Relative contribution of ammonia oxidizing bacteria and other members of nitrifying activated sludge communities to micropollutant biotransformation

WATER RESEARCH

卷:109

Article

Men, Yujie^1,2  Achermann, Stefan^1,4  Helbling, Damian E.³  Johnson, David R.¹  Fenner, Kathrin^1,4 

[1] Swiss Fed Inst Aquat Sci & Technol, Eawag, CH-8600 Dubendorf, Switzerland

[2] Univ Illinois, Dept Civil & Environm Engn, Urbana, IL 61801 USA

[3] Cornell Univ, Sch Civil & Environm Engn, Ithaca, NY 14853 USA

[4] Swiss Fed Inst Technol, Inst Biogeochem & Pollutant Dynam, CH-8092 Zurich, Switzerland

关键词: Micropollutant;    Allylthiourea;    Octyne;    Ammonia-oxidizing bacteria;    Wastewater treatment plants;    Biotransformation;   

DOI  :  10.1016/j.watres.2016.11.048

来源: Elsevier

【 摘 要 】

Improved micropollutant (MP) biotransformation during biological wastewater treatment has been associated with high ammonia oxidation activities, suggesting co-metabolic biotransformation by ammonia oxidizing bacteria as an underlying mechanism. The goal of this study was to clarify the contribution of ammonia oxidizing bacteria to increased MP degradation in nitrifying activated sludge (NAS) communities using a series of inhibition experiments. To this end, we treated a NAS community with two different ammonia oxidation inhibitors, namely octyne (OCT), a mechanistic inhibitor that covalently binds to ammonia monooxygenases, and allylthiourea (ATU), a copper chelator that depletes copper ions from the active center of ammonia monooxygenases. We investigated the biotransformation of 79 structurally different MPs by the inhibitor-treated and untreated sludge communities. Fifty-five compounds exhibited over 20% removal in the untreated control after a 46 h-incubation. Of these, 31 compounds were significantly inhibited by either ATU and/or OCT. For 17 of the 31 MPs, the inhibition by ATU at 46 h was substantially higher than by OCT despite the full inhibition of ammonia oxidation by both inhibitors. This was particularly the case for almost all thioether and phenylurea compounds tested, suggesting that in nitrifying activated sludge communities, ATU does not exclusively act as an inhibitor of bacterial ammonia oxidation. Rather, ATU also inhibited enzymes contributing to MP biotransformation but not to bulk ammonia oxidation. Thus, inhibition studies with ATU tend to overestimate the contribution of ammonia-oxidizing bacteria to MP biotransformation in nitrifying activated sludge communities. Biolog tests revealed only minor effects of ATU on the heterotrophic respiration of common organic substrates by the sludge community, suggesting that ATU did not affect enzymes that were essential in energy conservation and central metabolism of heterotrophs. By comparing ATU- and OCT-treated samples, as well as before and after ammonia oxidation was recovered in OCT-treated samples, we were able to demonstrate that ammonia-oxidizing bacteria were highly involved in the biotransformation of four compounds: asulam, clomazone, monuron and trimethoprim. (C) 2016 Elsevier Ltd. All rights reserved.

【 授权许可】

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