Digestate: a systematic review of its sources, treatments and industrial applications

Abstract

Digestate, a byproduct of anaerobic digestion, presents growing potential for industrial applications derived from organic and industrial waste. However, its use is still limited due to variability in its composition, which affects its quality and suitability for reuse. This systematic literature review aims to identify and analyze the most effective treatment methods applied to digestate, considering its source and potential uses in various industries. A total of 1,366 documents published in the last five years were retrieved from the Scopus database. After applying defined inclusion and exclusion criteria through a structured screening process, 51 open-access articles were selected for in-depth analysis. The findings reveal that the most commonly applied treatments are solid-liquid separation, hydrothermal carbonization, and membrane technologies. These methods enhance digestate manageability, reduce pathogens, and enable carbon capture or nutrient recovery. The most frequent feedstocks include pig and cattle manure, agricultural residues, and sewage sludge, with predominant applications in the agricultural sector as fertilizers or soil amendments. Some cases also demonstrate energy recovery potential due to the digestate's carbon content. In conclusion, digestate when adequately treated can play a critical role in advancing industrial sustainability and promoting a circular economy by transforming organic waste into valuable resources.