Reversibility of enzymatic reactions might limit biotransformation of organic micropollutants

González-Gil, Lorena; Carballa, Marta; Corvini, Philippe F.-X.; Lema, Juan M.

doi:10.1016/j.scitotenv.2019.02.143

Cited by 32 publications

(17 citation statements)

References 30 publications

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“…In such a case, we would always observe the same removal percentage at different concentrations and no removal increases with time or HRT. This was recently proposed by Gonzalez-Gil et al using a mechanistic model based on the reversibility of bisphenol phosphorylation by two key enzymes in anaerobic digestion: hexokinase and acetate kinase (Gonzalez-Gil et al, 2018;Gonzalez-Gil et al, 2019). Furthermore, He et al have reported higher carbamazepine concentrations in the effluent than in the influent of WWTPs due to reactions transforming conjugates back to carbamazepine (He et al, 2019).…”

Section: Pharmaceutical Removal At Different Hydraulic Retention Timesmentioning

confidence: 98%

“…However, recent experiments and models suggested that pharmaceutical and other OMP removal might not improve beyond a specific HRT (Gonzalez-Gil et al, 2018;Jiang et al, 2018;Boonnorat et al, 2019). Furthermore, Gonzalez-Gil et al hypothesized that this might be due to an equilibrium in the transformation or sorption processes (Gonzalez-Gil et al, 2018;Gonzalez-Gil et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, Gonzalez‐Gil et al. hypothesized that this might be due to an equilibrium in the transformation or sorption processes (Gonzalez‐Gil et al ., 2018; Gonzalez‐Gil et al ., 2019).…”

Section: Introductionmentioning

confidence: 99%

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Effect of concentration and hydraulic reaction time on the removal of pharmaceutical compounds in a membrane bioreactor inoculated with activated sludge

Rios‐Miguel

Jetten

Welte

2021

Microbial Biotechnology

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Pharmaceuticals are often not fully removed in wastewater treatment plants (WWTPs) and are thus being detected at trace levels in water bodies all over the world posing a risk to numerous organisms. These organic micropollutants (OMPs) reach WWTPs at concentrations sometimes too low to serve as growth substrate for microorganisms; thus, co-metabolism is thought to be the main conversion mechanism. In this study, the microbial removal of six pharmaceuticals was investigated in a membrane bioreactor at increasing concentrations (4-800 nM) of the compounds and using three different hydraulic retention times (HRT; 1, 3.5 and 5 days). The bioreactor was inoculated with activated sludge from a municipal WWTP and fed with ammonium, acetate and methanol as main growth substrates to mimic co-metabolism. Each pharmaceutical had a different average removal efficiency: acetaminophen (100%) > fluoxetine (50%) > metoprolol (25%) > diclofenac (20%) > metformin (15%) > carbamazepine (10%). Higher pharmaceutical influent concentrations proportionally increased the removal rate of each compound, but surprisingly not the removal percentage. Furthermore, only metformin removal improved to 80-100% when HRT or biomass concentration was increased. Microbial community changes were followed with 16S rRNA gene amplicon sequencing in response to the increment of pharmaceutical concentration: Nitrospirae and Planctomycetes 16S rRNA relative gene abundance decreased, whereas Acidobacteria and Bacteroidetes increased. Remarkably, the Dokdonella genus, previously implicated in acetaminophen metabolism, showed a 30-fold increase in abundance at the highest concentration of pharmaceuticals applied. Taken together, these results suggest that the incomplete removal of most pharmaceutical compounds in WWTPs is dependent on neither concentration nor reaction time. Accordingly, we propose a chemical equilibrium or a growth substrate limitation as the responsible mechanisms of the incomplete removal. Finally, Dokdonella could be the main acetaminophen degrader under activated sludge conditions, and non-antibiotic pharmaceuticals might still be toxic to relevant WWTP bacteria.

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Section: Pharmaceutical Removal At Different Hydraulic Retention Timesmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of concentration and hydraulic reaction time on the removal of pharmaceutical compounds in a membrane bioreactor inoculated with activated sludge

Rios‐Miguel

Jetten

Welte

2021

Microbial Biotechnology

View full text Add to dashboard Cite

show abstract

“…In such a case we would always observe the same removal percentage at different concentrations and no removal increase with time or HRT. This was recently proposed by Gonzalez-Gil et al using a mechanistic model based on the reversibility of bisphenol phosphorylation by two key enzymes in anaerobic digestion: hexokinase and acetate kinase (Gonzalez-Gil et al, 2019;Gonzalez-Gil et al, 2018). Furthermore, He et al…”

Section: Pharmaceutical Removal At Different Hydraulic Retention Timesmentioning

confidence: 99%

“…However, recent experiments and models suggested that pharmaceutical and other OMP removal might not improve beyond a specific 5 HRT (Boonnorat et al, 2019;Gonzalez-Gil et al, 2018;Jiang et al, 2018). Furthermore, Gonzalez-Gil et al hypothesized that this might be due to an equilibrium in the transformation or sorption processes (Gonzalez-Gil et al, 2019;Gonzalez-Gil et al, 2018) In order to get more insights about the (in)complete degradation of some pharmaceuticals in WWTPs, we have studied the effect of concentration and HRT on pharmaceutical removal in a membrane bioreactor. We also determined the changes in the microbial community in response to higher pharmaceutical concentrations and finally, we tested whether higher pharmaceutical concentrations resulted in higher relative abundance of specific MGEs previously correlated to pesticide occurrence and degradation.…”

Section: Introductionmentioning

confidence: 99%

Effect of concentration and hydraulic reaction time on the removal of pharmaceutical compounds in a membrane bioreactor inoculated with activated sludge

Rios‐Miguel

Jetten

Welte

2021

Preprint

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Pharmaceuticals are often not fully removed in wastewater treatment plants (WWTPs) and are thus being detected at trace levels in water bodies all over the world posing a risk to numerous organisms. These organic micropollutants (OMPs) reach WWTPs at concentrations sometimes too low to serve as growth substrate for microorganisms, thus co-metabolism is thought to be the main conversion mechanism. In this study, the microbial removal of six pharmaceuticals was investigated in a membrane bioreactor at increasing concentrations (4-800 nM) of the compounds and using three different hydraulic retention times (HRT; 1, 3.5, 5 days). The bioreactor was inoculated with activated sludge from a Dutch WWTP and fed with ammonium, acetate, and methanol as main growth substrates to stimulate and mimic co-metabolism in a WWTP. Each pharmaceutical compound had a different average removal efficiency: acetaminophen (100%) > fluoxetine (50%) > metoprolol (25%) > diclofenac (20%) > metformin (15%) > carbamazepine (10%). Higher pharmaceutical influent concentrations proportionally increased the removal rate of each compound, but surprisingly not the removal percentage. Furthermore, only metformin removal improved to 80-100% when HRT or biomass concentration was increased in the reactor. Microbial community changes were followed with 16S rRNA gene amplicon sequencing in response to the increment of supplied pharmaceutical concentration: it was found that Nitrospirae and Planctomycetes 16S rRNA relative gene abundance decreased, whereas Acidobacteria and Bacteroidetes increased. Remarkably, the Dokdonella genus, previously implicated in acetaminophen metabolism, showed a 30-fold increase in abundance at the highest (800 nM) concentration of pharmaceuticals applied. Taken together, these results suggest that the incomplete removal of most pharmaceutical compounds in WWTPs is neither dependent on concentration nor HRT. Accordingly, we propose a chemical equilibrium or a growth substrate limitation as the responsible mechanisms of the incomplete removal. Finally, Dokdonella could be the main acetaminophen degrader under activated sludge conditions, and non-antimicrobial pharmaceuticals might still be toxic to relevant WWTP bacteria.

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Fate of selected organic micropollutants during anaerobic sludge digestion

Hammer

Palmowski

2021

Water Environment Research

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Organic micropollutants are incompletely removed from wastewater in Water Resource Recovery Facilities using conventional methods and can therefore enter the anaerobic sludge treatment together with primary and secondary sludge. This review compiles literature data on the fate of selected micropollutants (Carbamazepine [CBZ], Diclofenac [DCF], Ibuprofen [IBP], Sulfamethoxazole [SMX], and Triclosan [TCS]) during anaerobic sludge treatment and how the fate is affected by chemical properties, phase distribution and operating conditions. CBZ was found to be persistent to anaerobic degradation in most studies, with some exceptions reporting a degradation efficiency of 60%. Removal efficiencies for DCF, IBP, and TCS varied widely (from no to [very] high removal). For SMX, most studies reported a removal above 80%. A correlation was found between the fate during anaerobic digestion and physicochemical properties (hydrophobicity and molecular structure). Sorption to sludge, affected in some cases by pH changes during digestion, is suggested to reduce bioavailability. IBP and TCS were mainly present in the liquid phase or solid phase, respectively, CBZ and DCF were present in similar proportions in both phases, while statements were contradictory for SMX. Parameters such as temperature and sludge age did not significantly influence the fate of investigated micropollutants during anaerobic digestion. Practitioner points Most studies report no significant removal of CBZ during anaerobic sludge digestion. Removal efficiencies of DCF, IBP, and TCS vary from study to study between no removal and high or very high removal. Considering such heterogeneous removal efficiencies, it is recommended to conduct digestion trials to find out in which range the values will be for a specific sludge. SMX is very highly removed during anaerobic digestion in most studies. Parameters such as temperature and SRT do not significantly influence the fate of the five investigated micropollutants. Hydrophobicity, which has some effect on the liquid/solid phase distribution of micropollutants, and molecular structure influence the removal efficiencies.

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Reversibility of enzymatic reactions might limit biotransformation of organic micropollutants

Cited by 32 publications

References 30 publications

Effect of concentration and hydraulic reaction time on the removal of pharmaceutical compounds in a membrane bioreactor inoculated with activated sludge

Effect of concentration and hydraulic reaction time on the removal of pharmaceutical compounds in a membrane bioreactor inoculated with activated sludge

Effect of concentration and hydraulic reaction time on the removal of pharmaceutical compounds in a membrane bioreactor inoculated with activated sludge

Fate of selected organic micropollutants during anaerobic sludge digestion

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