Can the seasonal variability affect the BMP of fruit and vegetable waste?

Fruit and vegetable waste (FVW), largely produced in open markets, is characterized by highly putrescible materials, thus being a proper substrate for anaerobic digestion. This study investigated the effect of the seasonal variation of FVW, on the biochemical methane potential (BMP). To this end, FVW with an average composition between the wastes collected from open markets in Amman (Jordan) and Sfax (Tunisia) was considered. Three sets of batch BMP tests were carried out using three seasonal FVW compositions under mesophilic conditions (34°C). The selected fruits and vegetables were chopped until reaching a particle size of 10 mm. Sewage sludge was used as inoculum, and the batch experiments were performed with an inoculum/substrate ratio of 2 (g VS basis). VFAs, TS and VS content, COD, TAN, pH and alkalinity were monitored. Results show a final methane yield of 493.1 ± 27.7, 394.2 ± 69.6 and 373.3 ± 32.4 NmL CH4 g SV-1 for the winter, spring and summer composition, respectively. Due to the high biodegradability of all substrates, more than 80% of the total methane production occurred in the first 7 days, with a simultaneous reduction of the soluble COD and VFAs. For the highest performing substrate, a 40% reduction of VS was observed.