No abstract

Purpose 3Local open markets, trading fruits and vegetables, are widespread in Mediterranean 4 countries, such as Tunisia and Jordan, producing large amounts of organic waste. 5Applying an anaerobic digestion process on this substrate makes it crucial to evaluate 6 the waste mixture composition and seasonal variability properly. In this study, after 7 defining an average composition of the fruit and vegetable waste (FVW) mixture 8 produced in Sfax (Tunisia) and Amman (Jordan) in three seasonal intervals (autumn-9 winter, spring, and summer), the biochemical methane potential (BMP) of an 10 artificially created FVW mixture was individually determined by three European 11 institutions located in Spain, Italy, and Greece. The average BMP from all three 12 seasons and laboratories was 286±52 NmL CH 4 g COD added -1 , close to the theoretical 13 maximum yield of 350 NmL CH 4 g COD added -1 , indicating a high biodegradability of 14 the waste. Τhe biochemical methane yields of the spring mixtures were not 15 statistically different across the three labs. The most significant differences among the 16 BMP results were obtained for the autumn/winter and the summer mixtures used in 17 Spain, likely due to the variety or ripeness of fruits and vegetables collected in the 18 local markets. In the other two labs in Italy and Greece, no statistical difference was 19 observed for the BMPs of the three season mixtures within the same lab. Therefore, 20 not a critical difference in the biodegradability of such FVW is expected along the 21 different seasons, indicating that the operation of a full-scale digester over a whole 22 year would constantly benefit from the supplementation of a high biochemical 23 methane potential feedstock.