A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg 10th of October 2016 / Thermal pyrolysis is one of the viable technologies suitable for the management of organic solid waste, which has become a global challenge over the years. This is due to the non-biodegradability of these materials and their continuous usage across all segments of man’s daily activities. Effectiveness of the method is in converting these materials under controlled process conditions, that enable the optimization of the fraction of interest, such as the liquid fraction also referred to as pyrolytic oil with a near zero pollution effect on the environment. The main setback in the production of the liquid fraction include low yield, presence of sulphur and other aromatic compounds which have been linked to environmental pollution and health complications. This study focuses on improving the liquid fraction yield and composition obtainable from pyrolysis process. Latex natural rubber (obtained from Hevea Brasiliensis) was pyrolysed and its products compared with that of the used tyres. The production of pyrolytic oil from used tyres and natural rubber was performed using thermal and catalytic pyrolysis processes. The operating temperature range of 375 to 750 oC (at an interval of 75 oC) at a heating rate of 15oC/min and feed material particle sizes of 2, 4, 6, 8 and 10 mm were used. In addition, Zeolite NaY was synthesized from Lawani Benin River Kaolin (LBK) at a synthesis time and temperature of 9 h and 100 oC respectively, using hydrothermal synthesis method, and used for catalytic pyrolysis. The chemical characterisation revealed pyrolytic oil composition to be a complex mixture of aliphatic, aromatics, polycyclic aromatic hydrocarbons and other oxygen, nitrogen, sulphur and chlorinated compounds in small proportions. The non-catalysed and catalysed pyrolysis using natural rubber resulted in pyrolytic oil with 80 and 66% of aliphatic, 12 and 15% aromatic (with polycyclic aromatic hydrocarbons concentration of 2 and 1%). The non-catalysed and catalysed pyrolysis using used tyres yielded pyrolytic oil with 42 and 32% of aliphatic, 34 and 39% aromatic (with polycyclic aromatic hydrocarbons concentrations of 18 and 23%). The kinetics of the thermal degradation with the aid of a thermogravimetry and differential thermogravimetry analyzer was performed over a temperature range of 30 to 800 oC at a heating rate of 15, 20 and 30oC/min. Results showed that natural rubber displayed higher activation energy than used tyres, with respect to the heating rates. This is an indication that natural rubber is more difficult to thermally decompose than used tyres. The distillation temperature of the distillates was within the temperature range of the conventional petrol and diesel. The composition of the distillates revealed carbon chain length of C5-C30 with majority being C8 – C10. A spark ignition generator engine was used to perform the combustion tests for the various pyrolytic oil distillates and petrol blended in the ratio 0, 5, 10, 15 and 20% successfully without engine modification. For the fuel consumption with respect to generator run time, it was observed that an optimum of 20% natural rubber pyrolytic oil distillates (NRPD)-Petrol blend gave comparative fuel consumption behavior with that of commercial petrol. Furthermore, the 20% NRPD distillates gave optimum fuel consumption and power. Hence, a significant yield improvement and combustion performance were observed for the pyrolytic oil derived from natural rubber than that of used tyres. Further treatment of the pyrolytic oil distillates could pave the way for effective use of the oil as chemical feedstock for industries, or as substitutes for fossil fuel. It was also requisite to develop a mathematical model which adopts thermogravimetry analyser (TGA) as a dynamic apparatus to predict weight change of a material as it degrades with time at a fixed temperature. The proposed models were in three consecutive phases which were classified into three time zones 0 ≤ t ≤ t1, t1 ≤ t ≤ t2 and t ≤ t2. The general model equation for the first phase of degradation was 2 0 1 2 0 ( ) t T w t w e   , while the second phase model was and at the third phase, it is assumed that the limit of weight loss (in the second phase equation) as t tends to ∞ gives a value k , at which change in weight loss with time is negligible. The proposed model was used to plot graph of weight loss versus time at different fixed temperature which fitted well with the experimental TGA and had a characteristic pattern fitted closely to the second phase degradation of the fixed bed reactor. / MT2017

Orientador: Afonso Lopes / Banca: Leomar Paulo de Lima / Banca: Newton Scala Junior / Banca: Murilo Coelho Theodoro Neves / Banca: Priscila Sawasaki Iamaguti / Resumo: Preocupações com o esgotamento do petróleo, as demandas crescentes por energia e os regulamentos de emissões, tem motivado a comunidade científica a buscar alternativas estratégicas. Diante de tal contexto, a produção e a utilização do biodiesel em motores de ciclo diesel é um tema de muito interesse e representa uma janela de oportunidades para o Brasil, pois este é um combustível de cunho socioambiental, capaz de minimizar a emissão de poluentes advindos das emissões de escape. Entendendo que este é assunto que compreende as esferas econômicas, jurídicas e socioambientais, o presente trabalho teve por objetivo discorrer sobre os padrões para controle de emissões de escape em máquinas agrícolas, bem como comparar a opacidade da fumaça de um trator agrícola funcionando com óleo diesel B S50 e proporções (B0, B5, B15, B25, B50, B75 e B100) de biodiesel de palmeiras (babaçu, tucumã e buriti). A legislação brasileira está cada vez mais rigorosa em relação aos padrões de emissões advindas de gases de escape. Assim, na comparação com diesel BS50, notou-se que a opacidade da fumaça de um trator agrícola foi menor ao se aumentarem proporções de biodiesel, sendo que o biodiesel de babaçu (B100) foi o que apresentou melhor resultado para os fatores tipo e proporção de biodiesel. / Abstract: Concerns about the depletion of oil, growing demands for energy and emissions regulations, have motivated the scientific community to get strategic alternatives. In this context, the production and use of biodiesel in diesel engines is a topic of great interest and represents a window of opportunity for Brazil, since this is a socioenvironmental fuel, capable of minimizing the emission of pollutants from emissions. Understanding that this is a subject that encompasses the economic, juridical and socioenvironmental spheres, the present work had as objective to discuss the standards for control of exhaust emissions in farm tractor test, as well measure the opacity of the smoke of a tractor running on diesel oil B S50 and proportions (B0, B5, B15, B25, B50, B75 and B100) of palm biodiesel (babassu, tucumã and buriti). Brazilian legislation is becoming more stringent in relation to emission standards from exhaust gases. Thus, in the comparison with diesel BS50, it was observed that the opacity of the smoke of an agricultural tractor was smaller when increasing proportions of biodiesel, being that the babassu biodiesel (B100) was the one that presented the best result for the type factors and proportion of biodiesel. / Doutor

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 145-148. / by Theodore Robert Nunn. / M.S.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Concerns over environmental impacts and long term availability of liquid fossil fuels means that sourcing alternative, renewable transport fuels has increased in importance. To date, implemented approaches have concentrated on the production of liquid biofuels biodiesel and bioethanol from crops. Even though technology for implementation is readily available in the form of biogas production and upgrading, gaseous fuels have been largely overlooked in the UK. Research completed showed that if produced from indigenous crops using currently viable technology, it is energetically more favourable to produce gaseous fuels rather than biodiesel or bioethanol with gaseous fuels also delivering some emission benefits at end use. To date, the subsidy system supporting biofuel production has not functioned well. Research showed that if the subsidies approached the maximum allowable value, and when produced from waste materials, the production of gaseous fuels can be economic compared to liquid biofuels. Life cycle assessment has showed that utilising biomethane as a vehicle fuel could be an environmentally appropriate approach if the conventional use for biogas of combusting in a combined heat and power plant cannot utilise the majority of the excess heat produced. A two stage process to produce a hydrogen / methane blend was shown to be energetically favourable when utilising wheat feed, although hydrogen production was low. The process was not energetically favourable when food waste was utilised, indicating the importance of optimising process according to feedstock characteristics. Life cycle assessment of electrolytic hydrogen production using a range of energy sources found that electrolysis driven by renewable energy was a valid option for future deployment. However, given current feedstock availability, indigenous biofuel production, regardless of the fuel produced, could only make minor contributions to overall fuel requirements. As such, a range of fuel vectors, or a significantly greater commitment of land resources to fuel production, will be required in the future.

從微藻提煉的生物燃料，是化石燃料和其他生物燃料的優良替代品。藻類生物燃料屬碳中性，因為微藻為光自養生物，能經光合作用吸收二氧化碳，並將之轉化成碳氫化合物和脂肪。碳氫化合物和脂肪可用以提煉生物燃料。此外，微藻可以吸收廢水中的污染物作生長的營養，同時作污水處理。 / 本研究項目的目的為透過下述方法，降低藻類生物燃料的生產成本，並提高藻株的脂肪含量： (1) 篩選可以在污水自養培育，並有高產油量的微藻菌株，(2) 以兩階段培養方法，用處理過的污水作培養，從而提高油脂產，(3) 透過微藻毒理測試，和水質化學分析，研究處理後的污水中影響微藻生長的污染物和有毒物質。 / 這個研究中使用從沙田污水處理廠收集的二級處理污水，其水質亦被研究。幾種微藻菌株分別為小球藻 (Chlorella pyrenoidosa)，叢粒藻 (Botryococcus braunii) 和微綠球藻 (Nannochloropsis oculata)，從鰂魚池水分離出的小球藻 (Chlorella sp.1)，及兩種從處理污水中分離出的小球藻(Chlorella sp. 2, Chlorella sp. 3)。微藻菌株分別在培養基和處理污水中培養，並比較在兩種情況下的脂肪，脂肪酸，碳水化合物，蛋白質含量，生物質量和總有機碳。結果發現，雖然經處理的污水中營養成分非常低 (<0.11 mg / L活性磷，<9.68 mg / L硝酸根，<0.5 mg / L鉀離子)，所有研究的微藻菌株都能存活。在兩階段培養法下，首先以「氮含量充足階段」(培養基)提高生物質量，然後以「氮含量不足階段」(經處理污水) 培養，培養成本可以降低，同時提高脂肪生產率。在兩階段培養法下，叢粒藻的脂肪生產率比在人工培養基和經處理污水高2.6倍和7.13倍。 / 沙田污水處理廠處理的污水水質良好，並無驗出有害重金屬，雙酚A(BPA)，四溴雙酚A(TBBPA)和2,3,7,8-四氯二苯並二噁英(TCDD)。從藻類產生的生物燃料將不含有重金屬。 / 在這個研究中的叢粒藻 (Botryococcus braunii)，微綠球藻 (Nannochloropsis oculata)和小球藻 (Chlorella sp.1)都可以容忍雙酚A(BPA)，四溴雙酚A(TBBPA)，二氯苯氧氯酚 (TCS)和2,3,7,8-四氯二苯並二噁英(TCDD)。他們可以培育在其他來源的經處理污水。 / 利用經處理污水於兩階段培養法，是一種新的、更經濟的增加微藻油脂產量方法，亦可以配合任何其他方法，以減低藻類生物燃料的製造成本。 / Biofuel from microalgae can be an excellent substitute of fossil fuel and other biofuels. Algal biofuel is carbon neutral as microalgae are photoautotrophic. Through photosynthesis, microalgae can capture and convert carbon dioxide to hydrocarbons or lipids which can be used for biofuel production. Besides, microalgae can use pollutants from wastewater as nutrients for growth, which can serve as a wastewater treatment process. / The aims of the project are to lower the cost of algal biofuel production and boost up lipid content of algal strains by (1) screen a microalgal strain that can be cultivated in treated sewage autotrophically and give high oil yield, (2) use two phase cultivation, with treated sewage as medium, to boost up lipid productivity, (3) investigate heavy metals and some organic pollutants that may exist in treated sewage and can affect algal growth by performing algal toxicity test and chemical analysis of treated sewage. / The secondarily treated sewage used in this project was collected from the Sha Tin Sewage Treatment Works. The quality of the secondarily treated sewage was monitored. Chlorella pyrenoidosa, Botryococcus braunii and Nannochloropsis oculata from commercial source, and Chlorella sp. 1 isolated from tilapia fish pond water, and two species of algae, Chlorella sp. 2 and Chlorella sp. 3, isolated from treated sewage were investigated. Microalgal strains are compared by investigating the content of lipid, fatty acid, carbohydrate, protein, biomass and total organic carbon when cultivated in culture medium and treated sewage. Results found that although nutrients in treated sewage were very low (<0.11 mg/L reactive phosphorus, <9.68 mg/L nitrate and <0.5 mg/L potassium ion), all the microalgae investigated could grow reasonably well. Using two phase cultivation, with an initial nitrogen sufficient phase (artificial media) for biomass production, followed by nitrogen limitation phase (treated sewage), cost of cultivation could be reduced and the overall lipid productivity could be increased. Under the two phase cultivation, the lipid productivity of Botryococcus braunii was 2.6 and 7.13 fold higher than cultivated in artificial medium and treated sewage respectively. / Treated sewage from the Sha Tin Sewage Treatment Works was in good quality without harmful concentrations of heavy metal and BPA, TBBPA and TCDD. The microalgae could not absorb or adsorb significant amount of the harmful substances and the algal biofuel produced would not contain heavy metals. All the microalgae investigated in this project could tolerate BPA, TBBPA, TCS and TCDD. They could be cultivated in treated sewage from other sources. / Two phase cultivation using treated sewage is a new way for increasing lipid productivity from microalgae economically and can be combined with any other means for producing algal biofuel with lowest cost. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Kwan, Ka Ki. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 104-113). / Abstracts also in Chinese. / Acknowledgements --- p.i / Abstract --- p.iii / 摘要 --- p.Vi / Table of Contents --- p.viii / List of Figures --- p.Xii / List of Plates --- p.Xvi / List of Tables --- p.xviii / Abbreviations --- p.xx / Chapter 1. --- General introduction / Chapter 1.1 --- Fossil fuel, the major energy source nowadays --- p.1 / Chapter 1.2 --- Disadvantages of using fossil fuel --- p.3 / Chapter 1.3 --- Biofuel --- p.5 / Chapter 1.4 --- Disadvantages of traditional biofuel production --- p.8 / Chapter 1.5 --- Characteristics of microalgae --- p.9 / Chapter 1.6 --- Biofuel from microalgae --- p.14 / Chapter 1.7 --- Nutrients for microalgae related to lipid production --- p.18 / Chapter 1.8 --- Current research on algal biofuel --- p.19 / Chapter 1.9 --- Two phase cultivation as a new way for lipid production --- p.24 / Chapter 1.10 --- Objectives --- p.24 / Chapter 2. --- Biofuel production under two phase cultivation with artificial medium and treated sewage / Chapter 2.1 --- Introduction --- p.26 / Chapter 2.2 --- Materials and Methods --- p.28 / Chapter 2.2.1 --- Algal strains collection and isolation --- p.28 / Chapter 2.2.2 --- Artificial culture media --- p.29 / Chapter 2.2.2.1 --- Bristol’s Medium (BM) --- p.29 / Chapter 2.2.2.2 --- Modified Bold 3N medium (MBM) --- p.31 / Chapter 2.2.3.3 --- F/2 medium (F/2) --- p.33 / Chapter 2.2.3 --- Water quality of treated sewage --- p.33 / Chapter 2.2.3.1 --- Chemical and biological condition --- p.34 / Chapter 2.2.3.2 --- Total organic carbon and total nitrogen (TOC/TN) --- p.35 / Chapter 2.2.3.3 --- Reactive phosphate --- p.35 / Chapter 2.2.3.4 --- Nitrate --- p.37 / Chapter 2.2.3.5 --- Ammonia --- p.39 / Chapter 2.2.3.6 --- Metal elements --- p.40 / Chapter 2.2.4 --- Cultivation conditions --- p.40 / Chapter 2.2.5 --- Growth monitor of microalgae in artificial medium and treated sewage --- p.41 / Chapter 2.2.6 --- Comparison of microalgae cultivated in artificial media and treated sewage --- p.42 / Chapter 2.2.6.1 --- Large scale cultivation --- p.42 / Chapter 2.2.6.2 --- Cell morphology --- p.43 / Chapter 2.2.6.3 --- Cell harvesting --- p.44 / Chapter 2.2.6.4 --- Dried biomass --- p.44 / Chapter 2.2.6.5 --- Lipid content --- p.45 / Chapter 2.2.6.6 --- Fatty acid profile --- p.46 / Chapter 2.2.6.7 --- Extraction of carbohydrates and protein --- p.48 / Chapter 2.2.6.8 --- Carbohydrate content --- p.48 / Chapter 2.2.6.9 --- Protein content --- p.49 / Chapter 2.2.7 --- Two phase cultivation --- p.50 / Chapter 2.2.8 --- Statistical analysis --- p.50 / Chapter 2.3 --- Results --- p.51 / Chapter 2.3.1 --- Water quality of treated sewage --- p.51 / Chapter 2.3.2 --- Nutrient contents in artificial medium --- p.54 / Chapter 2.3.3 --- Growth of microalgae in artificial medium and treated sewage --- p.54 / Chapter 2.3.3.1 --- Cell morphology and cell size --- p.57 / Chapter 2.3.3.2 --- Biomass --- p.59 / Chapter 2.3.3.3 --- Lipid content --- p.61 / Chapter 2.3.3.4 --- Fatty acid profile --- p.63 / Chapter 2.3.3.5 --- Carbohydrates content --- p.66 / Chapter 2.3.3.6 --- Protein content --- p.67 / Chapter 2.3.4 --- Two phase cultivation --- p.69 / Chapter 2.4 --- Discussion --- p.74 / Chapter 2.4.1 --- Water quality of treated sewage and nutrients in artificial medium --- p.74 / Chapter 2.4.2 --- Growth of microalgae in artificial medium and filtered treated sewage --- p.75 / Chapter 2.4.3 --- Microalgae cultivated in artificial media and treated sewage --- p.76 / Chapter 2.4.4 --- Two phase cultivation --- p.81 / Chapter 3. --- Possible toxic effect on algal growth from chemicals in sewage / Chapter 3.1 --- Introduction --- p.84 / Chapter 3.2 --- Materials and methods --- p.85 / Chapter 3.2.1 --- Analysis of dissolved metals by ICP --- p.85 / Chapter 3.2.2 --- Organic compounds --- p.86 / Chapter 3.2.3 --- Algal bioassay --- p.87 / Chapter 3.3 --- Results --- p.88 / Chapter 3.3.1 --- Dissolved metals and metalloids --- p.88 / Chapter 3.3.2 --- Organic compounds --- p.88 / Chapter 3.3.3 --- Algal bioassay --- p.91 / Chapter 3.4 --- Discussion --- p.97 / Chapter 4. --- Conclusion and future prospectives --- p.99 / Chapter 4.1 --- Summary --- p.99 / Chapter 4.2 --- Genetic engineering --- p.100 / Chapter 4.3 --- Further study --- p.102 / Chapter 4.4 --- Conclusion --- p.102 / Chapter 5. --- References --- p.104

Chau, Long Ho. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 73-82). / Abstract also in Chinese. / ABSTRACT --- p.III / 摘要 --- p.IV / PUBLICATIONS CORRESPOND TO THIS THESIS --- p.V / ACKNOWLEDGEMENTS --- p.VI / TABLE OF CONTENTS --- p.VII / LIST OF FIGURES --- p.IX / LIST OF TABLES --- p.XI / ABBREVIATIONS AND NOTATIONS --- p.XII / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.1.1 --- Types of Biofuel Cells --- p.1 / Chapter 1.1.2 --- Properties of Using Enzymes in Bio-energy Generation Systems --- p.2 / Chapter 1.1.3 --- Application of Bio-energy Generation Systems --- p.3 / Chapter 1.2 --- Objectives of the Project --- p.4 / Chapter 1.3 --- Organization of the Thesis --- p.5 / Chapter CHAPTER 2 --- LITERATURE REVIEW --- p.7 / Chapter 2.1 --- Working Principle of a Typical Fuel Cell --- p.7 / Chapter 2.2 --- Introduction of Enzymes and Co-enzymes --- p.9 / Chapter 2.3 --- Functions and Activities of Glucose Dehydrogenase (GDH) --- p.10 / Chapter 2.4 --- Functions and Activities of Laccase --- p.11 / Chapter 2.5 --- Introduction of Carbon Nanotubes (CNTs) --- p.12 / Chapter 2.6 --- Introduction of Gold Nanoparticles (AuNPs) --- p.13 / Chapter 2.7 --- Introduction of PdNPs --- p.14 / Chapter 2.8 --- Summary of Literature Review --- p.15 / Chapter CHAPTER 3 --- WORKING PRINCIPLE OF AN ENZYMATIC BIOFUEL CELL --- p.16 / Chapter 3.1 --- Enzymatic Biofuel Cell Using Glucose as a Fuel --- p.16 / Chapter 3.2 --- Deterministic Factors of the Fuel Cell´ةs Performance --- p.19 / Chapter 3.3 --- Energy --- p.22 / Chapter 3.3 --- Chapter Conclusion --- p.23 / Chapter CHAPTER 4 --- ENZYMATIC BIOFUEL CELL DESIGN --- p.24 / Chapter 4.1 --- Engineering Structure of the EBFC --- p.24 / Chapter 4.2 --- Chemical Structures of the EBFCs --- p.25 / Chapter 4.2.1 --- 1st Structure of EBFC - Au-Ll-CNTs-Ll-AuNPs-L2-{(GDH-NAD)/Laccase} --- p.26 / Chapter 4.2.2 --- 2nd Structure of EBFC - Au-Ll-CNTs-Ll-AuNPs-L2-{GDH/Laccase} --- p.28 / Chapter 4.2.3 --- 3rd Structure of EBFC- Pd-Ll-CNTs-Ll-AuNPs-L2-{(GDH-NAD)/Laccase} --- p.28 / Chapter 4.2.4 --- 4th Structure of EBFC - Pd-Ll -A uNPs-L2-{(GDH~NAD)/Laccase} --- p.29 / Chapter 4.2.5 --- 5th Structure of EBFC- Au-Ll-CNTs~L4'{(GDH-NAD)/Laccase} --- p.30 / Chapter 4.2.6 --- 6th Structure ofEBFC 一 Au-Ll-CNTs-{L3- NAD-GDH/L4-Laccase} --- p.31 / Chapter 4.3 --- Chapter Conclusion --- p.33 / Chapter CHAPTER 5 --- FABRICATION AND CHARACTERIZATION OF EBFCS --- p.34 / Chapter 5.1 --- Materials Preparation --- p.34 / Chapter 5.1.1 --- Preparation of Linker 1 --- p.34 / Chapter 5.1.2 --- Preparation of Linker 2 --- p.35 / Chapter 5.1.3 --- Preparation of Linker 4 --- p.35 / Chapter 5.1.4 --- Purification of Linkers --- p.35 / Chapter 5.1.5 --- Verification of Linkers --- p.36 / Chapter 5.2 --- 3-D Micro Electrode Fabrication --- p.37 / Chapter 5.3 --- Electrode Modification --- p.40 / Chapter 5.3.1 --- 1st Structure of EBFC --- p.40 / Chapter 5.3.2 --- 2nd Structure of EBFC --- p.41 / Chapter 5.3.3 --- 3rd Structure of EBFC --- p.41 / Chapter 5.3.4 --- 4th Structure of EBFC --- p.42 / Chapter 5.3.5 --- 5th Structure of EBFC --- p.42 / Chapter 5.3.6 --- 6th Structure of EBFC --- p.42 / Chapter 5.4 --- Characterization --- p.43 / Chapter 5.4.1 --- Atomic Force Microscopy (AFM) --- p.43 / Chapter 5.4.2 --- Scanning Electron Microscopy (SEM) & Energy-Disperse X-ray Spectroscopy (EDX) --- p.46 / Chapter 5.4.3 --- Cyclic Voltammetry (CV) --- p.47 / Chapter 5.5 --- Chapter Conclusion --- p.52 / Chapter CHAPTER 6 --- RESULTS OF EBFCS --- p.53 / Chapter 6.1 --- Experimental Setup --- p.53 / Chapter 6.2 --- Results --- p.55 / Chapter 6.2.1 --- Results of 1st EBFC --- p.55 / Chapter 6.2.2 --- Results of 2nd EBFC --- p.57 / Chapter 6.2.3 --- Results of 3rd EBFC --- p.58 / Chapter 6.2.4 --- Results of 4th EBFC --- p.60 / Chapter 6.2.5 --- Results of 5th EBFC --- p.60 / Chapter 6.2.6 --- Results of 6th EBFC --- p.65 / Chapter 6.3 --- Chapter Conclusion --- p.67 / Chapter CHAPTER 7 --- CONCLUSION --- p.69 / Chapter 7.1 --- Conclusion --- p.69 / Chapter 7.2 --- Future Work for the Biofuel Cell Project --- p.70 / Chapter 7.2.1 --- Study the Effect of Temperature Change --- p.70 / Chapter 7.2.2 --- Study the Effect of the Change of pH in Substrates --- p.70 / Chapter 7.2.3 --- Further Modified the Electrodes to Enhance the Output Power --- p.70 / APPENDIX --- p.71 / BIBLIOGRAPHY --- p.73

The rapid development of the bioethanol industry globally demonstrates the importance of bioethanol as an alternate energy source to the depleting fossil fuels. To decrease costs and avoid undue pressure on the global food supply, the renewable lignocelluloses appear to be a better substrate for bioethanol production compared to others being investigated. This study investigated the conversion of lignocellulosic material, sugarcane bagasse, to ethanol by the use of Zymomonas mobilis and Pichia stipitis. The investigation of fermentation characteristics of the two strains revealed that their performance on the ethanol production was closely related to the viable cell concentration in the medium. The increase of inoculum size to five fold resulted in an increase in the system co-efficiency to 2.2 fold and 5.2 fold respectively for Z. mobilis and P. stipitis. A theoretical value de (the cell instantaneous ethanol production rate) was introduced to describe the ethanol productivity based on biomass. System co-efficiency proved to be only affected by the viable cell concentration (xC) and de, regardless of ethanol re-assimilation. Immobilized culture of Z. mobilis and P. stipitis showed distinct differences in their characteristics. The bacterium acclimatized to the interior of gel beads; the biomass concentration within the beads increased greater than 10 fold during the reuse of the beads, resulting in an improved fermentation performance. The immobilized P. stipitis gave a similar system co-efficiency level of approximately 0.5 g/l/h under different culture conditions; cell growth in the medium was considerably more vigorous compared to that within the beads. P. stipitis sole-culture on the glucose/xylose medium with a high inoculum size showed a comparable fermentation efficiency with the best result of the co-culture processes. Fermentation of 50.0 g/l of sugar mixture (30.0 g/l glucose and 20.0 g/l xylose) was completed in 20 h with an ethanol yield of 0.44 g/g. No catabolite repression due to glucose was observed for the xylose assimilation. Co-culture of immobilized Z. mobilis and free cells of P. stipitis proved to be the best fermentation scheme on the glucose/xylose sugar mixture co-fermentation. The removal of Z. mobilis after the utilization of glucose improved the stability of the performance. The best result showed that 50.0 g/l sugars were fully converted to ethanol within 19 h, giving an ethanol yield of 0.49 g/g, which is 96% of the theoretical rate. When co-cultured, viable cells of Z. mobilis inhibited the cell activity of P. stipitis, and were capable of growing to high concentration levels without an appropriate carbon source. Acid and enzymatic hydrolysates of sugarcane bagasse showed similar fermentability, but the hydrolysate without overliming significantly inhibited both cell growth and ethanol production of P. stipitis. The co-culture process on the hydrolysate medium successfully utilized 53.56 g/l sugars (32.14 g/l glucose and 21.42 g/l xylose) in 26 h with a yield of 0.43 g/g; this value further increased to 0.49 g/g when ethanol peaked at 40 h. A high cell density proved to be an effective method to improve the system co-efficiency for ethanol production. For the fermentation processes on the sugar medium, results achieved in this study, 10.54 g/l/h for Z. mobilis free cell culture on glucose, 0.755 g/l/h for P. stipitis free cell culture on xylose, 1.092 g/l/h for P. stipites free cell culture on the glucose/xylose mixture and 1.277 g/l/h for glucose/xylose co-fermentation using co-culture, are higher than the best values reported in the literature in batch culture. In the fermentation of the hydrolysate, the system co-efficiency of 0.879 g/l/h achieved with co-culture is comparable to the best values reported for the fermentation of lignocellulosic hydrolysates. / Master of Science (Hons)

Thesis (Ph. D.)--University of Washington, 1983. / Vita. Bibliography: leaves 169-182.

With the global campaign of carbon reduction and sustainable development continue to expand, green environmental conservation has become a vital concern in our modern age. The green energy industry is now very important. The recycling and reuse of fermented organic waste contribute to biomass energy that constitutes a basis for strategies by the green energy industry. In ¡¥Challenge 2008 Six-Year National Development Plan¡XGreen Industry¡XResource Recycle and Reuse Project¡¦, approved by the Executive Yuan and implemented by the Environmental Protection Administration in related policies, a recycle and transport system of household organic waste was established and supported by the efforts of all village and township offices across Taiwan. Diverse developments for the use of biomass energy derived from plants, marsh gas, and organic waste have been achieved through innovative approaches and research among industries, government, and academia. The reuse of organic waste, development of organic fertilizer and livestock fodder, and power generation by marsh gas, and bio-fuels are derivative products of biomass energy. Currently, products made from organic waste have been developed and manufactured in counties and cities all over Taiwan, and related products, such as soil conditioners, organic fertilizers and organic fodder, have been promoted in villages and local communities, forming an excellent green energy cycle and fulfilling the public policy of resource recycle and reuse. Inline with the Green Supply Chain, this study aimed to better understand the measures adopted in the promotion of organic waste in local areas from the perspectives of the concepts regarding the recycling of organic waste and public policy. Through qualitative data collection, including in-depth interviews, focus group and participant observation, this research investigated how the recycling of organic waste can be applied in daily life to reach the target of fully recycling garbage and other waste to improve execution efficiency and how the benefits to the general public who join the efforts can be increased in a relatively simple way.