(718e) Simultaneous Pretreatment, Saccharification, Fermentation and Separation Processes to Obtain Ethanol

Carvajal, J. C. - Presenter, Universidad Nacional de Colombia
Daza, L. V., Universidad Nacional de Colombia
Aristizábal, V., Universidad Nacional de Colombia
Cardona, C. A., Universidad Nacional de Colombia

Lignocellulosic biomass (LB) is nowadays an important raw material due to its contents of cellulose, hemicellulose and lignin and that can be used to obtain high value-added products. The Sisal (Furcraea andina) is the main existing natural fiber in Colombia with an annual demand of approximately 30,000 tons. In addition, Colombia is the largest producer of this material at Worldwide. According to the available harvested sisal, there is approximately 5100 tons per year of sisal bagasse, where each ton processed, approximately 70% is juice, 5% fiber and 17% bagasse. For this reason it could be considered us a potential raw material for the production of high value-added products.

To produce ethanol from lignocellulosic materials its required mainly three steps that involves pretreatment, fermentation and separations operations. In the pretreatment stage the degree of polymerization and crystallinity reduction of lignocellulosic material are the principal objectives. The improvement of cellulose available in the surface area and lignin matrix destruction can be performed by hydrothermal, acid, alkaline and organosolv pretreatments [1]. These conventional operations lead the presence of inhibitors that could directly affect the fermentation yields and the behavior of the microorganism. In the fermentation stage some microorganisms could be inhibited by high concentrations of substrate and products. Due to its possible inhibition scenarios some investigations has worked in simultaneous saccharification and fermentation schemes with aim to overcome the inhibitory barriers [2]. Other approach that has been developed to avoid the inhibition by product formation using the extractive fermentation. This method liquid-liquid extraction or immiscible extraction in a fermented vessel. There are  several investigations focused on the separation of lactic acid as example by extractive fermentation evaluatingthe use of different solvents as quaternary amines, tertiary amines, secondary amines and quaternary ammonium salts , among others [3] [4] [5].

In this work the pretreatments studied were fine milling and ammonia with ligninolytic enzymes as laccase to analyze their effects on the ethanol yields production. There alternatives for the pretreatment of lignocellulosic were simultaneously coupled with saccharification, fermentation and separation using ethylene-glycol [6][7][8] as solvent of liquid.liquid extraction.

Sisal bagasse was experimentally characterized by measuring moisture content (AOAC 928.09 method), Klason lignin content (TAPPI 222 om-83 method), acid-soluble lignin content (TAPPI 250UM-85 method) holocellulose content (ASTM Standard D1104 method), cellulose content (TAPPI 203 os-74 method), and ash content (TAPPI Standard T211 om-93 method). Then three different schemes were experimentally evaluated in the 1 liter bioreactors and reactive extraction system with disk (5 liters) in the Biotechnology and Agroindustrial Institute at Universidad Nacional de Colombia at Manizales.

The ethanol production through the formulated schemes was then evaluated using the commercial software Aspen Plus V8.0 (ASPEN TECHNOLOGY INC). The first scenario was evaluated for ethanol production in which all the stages are continuously followed. The second scenario includes ethanol production using a simultaneous approach. The economic evaluation was performed using the software commercial Aspen Process Ecomomic Analyzer V8.0 (ASPEN TECHNOLOGY INC) taking into account the Colombian context with an annual interest rate of 16% and an income tax of 25%, with electricity and water costs according to the case study conditions. Furthermore, the evaluation was realized for a period of 10 years using as depreciation method the straight-line. As a main result, the proposed integration has worked well for the sisal fiber as raw material in comparison to separated processes.


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