Diclofenac oxidation by biogenic manganese oxides.
Diclofenac, a nonsteroidal anti-inflammatory drug, is one of the most commonly detected pharmaceuticals in sewage treatment plant (STP) effluents. In this work, biologically produced manganese oxides (BioMnOx) were investigated to remove diclofenac. At neutral pH, the diclofenac oxidation with BioMnOx was 10-fold faster than with chemically produced MnO(2). The main advantage of BioMnOx over chemical MnO(2) is the ability of the bacteria to reoxidize the formed Mn(2+), which inhibits the oxidation of diclofenac. Diclofenac-2,5-iminoquinone was identified as a major transformation product, accounting for 5-10% of the transformed diclofenac. Except for 5-hydroxydiclofenac, which was identified as an intermediate, no other oxidation products were detected. Diclofenac oxidation was proportional to the amount of BioMnOx dosed, and the pseudo first order rate constant k was 6-fold higher when pH was decreased from 6.8 to 6.2. The Mn(2+) levels remained below the drinking water limit (0.05 mg L(-1)), thus indicating the efficient in situ microbiological regeneration of the oxidant. These results combined with previous studies suggest the potential of BioMnOx for STP effluent polishing.
Forrez
Ilse
I
Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Gent, Belgium.
Carballa
Marta
M
Verbeken
Kim
K
Vanhaecke
Lynn
L
Ternes
Thomas
T
Boon
Nico
N
Verstraete
Willy
W
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid / Q000379:methods; D004008:Diclofenac / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008345:Manganese / Q000737:chemistry; D017895:Manganese Compounds / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods; D008956:Models, Chemical; D010087:Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D016958:Pseudomonas putida / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis; D018508:Water Purification / Q000379:methods
D000894:Anti-Inflammatory Agents, Non-Steroidal; D017895:Manganese Compounds; D010087:Oxides; D014874:Water Pollutants, Chemical; D004008:Diclofenac; D008345:Manganese; C027424:manganese oxide; D010100:Oxygen; C016552:manganese dioxide