Solid state anaerobic co-digestion of tomato residues with dairy manure and corn stover for biogas production

• Co-digestion of tomato residues with dairy manure and corn stover.
• Compared to mono-feedstock, co-digestion leads to increased methane production.
• Maximum methane yield of 415.4 L/kg VSfeed was obtained in SS-AD of ternary mixtures.
• More than 40% tomato residues addition caused overproduction of volatile fatty acids.
• Ternary mixtures diluted the inhibitors which caused inhibition in mono-digestion.

Solid-state anaerobic co-digestion of tomato residues with dairy manure and corn stover was conducted at 20% total solids under 35 °C for 45 days. Results showed digestion of mixed tomato residues with dairy manure and corn stover improved methane yields. The highest VS reduction (46.2%) and methane yield (415.4 L/kg VSfeed) were achieved with the ternary mixtures of 33% corn stover, 54% dairy manure, and 13% tomato residues, lead to a 0.5–10.2-fold higher than that of individual feedstocks. Inhibition of volatile fatty acids (VFAs) to biogas production occurred when more than 40% tomato residues were added. The results indicated that ternary mixtures diluted the inhibitors that would otherwise cause inhibition in the digestion of tomato residues as a mono-feedstock.