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Biodegradation study of methadone by adapted activated sludge: Elimination kinetics, transformation products and ecotoxicological evaluation

Kostanjevečki, Petra; Sviličić Petrić, Ines; Lončar, Jovica; Smital, Tvrtko; Ahel, Marijan; Terzić, Senka (2019) Biodegradation study of methadone by adapted activated sludge: Elimination kinetics, transformation products and ecotoxicological evaluation. Chemosphere, 214 . pp. 719-728. ISSN 0045-6535

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The biotransformation study of difficult-to- degrade opioid analgesic methadone (MTHD) was performed by activated sludge culture adapted to high concentration of methadone (10 mg/L). The study included determination of elimination kinetics of the parent compound, taxonomic characterization of microbial culture, identification of biotransformation products (TPs) and assessment of ecotoxicological effects of biotransformation processes. The chemical analyses were performed by ultra- performance liquid chromatography/quadrupole- time-of-flight mass spectrometry, whereas the ecotoxicological assessment was made based on determinations of toxicity to freshwater algae. Changes of the adapted sludge culture during the experiment were followed using the 16S rRNA gene amplicon sequencing. Depending on the experimental conditions, the elimination efficiency of methadone (10 mg/L) varied from 9% to 93% with the corresponding half-lives from 11.4 days to 1.5 days. A significantly faster elimination (t1/2 from 1.5 days to 5.8 days) was achieved at cometabolic conditions, using glucose-containing media, as compared to the experiments with MTHD as a single organic carbon source (t1/2 = 11.4 days). Moreover, increased biotransformation rate following the additional supplementation of ammonia, revealed a possible importance of nitrogen availability for the transformation at cometabolic conditions. The elimination of parent compound was associated with the formation of 3 different TPs, two of which were identical to main human metabolites of MTHD, 2- Ethylidene- 1, 5-dimethyl-3, 3- diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl- 3, 3-diphenyl-1-pyrroline (EMDP). EDDP represented over 90% of the total TP concentration at the end of experiment. The biodegradation of MTHD was associated with a pronounced drop in algal toxicity, confirming a rather positive ecotoxicological outcome of the achieved biotransformation processes.

Item Type: Article
Additional Information: We are thankful to the staffs WWTPs for their cooperation in activated sludge collection. The technical assistance of Nenad Muhin is also highly appreciated. This research was financially supported by the Croatian Science Foundation (project COMPASS; grant number IP-2014-09-7031).
Uncontrolled Keywords: Methadone ; Biodegradation ; Biotransformation ; Transformation products ; EDDP ; Ecotoxicological evaluation
Subjects: NATURAL SCIENCES > Interdisciplinary Natural Sciences
Divisions: Division for Marine and Enviromental Research
Project titleProject leaderProject codeProject type
Sveobuhvatna procjena ponašanja i sudbine farmaceutski aktivnih tvari u okolišu: makrolidni antibiotici i opiodni analgetici-COMPASSSenka TerzićIP-2014-09-7031HRZZ
Depositing User: Tvrtko Smital
Date Deposited: 07 May 2020 08:43
DOI: 10.1016/j.chemosphere.2018.09.153

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