Life cycle analysis of fermentative production of succinic acid from bread waste

Siddharth Gadkari,Deepak Kumar,Zi-Hao Qin,Carol Sze Ki Lin,Vinod Kumar

doi:10.1016/j.wasman.2021.04.013

Abstract

According to the US Department of Energy, succinic acid (SA) is a top platform chemical that can be produced from biomass. Bread waste, which has high starch content, is the second most wasted food in the UK and can serve as a potential low cost feedstock for the production of SA. This work evaluates the environmental performance of a proposed biorefinery concept for SA production by fermentation of waste bread using a cradle-to-factory gate life cycle assessment approach. The performance was assessed in terms of greenhouse gas (GHG) emissions and non-renewable energy use (NREU). Waste bread fermentation demonstrated a better environmental profile compared to the fossil-based system, however, GHG emissions were about 50% higher as compared to processes using other biomass feedstocks such as corn wet mill or sorghum grains. NREU for fermentative SA production using waste bread was significantly lower (~ 46%) than fossil-based system and about the same as that of established biomass-based processes, thus proving the great potential of waste bread as a valuable feedstock for bioproduction of useful chemicals. The results show that steam and heating oil used in the process were the biggest contributors to the NREU and GHG emissions. Sensitivity analyses highlighted the importance of the solid biomass waste generated in the process which can potentially be used as fish feed. The LCA analysis can be used for targeted optimization of SA production from bread waste, thereby enabling the utilization of an otherwise waste stream and leading to the establishment of a circular economy.

Highlights

The non-renewable nature of fossil fuels and their negative impact on the environment has necessitated the search for alternative, sustainable, and environment friendly routes, based on the use of renewable feedstock
The objective of this study is to evaluate the environmental performance of fermentative succinic acid (SA) production using waste bread as feedstock, where fermentation is carried out using A. succinogenes and the productivity and yield values are directly calculated based on the weight of the feedstock
Heating oil is the second biggest contributor to greenhouse gas (GHG) emissions with 0.14 kg CO2 eq, which is about 11% of the total GHG emissions produced from the process

Summary

Introduction

The non-renewable nature of fossil fuels and their negative impact on the environment has necessitated the search for alternative, sustainable, and environment friendly routes, based on the use of renewable feedstock. In addition to being a significant loss of valuable materials, these enormous quantities of waste result in serious management problems, both economically and environmentally Most of this highly perishable food waste forms a significant part of the municipal solid waste, which leads to bad odour, creates air pollution, contaminates ground water, and serves as a breeding ground for pathogenic microbes (FAO, 2012; Kumar and Longhurst, 2018). This problem of food waste has been intensified due to the slow progress made in the development of efficient technologies for waste treatment and disposal

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