Enzymatic and microbial transformation assays for the evaluation of the environmental fate of diclofenac and its metabolites

Lee, Hyun Jeoung; Lee, Eun-Hwa; Yoon, Sung Hwa; Chang, Hee Ra; Kim, Kyun; Kwon, Jung Hwan

doi:10.1016/j.chemosphere.2012.02.018

Cited by 37 publications

(15 citation statements)

References 45 publications

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“…Hydroxy DCF isomers were also detected as TPs under ozonation [53], photo-Fenton [44] as well as under photocatalytic conditions [16,22,60]. In addition, 4 -OH-DCF was identified as the main bio-TP during the microbial degradation test of DCF [64].…”

Section: Transformation Of Dcfmentioning

confidence: 91%

Proposed transformation pathway and evolution profile of diclofenac and ibuprofen transformation products during (sono)photocatalysis

Michael¹,

Achilleos²,

Lambropoulou³

et al. 2014

Applied Catalysis B: Environmental

128

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Liquid chromatography time-of-flight mass spectrometry (UPLC/ESI-QToF-MS) was used for the elucidation of the main transformation products (TPs) resulting from the degradation of diclofenac (DCF) and ibuprofen (IBP) during the application of various advanced oxidation processes in aqueous matrices. The examined processes were TiO 2 photocatalysis driven by UV-A or simulated solar irradiation, sonolysis, and UV-A photocatalysis integrated with ultrasound irradiation (sonophotocatalysis). A comparison between the applied treatment processes was performed with respect to the substrates first-order kinetic rate constant. When compared with sonolysis and UV-A photocatalysis, a higher degradation rate was observed for sonophotocatalysis in the presence of 500 mg L −1 TiO 2 . Seven TPs of IBP and ten TPs of DCF under UV-A and simulated solar irradiation photocatalysis and sonophotocatalysis, formed by consecutive attack of hydroxyl radicals (HO • ) in concomitance with the degradation of the primary compounds, were tentatively identified. Overall, no differences were observed in the nature of TPs formed for each substrate among the experiments performed, indicating the involvement of similar reaction mechanisms. The degradation pathway of IBP includes mainly decarboxylation, demethylation and hydroxylation reactions, while the oxidation of DCF, mainly proceeded by oxidation and hydroxylation reactions between chloroaniline and phenylacetic acid. An important observation made during the experiments was that the hydroxylated species (1 -OH-IBP; 2 -OH-IBP; 4 -OH-DCF; 5 -OH-DCF) remained in the solution until 120 min. Finally, the results demonstrated the capacity of the sonophotocatalysis to reduce the initial toxicity of IBP and DCF aqueous solutions against the water flea Daphnia magna yielding 20% and 40% immobilization, respectively, at the end of the treatment.

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Section: Transformation Of Dcfmentioning

confidence: 91%

Proposed transformation pathway and evolution profile of diclofenac and ibuprofen transformation products during (sono)photocatalysis

Michael¹,

Achilleos²,

Lambropoulou³

et al. 2014

Applied Catalysis B: Environmental

128

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“…ACCEPTED MANUSCRIPT 20 and k bio . DCF is also excreted as sulfate and glucuronide conjugates (Stierlin and Faigle, 1979), and its formation was reported in laboratory experiments (Lee et al, 2012) and in fullscale WWTPs (Zhang et al, 2008;Plósz et al, 2012;Vieno and Sillanpää, 2014). As to MET, excretion as conjugated metabolite is negligible (Escher et al, 2006).…”

Section: A C C E P T E Dmentioning

confidence: 95%

Removal of pharmaceuticals in pre-denitrifying MBBR – Influence of organic substrate availability in single- and three-stage configurations

et al. 2017

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Due to the limited efficiency of conventional biological treatment, innovative solutions are being explored to improve the removal of trace organic chemicals in wastewater. Controlling biomass exposure to growth substrate represents an appealing option for process optimization, as substrate availability likely impacts microbial activity, hence organic trace chemical removal. This study investigated the elimination of pharmaceuticals in pre-denitrifying moving bed biofilm reactors (MBBRs), where biofilm exposure to different organic substrate loading and composition was controlled by reactor staging. A three-stage MBBR and a single-stage reference MBBR (with the same operating volume and filling ratio) were operated under continuous-flow conditions (18 months). Two sets of batch experiments (day 100 and 471) were performed to quantify and compare pharmaceutical removal and denitrification kinetics in the different MBBRs. Experimental results revealed the possible influence of retransformation (e.g., from conjugated metabolites) and enantioselectivity on the removal of selected pharmaceuticals. In the second set of experiments, specific trends in denitrification and biotransformation kinetics were observed, with highest and lowest rates/rate constants in the first (S1) and the last (S3) staged sub-reactors, respectively. These observations were confirmed by removal efficiency data obtained during continuous-flow operation, with limited removal (<10%) of recalcitrant pharmaceuticals and highest removal in S1 within the three-stage MBBR. Notably, biotransformation rate constants obtained for non-recalcitrant pharmaceuticals correlated with mean specific denitrification rates, maximum specific growth rates and observed growth yield values. Overall, these findings suggest that: (i) the long-term exposure to tiered substrate accessibility in the three-stage configuration shaped the denitrification and biotransformation capacity of biofilms, with significant reduction under substrate limitation; (ii) biotransformation of pharmaceuticals may have occurred as a result of cometabolism by heterotrophic denitrifying bacteria.

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“…The transformation pathways in biological wastewater treatment reported thus far stop mostly at the level of primary TPs (direct TPs of DCF) and do not include secondary or tertiary TPs, although the biodegradability of some primary TPs is already known (Lee et al., 2012). The slow and incomplete transformation of DCF poses a challenge to identify TPs, since long incubation periods are needed and the TP concentrations are rather low.…”

Section: Introductionmentioning

confidence: 99%

Transformation of diclofenac in hybrid biofilm–activated sludge processes

et al. 2016

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The biotransformation of diclofenac during wastewater treatment was investigated. Attached growth biomass from a carrier-filled compartment of a hybrid-MBBR at the wastewater treatment plant (WWTP) in Bad Ragaz, Switzerland was used to test the biotransformation. Laboratory-scale incubation experiments were performed with diclofenac and carriers and high-resolution LC–QTof-MS was implemented to monitor the biotransformation. Up to 20 diclofenac transformation products (TPs) were detected. Tentative structures were proposed for 16 of the TPs after characterization by MS2 fragmentation and/or inferring the structure from the transformation pathway and the molecular formula given by the high resolution ionic mass. The remaining four TPs were unambiguously identified via analytical reference standards. The postulated reactions forming the TPs were: hydroxylation, decarboxylation, oxidation, amide formation, ring-opening and reductive dechlorination. Incubation experiments of individual TPs, those which were available as reference standards, provided a deeper look into the transformation pathways. It was found that the transformation consists of four main pathways but no pathway accounted for a clear majority of the transformation. A 10-day monitoring campaign of the full-scale plant confirmed an 88% removal of diclofenac (from approximately 1.6 μg/L in WWTP influent) and the formation of TPs as found in the laboratory was observed. One of the TPs, N-(2,6-dichlorophenyl)-2-indolinone detected at concentrations of around 0.25 μg/L in WWTP effluent, accounting for 16% of the influent diclofenac concentration. The biotransformation of carriers was compared to a second WWTP not utilising carriers. It was found that in contact with activated sludge, similar hydroxylation and decarboxylation reactions occurred but at much slower rates, whereas some reactions, e.g. reductive dechlorination, were not detected at all. Finally, incubation experiments were performed with attached growth biomass from a third WWTP with a similar process configuration to Bad Ragaz WWTP. A similarly effective removal of diclofenac was found with a similar presence of TPs.

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Enzymatic and microbial transformation assays for the evaluation of the environmental fate of diclofenac and its metabolites

Cited by 37 publications

References 45 publications

Proposed transformation pathway and evolution profile of diclofenac and ibuprofen transformation products during (sono)photocatalysis

Proposed transformation pathway and evolution profile of diclofenac and ibuprofen transformation products during (sono)photocatalysis

Removal of pharmaceuticals in pre-denitrifying MBBR – Influence of organic substrate availability in single- and three-stage configurations

Transformation of diclofenac in hybrid biofilm–activated sludge processes

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