Selection of additive materials for anaerobic co-digestion of fruit and vegetable waste and layer chicken manure

• All additives increased methane production rate. • Biochars containing redox-active groups favored syntrophic microbial relationships. • Wood pruning waste biochar demonstrated potential for microbial colonization. • Inorganic compounds in fruit and vegetable waste biochar enhanced alkalinity. • The type of biomass for biochar production influenced methane production. This study aimed to assess the potential of different additive materials in enhancing the stability and methane production of anaerobic co-digestion of fruit and vegetable waste and layer chicken manure. A biochemical methane potential assay was conducted to evaluate the co-digestion of substrates with the addition of additive materials (10 g L −1 ): biochars produced (450 and 550 °C) (from fruit and vegetable waste, layer chicken manure, and wood pruning waste), powdered activated carbon, and zeolites. All additive materials increased methane production. Biochars showed better results regarding methane production (increments of 17 to 28 %). The surface of biochars favored the adhesion of microorganisms, this was confirmed by spectra after co-digestion. Furthermore, the redox-active groups in the biochars may have contributed to the microbiological syntrophism, increasing methane rates. These materials are viable for application in co-digestion systems, and the use of waste for their production is an option for solid waste management.