Ethanol Production Thesis

Ethanol Production Thesis-57
These raw materials are sufficiently abundant and also available world-wide.They generate very low net greenhouse gas emissions, thus reducing environmental impacts.

To achieve systems that are economic and sustainable it is necessary to efficiently utilize all parts of the raw materials, mainly cellulose, hemicellulose and lignin.

This requires a high overall yield of ethanol produced by hydrolysis and fermentation of the carbohydrate fraction (hemicellulose and cellulose), as well as a high yield of the main co-product (lignin).

In conclusion, this work defines a successful microbial system that is able to efficiently utilize lignocellulosic material as a carbon source and a translocant yeast strain that has high level of cellulase activity.

These details should be considered as only a guide to the number of downloads performed manually.

Some of the most important factors to reduce the production cost are: efficient utilization of the raw material by high ethanol yields, high productivity, high ethanol concentration in the feed to distillation and process integration in order to reduce capital cost and energy demand.

The key steps for success are the conversion steps, i.e.However, the process concept has not yet been demonstrated on an industrial scale.GALBE, Mats; ZACCHI, Guido; "PRODUCTION OF ETHANOL FROM LIGNOCELLULOSIC MATERIALS", p. In: Sugarcane bioethanol — R&D for Productivity and Sustainability. pretreatment, enzymatic hydrolysis and fermentation (or SSF) of all sugars.It is also crucial to have a highly integrated process working at high consistency to minimize the energy demand in the downstream processing, e.g. Pilotscale production plants and pre-commercial demonstration facilities have recently been brought into operation in several places world-wide3, 4, 5, 6.Ethanol production from lignocellulose comprises the following main steps: hydrolysis of hemicellulose, hydrolysis of cellulose, fermentation, separation of lignin, recovery and concentration of ethanol and wastewater handling, see Figure 1.A process based on enzymatic hydrolysis and fermentation is currently regarded as the most promising option for the conversion of carbohydrates in lignocellulosic materials into ethanol in an energyefficient way, resulting in high yields and low production cost1, 2.The first part of the study deals with bioethanol production from lignocellulosic material by microbial fermentation in two steps.The first step is the degradation of the lignocellulosic material by Bacilli to produce cellobiose, and the second step is to convert cellobiose into glucose by a B-glucosidase expressing recombinant yeast strain.As lignocellulosic material, wood powder from industrial waste was used and the degradation of the wood powder into glucose was confirmed by following the growth curve of the microorganisms and through appropriate enzymatic assays.The second part of the study utilizes two novel technologies, Yeast Artificial Chromosome (YAC) and Bridge-Induced Translocation (BIT) to introduce new, multi-factorial genetic traits into a yeast strain, a process that would otherwise take several time-consuming and labor-intensive rounds of genetic engineering.


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