, but most of the IPB systems were only proved to work in the laboratories, and there is still a large potential space to improve the IPB system performance in the actual environment. Herein, this dissertation combines multiple studies about the IPB improvement and scaled-up process in the real wastewater treatment. Chapter 1 generally introduces what are MFCs, algal bioreactor and modeling simulations. Chapter 2 demonstrates the method about how to improve the MFC material to enhance the treatment performance for better MFC performance. Chapter 3 describes how to use BES to convert the organics to the renewable gas (e.g., H₂ and CH₄) to recover the energy. Chapters 4 and 5 demonstrate the application of stable isotope probing to study the microbial behavior in the MFC. Chapters 6 to 8 describe the applications of model simulations to optimize MFC and IPB performance. Chapter 9 describes the new reactor to improve the algal harvesting process to obtain more energy from the IPB system. Chapter 10 describes how to use the scale-up IPB system to treat the real wastewater treatment. Chapter 11 finally puts forward some perspectives of IPBs in the wastewater treatment and energy recovery. This dissertation comprehensively gives a big picture about the development of IPB systems in the energy recovery and sustainable wastewater treatment in the future.

Yes / Energy saving is an important consideration in process design for low cost sustainable production with reduced environmental impacts (carbon footprint). In our earlier laboratory scale pilot plant study of catalytic wet air oxidation (CWAO) of phenol (a typical compound found in wastewater), the energy recovery was not an issue due to small amount of energy usage. However, this cannot be ignored for a large scale reactor operating around 140–160 °C due to high total energy requirement. In this work, energy savings in a large scale CWAO process is explored. The hot and cold streams of the process are paired up using 3 heat exchangers recovering significant amount of energy from the hot streams to be re-used in the process leading to over 40% less external energy consumption. In addition, overall cost (capital and operating) savings of the proposed process is more than 20% compared to that without energy recovery option.

The implementation of an energy recovery system for retreiving otherways wasted energy is an effective method for reducing the overall energy consumption of a mobile machine. In a fork lift, there are two subsystems that can be effectively modified for recovering energy. These are the driveline and the lift/lower function of the mast. This study focuses on the latter by studying a recovery system whose main component is a hydraulic transformer consisting of a hydraulic motor, a variable displacement pump and an induction motor. Since the flow rate/pressure - ratio can be modified, the utilization of the hydraulic transformer enables downsizing of the accumulator volume. However, the decrease of the gas volume leads to an increase in the compression ratio of the accumulator, which in terms leads to higher gas temperatures after charging and consequently to higher thermal losses during holding phase. In order to reduce these losses, a thermally regenerative unit was implemented to the gas volume of an accumulator to reduce the temperature build up during charging. In this study, the effect of improving the thermal characteristics of the accumulator to the efficiency of the whole energy recovery system is investigated by means of measurements.

Particleboard was invented to increase the utilization of wood and it soon became an important core material for furniture production. Nowadays, other industries such as the pulp and papermaking industry and the thermal energy recovery industry claim the same type of raw material. This leads to increasing competition and higher prices than in the past when that kind of wood raw material was widely available and of low price. The particleboard-producing industry is therefore seeking opportunities to reduce the competition and ensure the future supply of lignocellulosic raw material for their products. The purpose of the work summarised in this thesis was to investigate the strategic supply of lignocellulosic raw materials for particleboard production and to evaluate alternatives for the supply of lignocellulosic raw material for particleboard production. To encompass the complex field of strategic raw material supply, several publications have considered different stages along the supply chain. These papers range from empirical studies to practical tests on a laboratory scale. In this thesis, some of the papers are linked together, building the base for the overall results. The results show that the task of increasing the supply of lignocellulosic raw material as primary raw material source is limited by several factors, but that improved product design coupled with a suitable recycling concept can greatly increase the availability of lignocellulosic raw material as a secondary source. Alternatively, the use of non-wood plants might be an opportunity to substitute wood as raw material but there are still some problems relating to the particle properties which must be overcome first.

Since the realisation of the computer, and shortly after the inception of artificial intelligence (AI), there has been an explosion of research solving human-level tasks using autonomous entities that are able to learn about an environment by observing and influencing it, known as intelligent agents (IA). This potent AI technique has yet to filter into the field of thermoscience, where the conceptual design and optimisation of complex energy systems has been a particularly challenging problem. Much of the design process still requires human expertise. But with the continual increase in computational power and the use of IAs, it is now time to shift the responsibility from the human to the computer. This research attempts to answer the question of whether it is possible for a computer to conceptually design a complex energy system autonomously, from inception. The complex energy system to be designed and optimised is a thermoacoustic heat engine (TAHE), which converts thermal to acoustic power. The complexity of its physical behaviour and its many design parameters makes it a challenging energy system for conceptual design and optimisation and consequently an ideal candidate for this particular research. The TAHE is designed for low temperature waste heat utilisation from a baking process. In this work an approach is employed that is based on a reinforcement learning intelligent agent (RLIA). The RLIA is first employed to simultaneously optimise thirteen design parameter values. The RLIA was able to learn key design features of a TAHE which lead to the reduction in acoustic losses and an acoustic power from the engine of 495.32 W, when the thermal power input was 19 kW. For the main experiment, the RLIA must conceptually design the TAHE from scratch, changing both the parameter values and the configuration of the device. The results have shown the remarkable ability of the RLIA to identify several key design features of the TAHE: the correct configuration of the device, selecting designs that reduce acoustic losses, create positive acoustic power in the stack region and determine the region of optimality of the design parameter values. The RLIA has shown a great capacity to learn, even when contending with a complex environment and a vast search space. With this work we have introduced RLIAs as a new way approach to such multidimensional problems in the field of thermoscience/thermal engineering.

Photovoltaic (PV) system is one of the most prominent energy sources, producing electricity directly from sunlight. In additionally, it is easy to install and is supported financially by many governments as part of their strategy to reduce CO2 gas emissions, and to achieve their agreed set of reduction targets by 2020. In the meantime, researchers have been working on the PV system to make it more efficient, easy to maintain, reliable to use and cost effective. In the stand-alone PV system, a battery is required. This is due to the fluctuating nature of the output energy delivered by the PV arrays owing to the weather conditions and the unpredictable behaviour of uses with regard to the consumption of energy. During the hours of sunshine, the PV system is directly feeding the load and any surplus electrical energy is stored in the battery at a constant current. During the night, or during a period of low solar irradiation, the energy is supplied to the load from the battery. However, the stand-alone PV system is designed to provide an acceptable balance between reliability and cost, which is a major challenge to the designer owing to the approaches used to size the PV arrays and the battery bank. As a result, the unpredictable, quick daily changes on the PV output is not dependable. Moreover, battery performance, length of life and energy efficiency depends on the rate at which it is discharged. Therefore, it is essential to use other methods to deal with any quick variation in energy. In this thesis, a super capacitor is used to solve this problem, as it can deal with the fast-changing weather, or a rapid variation in the energy requirements of the customer. A critical evaluation with in-depth analysis of the placement and the implementation for the super-capacitor in the PV standalone system has been carried out. The results show, super-capacitor capacitance and the converter efficiency affect the delivered load energy. However, the bi-directional topology performs better than uni-directional under the same conditions. Finally, a further improvement of the system at component level, has been developed through an energy recovery snubber for the switching transition and achieved a recovery of energy for the resistive load, 94.44% for the turn on transition and 92.86% for the turn off transition. Moreover, for the inductive load, 78.33% and 97.33% of energy has been recovered for the turn on and for the turn off transition respectively.

<p>This thesis deals with the study and comparison of on-chip LC Oscillators, used in energy recovery clocking, in terms of Power, Area of Inductor and change in load capacitance. Simulations show how the frequency of the two oscillators varies when the load capacitance is changed from 5pF to 105pF for a given network resistance. A conventional driver is used as a reference for comparisons of power consumptions of the two oscillators. It has been shown that the efficiency of the two oscillators can exceed that of a conventional driver provided the distribution network resistance is low and the on-chip inductor has a high enough Q value. Conclusions drawn from the simulations, using network resistances varying from 0Ω to 4Ω, show that the selection of the oscillator would depend on the network resistance and the amount of area available for the inductors.</p>