In the kraft pulping process, the hemicellulose portion of wood is usually discharged as a waste stream into the black liquor, representing a highly underutilized sugar source. In this study, the hemicellulose prehydrolysate is investigated as a liquid sugar source for production of acetone, butanol, and ethanol by ABE fermentation. For this purpose, hot-water treatment is applied to poplar (hardwood) and southern pine (softwood) for hemicellulose extraction. The acquired hemicellulose prehydrolysate was analyzed to contain, in addition to the carbohydrates in the form of oligosaccharides, various degradation compounds. The toxicity test with model compounds indicates phenolic compounds exert tremendous inhibition on the cell growth. Therefore, detoxification is required prior to fermentation. Adsorption with activated carbon is an effective detoxification method greatly reducing the phenolic content and alleviating the phenol-induced inhibition. Upon detoxification, simultaneous saccharification and fermentation (SSF) of concentrated poplar prehydrolysate with 43.3 g/L sugar produced a total of 10.8 g/L ABE giving a solvent yield of 0.25 g of solvent/g of sugar. Comparatively, SSF of concentrated southern pine prehydrolysate with 46.6 g/L sugar resulted in an ABE production of 13.2 g/L and productivity of 0.28 g of solvent/g of sugar. The details of hotwater-extraction conditions, the performance of detoxification, and the fermentation profiles are discussed. The technical feasibility of utilizing the hemicellulose prehydrolysate as feedstock for biobutanol production has proposed an example of the concept of an integrated biorefinery.
The production of cement involves a combination of numerous raw materials, strictly monitored system processes, and temperatures on the order of 1500 °C. Immense quantities of fuel are required for the production of cement. Traditionally, energy from fossil fuels was solely relied upon for the production of cement. The overarching project objective is to evaluate the use of alternative fuels to lessen the dependence on non-renewable resources to produce portland cement. The key objective of using alternative fuels is to continue to produce high-quality cement while decreasing the use of non-renewable fuels and minimizing the impact on the environment.Burn characteristics and thermodynamic parameters were evaluated with a laboratory burn simulator under conditions that mimic those in the preheater where the fuels are brought into a cement plant. A drop-tube furnace and visualization method were developed that show potential for evaluating time-and space-resolved temperature distributions for fuel solid particles and liquid droplets undergoing combustion in various combustion atmospheres. Downdraft gasification has been explored as a means to extract chemical energy from poultry litter while limiting the throughput of potentially deleterious components with regards to use in firing a cement kiln. Results have shown that the clinkering is temperature independent, at least within the controllable temperature range. Limestone also had only a slight effect on the fusion when used to coat the pellets. However, limestone addition did display some promise in regards to chlorine capture, as ash analyses showed chlorine concentrations of more than four times greater in the limestone infused ash as compared to raw poultry litter.A reliable and convenient sampling procedure was developed to estimate the combustion quality of broiler litter that is the best compromise between convenience and reliability by means of statistical analysis.Multi-day trial burns were conducted at a full-scale cement plant with alternative fuels to examine their compatibility with the cement production process. Construction and demolition waste, woodchips, and soybean seeds were used as alternative fuels at a full-scale cement production facility. These fuels were co-fired with coal and waste plastics. The alternative fuels used in this trial accounted for 5 to 16 % of the total energy consumed during these burns. The overall performance of the portland cement produced during the various trial burns performed for practical purposes very similar to the cement produced during the control burn. The cement plant was successful in implementing alternative fuels to produce a consistent, high-quality product that increased cement performance while reducing the environmental footprint of the plant. The utilization of construction and demolition waste, woodchips and soybean seeds proved to be viable replacements for traditional fuels. The future use of these fuels depends on local availability, associated costs, and compatibility with a facility's p...
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