Evaluation of process parameters in the production of ethanol from agricultural waste

Abstract

The effect of temperature at which hydrolysis took place, hydrolysis and incubation times on percentage yield of ethanol using sawdust as biomass was investigated in this study. The collected sawdust was pretreated by soaking it in NaOH for 2 h and then boiled for 1 h at a temperature of 100°C. Enzymatic hydrolysis was thereafter carried out on the pretreated substrate by varying hydrolysis temperature (30-40°C), hydrolysis time (60-300 min). Thereafter, Saccharomyces cerevisiae was used for saccharification and fermentation which took place concurrently at varied incubation time (1-5 days). Box-Behnken design (BBD) in response surface methodology (RSM) using Design-Expert software was used to model and optimize the yield of ethanol using the selected process parameters. The production of ethanol from sawdust was positively influenced by all three process parameters. The optimum ethanol yield was 2.247 % at hydrolysis temperature, hydrolysis time, and an incubation time of 41.642 °C, 199.184 min and 3.546 days respectively. The very close values of the ethanol yields by the model and by the actual experiment performed at the optimal conditions validated the model.