Impacts and fate of triclosan and sulfamethoxazole in intensified re-circulating vertical flow constructed wetlands

Mark Button; Katryn Cosway; Jessie Sui; Kela Weber

doi:10.1016/j.scitotenv.2018.08.395

Impacts and fate of triclosan and sulfamethoxazole in intensified re-circulating vertical flow constructed wetlands

Sci Total Environ. 2019 Feb 1:649:1017-1028. doi: 10.1016/j.scitotenv.2018.08.395. Epub 2018 Aug 28.

Authors

Mark Button¹, Katryn Cosway², Jessie Sui³, Kela Weber⁴

Affiliations

¹ Fipke Laboratory for Trace Element Research, University of British Columbia Okanagan, University Way, Kelowna, British Columbia V1V 1V7, Canada.
² Environmental Sciences Group, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, PO Box 17000, Station Forces, K7K 7B4, Canada.
³ Caprion Biosciences Inc., 201 avenue Président-Kennedy, suite 3900, Montréal, Québec H2X 3Y7, Canada.
⁴ Environmental Sciences Group, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, PO Box 17000, Station Forces, K7K 7B4, Canada. Electronic address: kela.weber@rmc.ca.

PMID: 30179808
DOI: 10.1016/j.scitotenv.2018.08.395

Abstract

The impacts to microbial function, overall performance and eventual fate were assessed for triclosan (TCL) and sulfamethoxazole (SMX) in intensified (re-circulating) vertical subsurface flow (VSSF) constructed wetlands (CWs). The potential toxicity of each pharmaceutical to the intrinsic microbial communities was first assessed over a wide exposure range (0-1000 μg/l) via an ex-situ dose-response assay to estimate the concentration at which adverse effects were likely to occur. Based on these results an acute (7 day) in-situ exposures (500 μg/l) were then performed and impacts to the mesocosm systems monitored for 1 month via community-level physiological profiling (CLPP) alongside chemical oxygen demand (COD) removal rates and a range of water quality, and hydrological parameters. Despite the clear potential for negative impacts to microbial function from both compounds observed at 100 μg/l in the ex-situ dose-response test, no impacts were observed for the 500 μg/l in-situ exposure in the VSSF mesocosms. COD removal, water chemistry, plant health, and hydrological parameters did not significantly change in response to the in-situ exposure. In terms of fate, the removal efficiency for both TCL and SMX was high (>80%) after 1 h and complete removal (>99.7%) was observed after 168 h. Following the in-situ exposure, and subsequent one month effects-monitoring period, the mesocosms were decommissioned with the media biofilm spatially assessed for organic content as well as TCL and SMX concentrations. TCL and SMX were found to have persisted in the media and demonstrated spatial variation with an overall 2-20% and 5-6% recovered respectively. This suggests that biofilm bound TCL and SMX were biologically degraded in VSSF CWs, however may also accumulate in the biofilm if TCL and SMX are maintained in the influent. These results reinforce the robustness and potential of constructed wetlands for the treatment of pharmaceutical and personal care product (PPCP) contaminated wastewater.

Keywords: Constructed wetland; Ecotoxicity; Microbial community; PPCPs; Sulfamethoxazole; Triclosan.