The effect of thermochemical pretreatment on anaerobic digestion efficiency of municipal solid waste under mesophilic conditions

• Published in: Scientific African 2022-07, Vol.16, p.e01198, Article e01198
• Main Authors: Hajji, A., Rhachi, M.
• Format: Article
• Language: English
• Subjects: Anaerobic digestion; Biogas; Methane; Solubilization; Thermochemical
• ISSN: 2468-2276; 2468-2276
• DOI: 10.1016/j.sciaf.2022.e01198

•The applied pretreatment resulted in a clear improvement in substrate hydrolysis, with the greatest solubilization rate of 65.5%.•The thermochemical pretreatment resulted in an improvement of 180% in biogas production and 19.2% in methane content, compared to the non-pretreated substrate case.•Excess of the alkaline agent NaOH can cause a partial inhibition of the fermentation process. Anaerobic digestion is a promising process with many advantages on the environmental and energy level, yet, it remains little exploited, due to the lack of control of the operating parameters of this process, because of the complexity of the biochemical reactions involved. Among the brakes on the development of this sector, we cite the hydrolysis stage, which is the most kinetically limiting phase of the fermentation process. The present work aims to study the effect of thermochemical pretreatment, at temperatures ranging from 55 °C to 65 °C, with a pH ranging from 8 to 12 and a retention time of 6 to 24 h, on the improvement of substrate hydrolysis, while evaluating the solubilization rate and the biogas yield. The results showed that the applied pretreatment was successful in improving the efficiency of the anaerobic digestion process, by improving the solubilization rate of the substrate, with the greatest rate recorded of 67.1%, which generates a significant increase in the proportion of organic matter that can be converted into biogas. A considerable improvement of the biogas production and the methane rate was noted for all the experiments carried out; the most biogas production of 0.77 mL.g − 1VS, as well as of the methane rate of 68%, was recorded for the pretreatment conditions at a temperature of 65 °C, a pH of 10 and a retention time of 24 h, which is higher by 180% in biogas, and 19.2% in methane, compared to the case of the non-pretreated substrate. [Display omitted]