Studies on the bioaugmentation of Mycolicibacterium aubagnense HPB1.1 in aerobic granular sludge from a WWTP: Adaptability of native prokaryotes and enhancement of paracetamol intermediate metabolites biodegradation

Abstract

This study aimed to evaluate for the first time the bioaugmentation of Mycolicibacterium aubagnense HPB1.1 in Sequencing Batch Reactors (SBRs) with Aerobic Granular Sludge (AGS), and its effect on the biodegradation of Paracetamol, also known as Acetaminophen and N -acetyl-para-aminophenol (APAP). The bioaugmentation was effective and persisted for at least nine days after five inoculations performed in 24 days (relative abundance of M. aubagnense was 0.13 ± 0.05 % in the test reactors and 0.0079 ± 0.0008 % in the control reactors) and for eight days after seven inoculations performed in 40 days (relative abundance of M. aubagnense was 0.04 ± 0.02 % in the tests and 0.0005 ± 0.0005 % in the controls). In what concerns APAP biodegradation, the results showed a faster removal of its transformation products Hydroquinone (HQ), 2,5-dihydroxy-1,4-benzoquinone (2,5-HO-BQ) and 1,4-benzoquinone (BQ) in the bioreactors bioaugmented with the bacterial strain M. aubagnense HPB1.1 (59 % or 85 % of HQ, 67 % or 85 % of 2,5-HO-BQ and 75 % or 82 % of BQ removals, respectively for assay 1 or assay 2) in comparison to the non-bioaugmented bioreactors (15 % or 31 % of HQ, 36 % or 63 % of 2,5-HO-BQ and no removal of BQ, also for assy 1 and 2, respectively). Regarding the effect on organics and nutrients treatment, overall, the SBR conditions favored ammonia, nitrites, and organics removal. Yet, the conditions did not allow complete denitrification nor higher assimilation than release of PO₄^3-.