The acid hydrolysis of paper to fermentable sugars and the subsequent fermentation of the sugars to ethanol

Anderson, Judith (1981). The acid hydrolysis of paper to fermentable sugars and the subsequent fermentation of the sugars to ethanol. MPhil thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000fcce

Abstract

The process of hydrolysing the cellulose content of various waste materials to sugars was first utilised in Germany prior to World War II to counteract the industrial ethanol shortage which existed during that period. Now as the anticipated shortage of vital energy-producing fossil sources becomes more apparent, cellulose is once again recognised as an important potential source.

A bench scale rig has been designed to effect the chemical hydrolysis of cellulose at high temperature (230oC) and pressure (3.4x106 Pa) with 1-2% sulphuric acid as a catalyst. The rate of conversion to sugars is a function of temperature and pH, and a screening and optimisation exercise of these variables has been undertaken. The yields of sugars achieved ranged from 0.4% to 30% conversion (glucose equivalent).

The sugars formed were collected, neutralised and used for fermentation tests. These were carried out using Saccharomyces cerevisiae and certain bacteria in pure and two-member batch and continuous cultures to produce ethanol. Analyses of yields, specific growth and production rates and concentrations were made, with which knowledge, comparison could be made between the performances of the various organisms on the hydrolysis sugars, under specified conditions. S. cerevisiae performed well in hatch and continuous cultures and yields of ethanol near the theoretical maximum were achieved. Of the bacteria Aerobacter aerogenes gave a similar performance in continuous culture. The other two, Pseudomonas saccharophila and Bacillus polymyxa gave low yields and hindered the activities of the yeasts in two-member cultures.

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