Co-digestion of wheat and rye bread suspensions with source-sorted municipal biowaste. (June 2015)

• Record Type: Journal Article
• Authors: Li, Chaoran; Mörtelmaier, Christoph; Winter, Josef; Gallert, Claudia
• Is Part Of: Waste management. Volume 40(2015)
• Page Start: 63
• Page End: 71
• Publication Date: 2015-06
• Subjects: Biowaste suspensions -- Rye or wheat bread suspensions -- Co-digestion -- Microbial community changes; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2015.03.024
• Languages: English
• ISSNs: 0956-053X

Abstract

Graphical abstract: Volatile fatty acid spectra of acidified WBS, RBS or FBS differ, but methanogenesis is similar. Highlights: Biogas improvement by co-digestion of wheat and rye bread. Increased population density at high organic loading rates. Less Pelotomaculum but increased numbers of Syntrophobacter and Smithella found in rye bread reactor. Replacement of Methanosarcinales by acetate-oxidizers in rye bread co-digestion. Increasing proportion of Methanomicrobiales in biowaste + rye bread reactor. Abstract: Acidification of wheat bread (WBS), rye bread (RBS) and fresh biowaste suspensions (FBS), leading to lactate+acetate, lactate+acetate+n-buyrate, and acetate+propionate+n-butyrate, respectively, and biogas production as well as population dynamics were investigated. Co-fermentation of FBS (14 kg m −3 d −1 organic loading rate (OLR)) with WBS or RBS was stable up to an OLR of 22 kg m −3 d −1 and resulted in up to 3 times as much biogas. During co-fermentation at more than 20 kg m −3 d −1 OLR the total population increased more than 2-fold, but the originally low share of propionate-oxidizing bacteria significantly decreased. The proportion of methanogens also decreased. Whereas the proportion of Methanosarcinales to Methanomicrobiales in biowaste and biowaste+WBS remained constant, Methanosarcinales and in particular Methanosaeta spec. in the biowaste+RBS assay almost completely disappeared. Methanomicrobiales increased instead, indicating propionate oxidation via acetate cleavage to CO2 and hydrogen.