Organic overloading affects the microbial interactions during anaerobic digestion in sewage sludge reactors. (May 2019)

• Record Type: Journal Article
• Authors: Braz, Guilherme H.R.; Fernandez-Gonzalez, Nuria; Lema, Juan M.; Carballa, Marta
• Is Part Of: Chemosphere. Volume 222(2019)
• Page Start: 323
• Page End: 332
• Publication Date: 2019-05
• Subjects: Anaerobic microbiome -- Glycerol -- Methanosaeta -- sludge digestion -- Veillonellaceae.; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.01.124
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: There is still a lack of information about microbial interactions of anaerobic digestion microbiome during process disturbance which limits our ability to predict the mechanisms that drive community dynamics on these events. This paper aims to determine how an organic overloading affects these interactions and to characterize in detail the microbiome structure and diversity in sewage sludge anaerobic reactors during an acidosis event. Two identical sewage sludge anaerobic reactors were subjected to an organic loading shock by adding glycerol waste. As consequence, volatile fatty acids accumulated after only 24 h (up to 2.5 g/L) while Bacteroidales and Methanomicrobiales became displaced by Firmicutes and Methanosaeta sp, showing that reactor acidosis can occur without an immediate decline of this methanogen. Network analysis revealed 9 clusters of co-occurring microorganisms with different behaviors during overloading. At first, Veillonellaceae family, the main glycerol degrading, associated with Candidatus Cloacimonetes, volatile fatty acids fermenters, increased their relative abundance in detriment of the syntrophic bacteria; although as conditions become more acidic, these groups were displaced by other fermenters like Porphyromonadaceae and Chitinophagaceae. Eventually, the methanogenesis failed 72 h after organic overloading, when pH reached values lower than 6. Overall, our results showed a succession of functionally redundant microorganisms, most likely because of niche specialization during organic overloading. The detailed temporal analysis elucidated the processes governing the dynamics anaerobic digestion microbiome, a knowledge required to develop anaerobic digestion management strategies based on its microbiome during process disturbances. Highlights: Operational parameters similarly varied after few hours of organic overloading in replicated reactors. Methanosaeta sp. incremented with increasing VFA concentrations. The organic overloading induced a redistribution in the equitability of microorganisms and a loss of Archaea species. Community structure was not resilient changing rapidly after the OLR increased. Fast temporal replacement of functionally redundant microorganisms was observed.