Impact of pH in the first-stage of a two-stage anaerobic digestion on metabolic pathways and methane production. (December 2022)

• Record Type: Journal Article
• Authors: Gensollen, Gauthier; Pourcher, Anne-Marie; Duedal, Anne-Laure; Picard, Sylvie; Le Roux, Sophie; Peu, Pascal
• Is Part Of: Bioresource technology reports. Volume 20(2022)
• Publication Date: 2022-12
• Subjects: Two-stage anaerobic digester -- Dark fermentation -- Lactose -- Metabolic pathway -- Methane production; Biomass energy -- Periodicals; Biotransformation (Metabolism) -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Waste products as fuel -- Periodicals; Waste products as fuel; Organic wastes; Factory and trade waste; Biotransformation (Metabolism); Biomass energy; Agricultural wastes; Periodicals; Electronic journals; 662.88
• DOI: 10.1016/j.biteb.2022.101256
• Languages: English
• ISSNs: 2589-014X

Abstract

Abstract: The present study focuses on the use of cow manure, slaughterhouse sludge, cheese whey and green beans in a two-stage batch anaerobic process. The effect of pH regulation (4.5 to 7) on metabolic pathways and microbial community involved was studied in the first-stage of the process under mesophilic condition. At a pH lower than 5, fermentation occurred and led to an accumulation of lactic acid with a dominance of Lactobacillus . A pH >5.5 led to dark fermentation. Temporarily lactic acid production was converted in volatile fatty acids. Streptococcus and Enterococcus were involved in lactic conversion at pH 5.5 and 7, respectively. A weak hydrogen production was monitored at these pH ranges. Regardless of fatty acids produced in the first-stage, dark or lactic fermentation did not lead to higher methane production in the second-stage. However, dark fermentation increased methane concentration in biogas from 63.1 % in a single-stage to 83.6 %. Graphical abstract: Unlabelled Image Highlights: Two-stage versus single-stage anaerobic reactor does not impact methane production. The first-stage of the two-stage process at pH ≤ 5 led to lactic fermentation. The first-stage of the two-stage process at pH ≥ 5.5 led to dark fermentation. Dark fermentation in the two-stage process decreases carbon dioxide in biogas.