Browsing by Subject "Carboxylic Acids"
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Item Continuous fermentation of food scraps with constant pH control to produce carboxylic acids(2009-05-15) Coleman Jr., Stanley AlbertGlobal energy demands combined with environmental restrictions are fueling a move to alternative energy sources. Biofuels are formed from biomass; the MixAlco process is one such method. In this work, food scraps are explored as a potential feedstock to the MixAlco process. Batch fermentation with various temperatures, buffers, and pH control methods elucidated the behavior of food scraps during fermentation. The pH and reactor configuration were limiting factors when maximizing production. A fermentor was developed and tested with constant pH control. This resulted in elevated concentration (100 g/L) and selectivity (82%) of desired products. The fermentation resulted in elevated concentrations, but low conversion of solids. The undigested material may serve as a nutrient source for fermenting lignocellulosic feedstocks. Combining various nutrient sources with lignocellulose, such as bagasse, resulted in additional production and further conversion. Multiple nutrient sources were tested resulting in total acid concentration ranging from 20.2 to 34.5 g/L.Item Pilot-scale fermentation of office paper and chicken manure to carboxylic acids(Texas A&M University, 2006-08-16) Moody, Andrew GarretThis project focused on scaling up the laboratory fermentation of biomass to carboxylic acids. Four 1050-gallon tanks were used to simulate four-stage countercurrent fermentation. Most laboratory fermentations have been performed with 1-L fermentors. The purpose of the pilot plant was to show that the process is scalable. The inocula were marine and terrestrial microorganisms. Office paper was used as an energy source, and chicken manure provided the necessary nutrients. The substrate was 80 wt% office paper and 20 wt% chicken manure. Calcium carbonate was used as a neutralizing agent and iodoform served as a methane inhibitor. The fermentor temperature was 40 oC and the pH was 6.0. The highest total acid concentration obtained was 32.4 g/L, operating with a volatile solids loading rate (VSLR) of 1 g/(L liq ??d) and a liquid residence time (LRT) of 80 days. Typical laboratory VSLRs and LRTs are 3 to 10 g/(L liq ??d) and 10 to 30 days, respectively. Similar VSLRs and LRTs were not achieved at the pilot scale because the design was limited by the ability to effectively separate large amounts of solids and liquids. The bulk of the effort was concentrated on overcoming temperature control and solids-handling issues. Design modifications included a redesigned temperature control system and a new material transfer method.