Subcritical water pretreatment of brewer's spent grains for bio-based products manufacturing in a biorefinery concept

Abstract

Eco-friendly technologies for management of lignocellulosic biomass and generation of biofuels and bio-based products are in constant demand by the industry. Brewer's spent grains (BSG) is the main lignocellulosic by-product generated by the beer industry, accounting for 20 kg per 100 L of beer produced. In Brazil, the generation of BSG is estimated at 2.8×106 ton/year, and BSG is considered in interesting feedstock for application in a biorefinery. However, production of biofuels and other bio-based products from lignocellulosic biomass requires an initial step of pretreatment to overcome the recalcitrance of these materials. In this sense, this project aims to perform experimental assays and an economic analysis of the subcritical water pretreatment (SWP) of BSG for bio-based products manufacturing. For this, the pretreatment of BSG will be conducted in a semi-continuous subcritical reactor to obtain a hydrolysate with high sugar concentration. The hydrolysate obtained will be used as a fermentation medium to produce ethanol, xylitol, and lactic acid. The results obtained in the laboratory experiments will be used to estimate the economic feasibility of the technology, as well as to identify the most profitable option(s) for industrial implementation. Finally, from the techno-economic results obtained, a biorefinery model will be proposed to advance the circular economy of the beer industry.