Thermophilic Anaerobic Codigestion of Tomato Pomace and Buffalo Slurry

The buffalo farming and the cultivation of tomatoes for processing are largely spread in Southern Italy. Both produce consistent quantities of waste (sludge and peels plus seeds) raising disposal issues. The work aimed at the identification the optimal inoculum/substrate ratios (ISR) of buffalo sludge (BS) and tomato pomace (TP) for thermophilic anaerobic digestion (50°C). TP extracted from a commercial variety of tomatoes were used in a batch experiment in an Automatic Methane Potential Test System (AMPTS). The glass reactors were fed with BS and TP in four different ISR (3.6, 2, 1, 0.5), based on Volatile Solid (VS) content. The cumulated methane production increased with the reduction of ISR passing from 2.82 (ISR 3.6) to 14.28 (ISR 0.5) NL CH4 L-1. The methane concentration in the biogas was ranging from 67.7% (ISR 0.5) to 84.6% (ISR 3.6). The N-NH3 content significantly increased in the digestate according both to the VS and the methane production, nevertheless remaining below critical level. The results highlighted the potential of the BS/TP codigestion and the synergy that can be obtained with an optimal inoculum/substrate ratio.
Proceedings of the 30th European Biomass Conference and Exhibition, 9-12 May 2022, Online, pp. 765-768