Sustainable management of spent coffee grounds: applications, decompositions techniques and structural analysis

Spent coffee grounds is considered as one of the most common biomass waste globally. The sources of spent coffee grounds being classified as domestic, commercial and industrial. Currently, landfills are the unsuitable destination for the majority of the produced spent coffee grounds and this permits anaerobic breakdown of spent coffee grounds, which produces and releases strong greenhouse gases as a result. Consequently, a wide range of potential uses for discarded coffee grounds and their by-products are being investigated by researchers worldwide, including biofuels, adsorbent, catalysts, cosmetics, composite materials, feed and many more. Spent coffee grounds are rich in carbohydrates, lipids, proteins and minerals. As a result, research focus is on using it in a variety of applications. The review adopts a whole system to summarize up to date knowledge of different methods of thermal breakdown of spent coffee grounds for producing verities of valuable products. Essential processes under this study included, comparative analysis of various thermal decompositions methods, material’s behavior and characteristics evaluation based on thermal treatment and its respective applications, which have often been overlooked in prior reviews.