Compared microbiology of granular sludge under autotrophic, mixotrophic and heterotrophic denitrification conditions

摘要

Water contamination by nitrate is a wideworld extended phenomena. Biological autotrophicndenitrification has a real potential to face this problem and presents less drawbacks than thenmost extended heterotrophic denitrification. Three bench-scale UASB reactors were operatednunder autotrophic (R1, H2S as electron donor), mixotrophic (R2, H2S plus p-cresol as electronndonors) and heterotrophic (R3, p-cresol as electron donor) conditions using nitrate as terminalnelectron acceptor. 16S rDNA genetic libraries were built up to compare their microbialnbiodiversity. Six different bacteria phyla and three archaeal classes were observed.nProteobacteria was the main phyla in all reactors standing out the presence of denitrifiers.nMicroorganisms similar to Thiobacillus denitrificans and Acidovorax sp. performed the autotrophicndenitification. These OTUs were displaced by chemoheterotrophic denitrifiers, especially bynLimnobacter-like and Ottowia-like OTUs. Other phyla were Bacteroidetes, Chloroflexi, Firmicutesnand Actinobacteria that - as well as Archaea members - were implicated in the degradation ofnorganic matter, as substrate added as coming from endogenous sludge decay under autotrophicnconditions. Archaea diversity remained low in all the reactors being Methanosaeta concilii thenmost abundant one.