Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nutrition and Food Science, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: leaves 332-370. / by Alejandro Angel Herrero-Molina. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nutrition and Food Science, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by George Costas Avgerinos. / Ph.D.

The objectives of this dissertation’s studies were to determine the effects of different additives on biomass wood pellets’ physical properties and the production energy required to produce each treatment. Chapter II was completed using a pneumatic pelletizer as a small scale test to determine effects of different additives. The pneumatic pelletizer was a good indicator of which additives can be successfully pelletized. The results of this chapter show that using bio-oil can significantly increase calorific value, without significantly decreasing durability and significantly increasing production energy required. Corn starch, in a 4% treatment, was shown to not hinder durability or calorific value significantly, but significantly lower production energy. Biochar was shown to be an additive insignificant in production due to such a low durability. Chapter III is a scaled up pelleting study, which takes additives from Chapter II as well as multiple new additives to determine each one’s effects on the physical properties and production energy effects. The larger scale, Sprout Walden pelletizer gave much different results than that of the pneumatic pelletizer. The results tend to prove beneficial to durability, calorific value, and bulk density with multiple of the treatments. Vegetable oil was a treatment shown to be less beneficial with each increase in additive and would not be recommended in a production setting at such levels. Chapter IV focused on the economic effect of the pellets produced in Chapter III. Equations were made to determine the possible marginal revenue using each of the treatments. The marginal revenue equations take into account the changes in durability and calorific value. Biochar 4%, and vegetable oil at 1% and 2% show that an increase in marginal revenue could be possible with these treatments.

Thesis (M.Sc. (Microbiology)) -- University of Limpopo, 2020 / Bioethanol production from lignocellulosic biomass is seen as an alternative source of energy. However, large-scale production of bioethanol from lignocellulosic biomass is still not feasible due to the high cost of cellulase and lack of cellulases with a high specific activity that can act on crystalline cellulose. The study aimed at screening for microbial cellulolytic enzymes using a proteomic approach. The objectives were to screen for microbial cellulases with a high specific activity and separate the cellulolytic enzymes using a combination of zymography and two dimensional (2-D) gel electrophoresis followed by tryptic digestion, matrix assisted laser desorption ionisation-time of flight (MALDI-TOF) and bioinformatics analysis. Fungal and bacterial isolates were cultured in M9 minimal and Mandel media for a period of 168 hours at 60°C and 30°C with cellobiose and Avicel as carbon sources. Microbial cells were separated from the supernatants through centrifugation and the crude enzymes from the cultures were used for the determination of cellulase activity, zymography, SDS-PAGE and two-dimensional gel electrophoresis. Five isolates, with lytic action on carbon sources studied were a bacterial strain, (BARK) and fungal strains (VCFF1, VCFF14, VCFF17 and VCFF18). Peak cellulase production by the isolates was found to be 3.8U/ml, 2.09U/ml, 3.38U/ml, 3.18U/ml and 1.95U/ml, respectively. Beta-glucosidase zymography resulted in a dark brown band and clear zones against a dark background for endoglucanase. Affinity precipitation of the VCFF17 isolate’s crude enzyme resulted in seven glycoside hydrolases with a carbohydrate binding module (CBM). The presence of the CBM in the glycoside hydrolases produced by the VCFF17 confer the isolate’s potential to be used in the hydrolysis of plant biomass for bioethanol production. Two-dimensional gel protein maps resulted in the separation and quantitative expression of different proteins by the microbial isolates. MALDI-TOF analysis and database search showed that the expressed proteins in this study closely relate to different glycoside hydrolases produced by other microbial species (Hypocrea jecorina, Emericella nidulans, Trichoderma pseudokoningii and Trichoderma koningii). BARK, VCFF1, VCFF14, VCFF17 and VCFF18 showed great potential as cellulolytic enzyme producers for bioethanol production. The BARK isolate exhibited the highest beta glucosidase activity. The isolates studied may benefit the industry in reducing the costs associated with bioethanol production in consolidated bioprocessing system. / National Research Foundation (NRF)

The economic feasibility and energy effectiveness of producing pipeline quality methane gas from biomass was assessed for a new and totally unproven process. The biomass feedstock considered was the common aquatic weed water hyacinth and a novel active boom-winch harvesting system is proposed for its collection. The conversion process analyzed is a two stage biological process which utilizes a leaching-bed for the production of volatile acids and a packed-bed for the production of methane gas. In order to determine the feasibility of the proposed process equipment requirements, capital costs and operating/maintenance costs were developed for three system sizes. This data was analyzed using a life cycle cost model to determine pay back period. The results indicate that payoff period will be less than equipment life and that net energy production occurs. Areas where further research would promote the introduction of this technology are identified and discussed.

The development, testing, and modeling of a multi-fuel biomass combustion system is described. The system is developed by adding air/fuel ratio control and catalytic secondary combustion to a commercially available 150 kW biomass-fueled boiler. The basis of the air/fuel ratio control system is an inexpensive electrochemical oxygen sensor. A catalytic secondary combustion system is developed from monolithic noble metal catalytic combustor segments commonly used on domestic wood burning equipment. The development and understanding of the combustion system is supported by both experimental measurements and theoretical modeling of the combustion process. Experimentally measured variables include gas temperatures, combustion air and exhaust gas flow rates, exhaust gas CO and CO₂ concentrations, and useful heat output. Both equilibrium and chemical kinetic models of the gas-phase combustion process are developed. In the kinetic model, mixing is modeled by assuming the combustion passages behave as a series of perfectly mixed reactors. The modified boiler reduces CO output to about 10 to 15 percent of the CO produced by the baseline unit in steady operation. Results of the combustion modeling indicate that the combustion proceeds nearly to equilibrium except when operating with fuel/air equivalence ratios less than about 0.7 and immediately after addition of a batch of fuel. Under these conditions the gas temperatures are usually low enough to impose a kinetic limit on the combustion process. Equilibrium calculations reveal that more than one-half of the total heat transfer from the combustion products occurs in the combustion zone, indicating that there may be opportunity to reduce kinetic limitations by restricting heat losses from the combustion zone. / Master of Science

Yes / The use of solar thermal energy for water desalination processes is increasing rapidly, particularly in areas where these resources are plentiful. However, solar energy plants are highly affected by the intermittency of day -night cycles and by low irradiation seasons. Although biomass fuel can be used as source of energy for thermal desalination processes, these resources are becoming increasingly scarce, expensive and seasonally available. Integration of solar-biomass technologies for water desalination process may provide the solution to these challenges. This work investigates design options of the Humidification-Dehumidification desalination system integration with the solar-biomass energies. The investigation is based on simulation of the process models in gPROMS platform. Results show that the solar-biomass integrated plant with a thermal storage system can save up to 57 % of the daily energy cost compared to conventional biomass plant. The integrated plant also cuts the CO2 emission by 59 %. Moreover, it has higher daily production capacity than conventional solar plants. / The authors wish to thank the Commonwealth Scholarship Commission in the UK (CSC) for financial support under PhD Scholarships Plan for Low and Middle Income Countries.

This study was undertaken to evaluate the performance of spherical Chinese digesters receiving dairy waste. Sixteen laboratory-scale (3L) reactors were operated in the mesophilic temperature range (35°C±2°C) and were subjected to hydraulic retention times (HRT) of 8, 10, 15, and 20 days and influent substrate concentrations (S₀) of 40.1, 57.8, 62.3, and 71.2 g BVS/L. Preliminary tracer experiments were performed to identify digester flow characteristics. A two-microbial culture mathematical model incorporating incomplete mixing and intermittent feeding was developed to predict effluent quality and gas production. Stimulus-response data indicated that by positioning the outlet at the bottom of the digester, flow characteristics could be improved, leading to reductions in dead space and bypassing volumes by 47% and 91%, respectively. Digesters operated at HRT's of 10, 15, and 20 days performed normally. In these units, for a given S₀, as the HRT was increased the volumetric methane production decreased while the unit methane production increased. The improvement in effluent quality was substantial when the HRT was increased from 8 to 10 days, and was modest when the HRT was increased beyond 10 y days. The 8-day digesters were inhibited due to overloading. pH drops in these digesters were concurrent with alkalinity deficit. The optimum values for operational parameters were found to be an HRT of 10 days, and a loading rate of 7.12 g BVS/L-d. The two-culture mathematical model predicted gas yield and effluent concentration under retarded and normal digester operations. The three-step feed model best described digester activity following feed addition. The sensitivity analysis revealed that the digester model was decreasingly sensitive to the inhibition coefficient of methane-formers (KI2), the inhibition coefficient of acid-formers (KI1), the half-velocity concentrations (KSl, KS2), and the flow-parameters (A, B). / Ph. D. / incomplete_metadata

This dissertation draws on the burgeoning field of innovation of low carbon technologies. Using the functions of innovation systems, this study explores the process of innovation of biofuel ethanol in the U.S. and in Brazil. It uses "process theory" to build a narrative of historical events that represent the innovation trajectory of ethanol biofuel in the U.S. and in Brazil over a period of thirty years. The data is drawn from newspaper articles from the New York Times, Washington Post, and O Estado de Sao Paulo published between 1975 and 2008. Results of this research confirm findings published previously that innovation performs better when the main actors in the innovation process act under clear and well defined policy targets, and when the innovation environment contributes to building positive expectations about the technology. The empirical findings build upon the literature and validate early claims that the alignment of goals between technology producers and users is an inducer of innovation. Moreover, the analysis presented shows that by developing new capabilities, technology users in the downstream market broaden the innovation environment and facilitate the adoption of the emerging technology by new users and markets. For example, the automobile sector has been participating actively in the ethanol technological innovation system in Brazil, facilitating the innovation flow between upstream and the downstream market. This has not been the case in the U.S., where the automobile sector has not found incentives to participate in the ethanol technological innovation systems.

Thesis (Ph. D. - Arid Lands Resource Sciences)--University of Arizona, 1983. / Includes bibliographical references (leaves 164-170).