Immobilization ofSaccharomyces diastaticus on wood chips for ethanol production

Abstract

Saccharomyces diastaticus cells were immobilized onto beech wood chips of different particle size and three pH values. pH values in the range 5.0-6.0, and 1.84-1.92 mm particle size had a positive effect on the immobilization process. The chosen carrier--1.84 mm-sized wood chips adsorbed 150 mg dry cell mass per g dry carrier mass. The Gibbs free energy and the activation energy for the first (monolayer) and second (multilayer) immobilization stages was 4581, 19,090 and 8590 J g mol-1, respectively. The kinetics of immobilized cell systems in ethanol production have been studied in a packed bed-reactor. Ethanol production and the respiration quotient (RQ) were at a maximum at a dilution rate of 0.16/h. The reactor was operated under steady-state conditions for 30 d at the dilution rate 0.16/h.

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“…Cell loads expressed as a number of cells per carrier weight (volume of reactor) given by other authors were converted into mg dry cell g −1 dry carrier (ml rector volume) considering the diameter of the brewing yeasts 8 µm, their water content 70% (v/v) and density close to water (Alberts et al 1994). The yeast cell load value closest to those in the present work was found for beech wood chips as a carrier for ethanol fermentation (150 mg dry cell g −1 d.c.) where authors also referred about multilayer immobilisation (Razmovski & Pejin 1996). The higher cell load presented in our work can be ascribed to the significantly lower average size range of our carriers (0.8-0.3 mm) than was the size of the wood chips (1.84 mm).…”

Ethanol fermentation of molasses by Saccharomyces cerevisiae cells immobilized onto sugar beet pulp

“…However, technically it is less suitable for ethanol production because the growth of the yeast cells is restrained and also the slowly growing yeast cells are difficult to be removed from the systems (2). However, the use of yeast immobilized by natural adhesion onto low-cost plant materials such as wood chips (7), apple peaces (8), orange peel (9), sugar cane bagasse (10), sugar cane pieces (11), corn cobs and grape pomace (12) and maize stem ground tissue (13), can effectively overcome these drawbacks. Yeast cells immobilization by adhesion onto the solid supports is attractive in ethanol fermentation, due to the operational easiness and high ethanol productivity, thanking to the effective retention of cells within the bioreactor.…”

Progress in the production of bioethanol on starch-based feedstocks

“…Among this approach, the most explored are immobilization of yeasts in/on adequate matrices such as calcium alginate, k-carragenan gel, polyacrylamide-alumina [40,48,79,80,88], wooden chips [89], PVA gel [90], orange peel [91], etc. Among this approach, the most explored are immobilization of yeasts in/on adequate matrices such as calcium alginate, k-carragenan gel, polyacrylamide-alumina [40,48,79,80,88], wooden chips [89], PVA gel [90], orange peel [91], etc.…”

“…tually enable reuse [48,[79][80][81][82][83][84][85][86][87][88][89][90]. For this purpose Rakin et al applied immobilization in two biocompatible polymers such as: PVA and Ca−alginate [90] demonstrating that the PVA exhibited better mechanical properties and stability in repeated use, while Ca-alginate immobilized yeast gave higher ethanol yields, most probably due to lower mass transport restricttions.…”