Techno-economic evaluation of anaerobic co-digestion of pepper waste and swine manure

Agro-industrial waste represents a major challenge for the environment. Among these, the processing of peppers generates a large amount of waste, so the search for new ways to valorise this waste is crucial. This work aims to assess the use of pepper waste for methane production with swine manure. During this study, anaerobic co-digestion was evaluated in both batch and semi-continuous operation. Specifically, batch assays were performed following a factorial design to study the effect of the initial substrate concentration and the percentage of pepper waste on methane yield and on volatile solid removal. In these assays, the highest specific methane yield was 309 NmL g VS-1 obtained at 2.5 g VS L-1 and 50% of pepper waste in the feed. Under semi-continuous operation, anaerobic co-digestion improved the methane yield up to 86% in comparison to the mono-digestion of swine manure. In addition, the economic assessment showed the viability of the process with positive indices of the anaerobic co-digestion of pepper waste and swine manure. These results proved that the anaerobic co-digestion of these substrates can be a technically and economically viable alternative for its valorisation.