ABSTRACT
Phenol removal was investigated in anaerobic fixed-structured bed reactors, namely R1 and R2, treating synthetic wastewater simulating the soluble fraction of vinasse under strictly methanogenic (R1) and simultaneous methanogenic/sulfidogenic conditions (R2). Next-generation sequencing (Illumina MiSeq System) was used to further characterize the microbial communities in both systems. Phenol was completely and stably removed in R1 after a short operating period (≈55 days). Conversely, phenol removal in R2 required a longer period for biomass acclimation (≈125 days) to reach levels equivalent to R1. Volatile fatty acids (VFA) accumulation in R2, mainly due to the inhibition of the acetoclastic methanogenesis by sulfide, may have limited phenol removal in the initial operating phases, as intermediate steps from phenol degradation are thermodynamically dependent on the removal of acetate, hydrogen and bicarbonate. Overall, the potential for anaerobically removing phenol from complex wastewaters was confirmed, even at low phenol/COD ratios. 16S rRNA gene sequencing analysis showed a high correlation of taxonomic profile between R1 and the inoculum, whereas a lower correlation was observed between R2 and the inoculum samples. Functional inference further indicated that Syntrophus and Bacillus genera in R1 and Clostridium genus in both reactors possibly played a key-role in phenol degradation.
GRAPHICAL ABSTRACT
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Acknowledgement
The authors gratefully acknowledge the National Council for Scientific and Technological Development (CNPq) (grant number 131014/2012-9), the São Paulo Research Foundation (FAPESP) (grant number 2009/15984-0) and the Coordination for the Improvement of Higher Education Personnel (CAPES) for their financial support.
Disclosure statement
No potential conflict of interest was reported by the authors.
ORCID
Leandro Augusto Gouvêa de Godoi http://orcid.org/0000-0002-1514-3501
Lucas Tadeu Fuess http://orcid.org/0000-0001-8520-1124
Tiago Palladino Delforno http://orcid.org/0000-0002-1705-0763