Comparison of Conventional and Novel Pre-treatment Methods for Bioethanol Production from Fruit and Vegetable Wastes

Tugba Keskin

doi:10.15255/cabeq.2019.1738

Abstract

In this study, novel and conventional techniques for the production of bioethanol from fruit and vegetable wastes (FVWs) by yeast and bacterial fermentation were investigated experimentally. Different pretreatment techniques (acid, heat, acid/heat, and microwave) for yeast fermentation were compared. Maximum ethanol concentrations of 11.7 and 11.8 g L–1 were observed from acid/heat and microwave pretreatment, respectively, by using Saccharomyces cerevisiae. On the other hand, biochar production from FVWs and syngas fermentation from the waste gas of this process were integrated. From waste gas with 12 % CO content, 5.5 g L–1 and 2.5 g L–1 ethanol production was observed by using anaerobic mixed culture and Clostridium ljungdahlii, respectively. The overall results emphasize the potential of bioethanol production from FVWs by economically feasible and environmentally friendly methods.

Highlights

The use of renewable energy sources has gained importance because of the continuous increase in energy needs worldwide due to the constant increase in the global population and industrial activities[1]
That study was performed to determine the effect of formate concentration on ethanol production, and a maximum of 0.45 g L–1 ethanol production was observed, while acetate production values changed between 0.1–0.65 g L–1
Sun et al.[16] used poultry litter for biochar production, and by using the waste gas produced during pyrolysis, they observed a maximum of 12 g L–1 ethanol production

Summary

Introduction

The use of renewable energy sources has gained importance because of the continuous increase in energy needs worldwide due to the constant increase in the global population and industrial activities[1]. Bioethanol can be produced from three different types of organic sources, and 60 % of fuel ethanol is produced via fermentation processes. Since it can reduce the negative environmental impacts of nonrenewable fuel, bioethanol is a very clean alternative. The first group is sugar or molasses, which can be converted to bioethanol without pretreatment by microbial fermentation This technology is easy to apply but the cost of substrate depends on the sugar-producing capacity of countries, which is very limited

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Conclusion