Abstract

Anaerobic digestion is considered a good method for processing organic waste. The end result is an almost complete conversion of biodegradable organic matter into finished products like methane, carbon dioxide, hydrogen sulphide, etc. The relative proportions of these gases depend on the nature of the fermented substrates and the fermentation conditions. Moreover, these substrates exist in Senegal with potential not yet fully exploited; as an example, Senegal remains the 15th largest exporter of cashew nuts with an annual production of around 18,000 tons. Kolda, Ziguinchor, Sédhiou and Fatick are the main producers of cashew apples. Thus, each year, after the cashew nut campaign, more than 342,000 tons of cashew apples, pressed or not, are rejected without being valued, and therefore doomed to rot. This work aims to characterize the anaerobic digestion of cashew apples in the presence of inoculum, with a prior pretreatment of the apple. The physico-chemical characterization shows that the cashew apple essentially contains 98.81% organic matter with a C/N ratio equal to 23.27%. The carbon content was determined by an empirical method and that of nitrogen by the Kjeldahl method. The biogas produced is composed of 63.60% methane and 32.71% carbon dioxide.

Key words: Anaerobic digestion, cashew apple pulp, inoculum, biogas.