Transformation products of clindamycin in moving bed biofilm reactor (MBBR)

Gordon T H Ooi; Monica Escola Casas; Henrik R Andersen; Kai Bester

doi:10.1016/j.watres.2017.01.058

Transformation products of clindamycin in moving bed biofilm reactor (MBBR)

Water Res. 2017 Apr 15:113:139-148. doi: 10.1016/j.watres.2017.01.058. Epub 2017 Feb 2.

Authors

Gordon T H Ooi¹, Monica Escola Casas², Henrik R Andersen³, Kai Bester⁴

Affiliations

¹ Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet 115, 2800, Kgs. Lyngby, Denmark; Institute of Environmental Science, Aarhus University, Frederiksborgsvej 399, 4000, Roskilde, Denmark.
² Institute of Environmental Science, Aarhus University, Frederiksborgsvej 399, 4000, Roskilde, Denmark.
³ Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet 115, 2800, Kgs. Lyngby, Denmark.
⁴ Institute of Environmental Science, Aarhus University, Frederiksborgsvej 399, 4000, Roskilde, Denmark. Electronic address: kb@envs.au.dk.

PMID: 28213335
DOI: 10.1016/j.watres.2017.01.058

Abstract

Clindamycin is widely prescribed for its ability to treat a number of common bacterial infections. Thus, clindamycin enters wastewater via human excretion or disposal of unused medication and widespread detection of pharmaceuticals in rivers proves the insufficiency of conventional wastewater treatment plants in removing clindamycin. Recently, it has been discovered that attached biofilm reactors, e.g., moving bed biofilm reactors (MBBRs) obtain a higher removal of pharmaceuticals than conventional sludge wastewater treatment plants. Therefore, this study investigated the capability of MBBRs applied in the effluent of conventional wastewater treatment plants to remove clindamycin. First, a batch experiment was executed with a high initial concentration of clindamycin to identify the transformation products. It was shown that clindamycin can be removed from wastewater by MBBR and the treatment process converts clindamycin into the, possibly persistent, products clindamycin sulfoxide and N-desmethyl clindamycin as well as 3 other mono-oxygenated products. Subsequently, the removal kinetics of clindamycin and the formation of the two identified products were investigated in batch experiments using MBBR carriers from polishing and nitrifying reactors. Additionally, the presence of these two metabolites in biofilm-free wastewater effluent was studied. The nitrifying biofilm reactor had a higher biological activity with k-value of 0.1813 h^-1 than the reactor with polishing biofilm (k = 0.0161 h^-1) which again has a much higher biological activity for removal of clindamycin than of the suspended bacteria (biofilm-free control). Clindamycin sulfoxide was the main transformation product which was found in concentrations exceeding 10% of the initial clindamycin concentration after 1 day of MBBR treatment. Thus, MBBRs should not necessarily be considered as reactors mineralizing clindamycin as they perform transformation reactions at least to some extent.

Keywords: Antibiotics; Biofilm; Degradation; Metabolites; Waste water.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biofilms*
Bioreactors / microbiology*
Clindamycin
Sewage / microbiology
Waste Disposal, Fluid
Wastewater

Substances

Sewage
Waste Water
Clindamycin