Subcritical hydrolysis and anaerobic digestion for the production of sugars and biogas from apple pomace from juice processing

Abstract

The demand for technologies for converting biomass and reusing waste has put pressure on the industrial products sector to increasingly invest in innovations aimed at generating new products with high-energy use. In this context, subcritical water technology is recognized as a clean and sustainable process for obtaining bioactive compounds and sugars from byproducts of plant matrix processing and dry anaerobic digestion, which values wastewater and solid waste for the biogas production. Therefore, the development of processes that further enhance solid waste's technological characteristics has received much attention from the global production sector. Based on this scenario, this project's objective is to use an integrated system of subcritical hydrolysis and anaerobic digestion to treat solid residues from the apple processing industry (Malus domestica), aiming the production of high added value sugars and biogas. The pectin extraction also will be analyzed. The pre-treatment of apple pomace by hydrolysis with subcritical water will be evaluated for the production of xylose, arabinose, fructose, and others. The biochar obtained after the hydrolysis step will be evaluated as adsorbent material in an adsorption column for the 5-hydroxymethylfurfural and furfural fermentation inhibitors. The operation of the anaerobic bioreactor using the hydrolyzate as a substrate will result in biogas production. All the processes used in obtaining the co-products will be evaluated technically and economically. Therefore, the integration of these technologies can contribute to the decarbonization of the energy matrix, support the transition to a circular economy, based on the reduction, reuse, recovery, and recycling of energy, with environmental, social, and economic benefits for the local and regional sustainable development. (AU)