Bacterial dynamics during the anaerobic digestion of toxic citrus fruit waste and semi-continues volatile fatty acids production in membrane bioreactors. (1st July 2022)

• Record Type: Journal Article
• Authors: Awasthi, Mukesh Kumar; Lukitawesa, Lukitawesa; Duan, Yumin; Taherzadeh, Mohammad J.; Zhang, Zengqiang
• Is Part Of: Fuel. Volume 319(2022)
• Publication Date: 2022-07-01
• Subjects: Bacterial community -- Volatile fatty acids -- Citrus waste -- Anaerobic digestion; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2022.123812
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: Bacterial diversity reduced (49158–65239) after anaerobic digestion of citrus waste. The key bacterial phylum affiliated to Firmicutes (37.35–84.73%). Treatment POLR8 has greatest abundance of acid forming bacterial (84.37%). Treatment UOLR4 has greater acid utilizing bacteria (70.09%). Organic loading rate 4 g VS/L⋅d is feasible way to produce volatile fatty acids. Abstract: Citrus wastes (CW) are normally toxic to anaerobic digestion (AD) because of flavors such as D-limonene. In this study, bacterial community was evaluated during volatile fatty acids (VFAs) production from CW inoculated by sludge in a membrane bioreactor (MBR) using semi-continuous AD with different organic loading rates (OLR). Four treatments including untreated CW filled with 4 and 8 g·VS·L −1 d −1 OLR (UOLR4 and UOLR8), pretreated D-limonene-free CW filled with 4 and 8 g·VS·L −1 d −1 OLR (POLR4 and POLR8). The initial inoculum and the CW mixture (DAY0) was used as control for comparison. There was an obviously higher bacterial diversity in raw material (66848 sequences in DAY0), while decreased after AD and higher in POLR4 and POLR8 (65239 and 63916) than UOLR4 and UOLR8 (49158 and 51936). The key bacterial associated with VFAs production mainly affiliated to Firmicutes (37.35–84.73%), Bacteroidetes (0.48–36.87%), and Actinobacteria (0.35–29.38%), and the key genus composed of Lactobacillus, Prevotella, Bacillus, Bacteroides and Olsenella which contributed in VFA generation by degradable complex organic compounds. Noticeably, methanogen completely suppressed after MBR-AD and UOLR4 has greater acid utilizing bacteria (70.09%).