Bacterial Diversity Controls Transformation of Wastewater-Derived Organic Contaminants in River-Simulating Flumes

authored by
Malte Posselt, Jonas Mechelke, Cyrus Rutere, Claudia Coll, Anna Jaeger, Muhammad Raza, Karin Meinikmann, Stefan Krause, Anna Sobek, Jörg Lewandowski, Marcus A Horn, Juliane Hollender, Jonathan P Benskin

Hyporheic zones are the water-saturated flow-through subsurfaces of rivers which are characterized by the simultaneous occurrence of multiple physical, biological, and chemical processes. Two factors playing a role in the hyporheic attenuation of organic contaminants are sediment bedforms (a major driver of hyporheic exchange) and the composition of the sediment microbial community. How these factors act on the diverse range of organic contaminants encountered downstream from wastewater treatment plants is not well understood. To address this knowledge gap, we investigated dissipation half-lives (DT50s) of 31 substances (mainly pharmaceuticals) under different combinations of bacterial diversity and bedform-induced hyporheic flow using 20 recirculating flumes in a central composite face factorial design. By combining small-volume pore water sampling, targeted analysis, and suspect screening, along with quantitative real-time PCR and time-resolved amplicon Illumina MiSeq sequencing, we determined a comprehensive set of DT50s, associated bacterial communities, and microbial transformation products. The resulting DT50s of parent compounds ranged from 0.5 (fluoxetine) to 306 days (carbamazepine), with 20 substances responding significantly to bacterial diversity and four to both diversity and hyporheic flow. Bacterial taxa that were associated with biodegradation included Acidobacteria (groups 6, 17, and 22), Actinobacteria (Nocardioides and Illumatobacter), Bacteroidetes (Terrimonas and Flavobacterium) and diverse Proteobacteria (Pseudomonadaceae, Sphingomonadaceae, and Xanthomonadaceae). Notable were the formation of valsartan acid from irbesartan and valsartan, the persistence of N-desmethylvenlafaxine across all treatments, and the identification of biuret as a novel transformation product of metformin. Twelve additional target transformation products were identified, which were persistent in either pore or surface water of at least one treatment, indicating their environmental relevance.

Institute of Microbiology
External Organisation(s)
Stockholm University
Swiss Federal Institute of Aquatic Science and Technology (Eawag)
University of Bayreuth
Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB)
Technische Universität Darmstadt
University of Birmingham
Environmental Science & Technology
No. of pages
Publication date
Publication status
Peer reviewed
ASJC Scopus subject areas
Chemistry(all), Environmental Chemistry
Electronic version(s) (Access: Open) (Access: Open)