Screening the environmental sustainability of microbial production of butyric acid produced from lignocellulosic waste streams

Abstract

Butyric acid is a valuable chemical that can be produced from oil or renewable feedstocks. However, due to technological advantages, it is currently synthesised at an industrial level by chemical synthesis. In view of the environmental concerns, attempts to produce butyric acid from renewable raw materials via microbial fermentation have been carried out. One possible route is the production of butyric acid from lignocellulosic feedstocks. This study aims to investigate the environmental profile of butyric acid production from wheat straw. The Life Cycle Assessment (LCA) methodology was applied considering two product formulations: butyric acid in combination with acetic acid (BA1) and butyric acid with high purity (BA2). The functional unit (FU) considered is 1 kg of BA1 and BA2. A sensitivity analysis was performed by considering 100 % renewable energy and using sugar beet pulp and maize stover as alternative lignocellulosic raw materials. The figures show that, when it comes to identify the hotspots of the process, the production of steam, electricity and cellulase cocktail were the main processes with the highest environmental shares for both products, BA1 and BA2. The best environmental profile corresponded to BA1 due to the lower amount of energy and inputs required. The results of the sensitivity analysis reveal that the use of 100 % renewable energy in the production process would significantly reduce the environmental burdens. On the other hand, the use of beet pulp or maize stover as alternatives to wheat straw did not significantly change the global environmental results. This paper shows the importance of applying the LCA methodology to identify possible process improvement alternatives at an early stage of product development.