Performance of an anaerobic–oxic–anoxic (AOA) system in the simultaneous removal of nutrients and triclosan and bacterial community

ABSTRACT

The constant presence of triclosan (TCS) in surface water and wastewater has been verified due to its application in several pharmaceutical and personal care products. Thus, removing this emerging contaminant is essential to minimize the contamination of water bodies. The anaerobic–aerobic-anoxic (AOA) system is an innovative alternative that combines the removal of nutrients and triclosan. This study focuses on the simultaneous removal of carbonaceous matter, nitrogen, phosphorus, and triclosan in a continuous pilot-scale AOA system from synthetic wastewater. The upflow system, in series, was operated at hydraulic retention time (HRT) of 8 h and a flowrate of 2.40 L h⁻¹. Glucose (190 mg L⁻¹) was added to the anoxic reactor as the external carbon source. Besides that, bacterial community structure was investigated using 16S rRNA sequencing in each reactor. The system achieved average removal efficiencies of 96% (14.03 g d⁻¹) for Chemical Oxygen Demand (COD), 85% (2.64 g d⁻¹) for Total Kjeldahl Nitrogen (TKN), 88% (1.40 g d⁻¹) for Total Ammonia Nitrogen (TAN), 20% (0.12 g d⁻¹) for Total Phosphorus (TP), and 93% (1.87 μg d⁻¹) for Triclosan (TCS). The phyla Proteobacteria, Firmicutes, Bacteroidetes, and Chloroflexi were found in greater abundance. The main genera identified were Anaeromusa, Aeromonas, Azospira, Clostridium, and Lactococcus. The organisms related to phylum and genus corroborate the involved processes and the removal performance achieved. In addition, Lactococcus, Thermomonas, Ferruginibacter, and Dechloromonas were involved in triclosan biodegradation. The anaerobic-oxic–anoxic system successfully removed carbonaceous, nitrogenous matter, and triclosan, with glucose increasing the denitrifying activity.

GRAPHICAL ABSTRACT

KEYWORDS:

• Anaerobic-oxic-anoxic (AOA)
• emergent contaminants
• nitrification
• denitrification
• 16s rRNA sequencing

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article and its supplementary materials.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This research was funded by Fundação Araucária, Companhia de Saneamento do Paraná [grant no 411/2014] and Coordination for the Improvement of Higher Education Personnel (Capes) [grant no Finance Code 001].