Does seasonality of feedstock affect anaerobic digestion?

Abstract

The feedstock seasonality has been poorly studied in the anaerobic digestion process. The seasonality could disturb the digestion process stability, mainly for fruit and vegetable waste. In this study, three seasonal waste mixtures generated in wholesale markets were reduced to 10, 6, and 4 mm to assess the influence of seasonality and particle size reduction on anaerobic biodegradability. The methane yield ranged between 298 and 465 mL CH4 g VS−1 (volatile solids). Waste mixtures produced in spring at 10-mm particle size presented higher methane production than in autumn/winter and summer, i.e., 32% and 61%, respectively. Methane production decreased with reducing particle size for waste produced in spring from 482 ± 12 to 310 ± 1 mL CH4 g VS−1. In contrast, waste produced in autumn/winter and summer did not show high differences among different sizes. Despite these differences, mixtures with the smallest particle size presented the highest methane production rate. Graphical abstract: [Figure not available: see fulltext.]