Effect of combined mechanical–ultrasonic pretreatment on mesophilic anaerobic digestion of household organic waste fraction in Morocco

Abstract

Methanization is a technology that involves complex biological reactions and it is the subject of several scientific studies. The paper aims to evaluate the effect of the combined mechanical and ultrasonic pretreatment (CMUP) on the anaerobic digestion (AD) of the household organic waste fraction in Morocco (HOWF), using a continuous stirred tank reactor (CSTR) at mesophilic conditions.This article presents and compares a results obtained by operating two experiments in lab scale reactors with mechanical pretreatment (MP) and with CMUP. The experiment with MP was considered in this study as a control. During the handling period, the effect of CMUP on the AD of HOWF was studied. The process was evaluated in terms of methane production and biodegradability. The stability was maintained within correct parameters throughout the process for each experiment, while the methane yield and biodegradability of the control and CMUP experiments were 382 (mL CH4 g−1VS) (0°C, 1 atm), 72%, and 493 (mL CH4 g−1VS) (0°C, 1 atm), 86 % respectively. This shows clearly that the CMUP enhance the methane production and increase the biodegradability, suggesting that this combination pretreatment improve the hydrolysis and methanogenesis phases of the process.A kinetic study on anaerobic digestion results using the first order model was also used. The mathematical model shows a good fit with the experimental data. Keywords: Anaerobic digestion, HOWF, Mechanical pretreatment, Ultrasonic pretreatment, Methane yield, Biodegradability