Performance of a constructed wetland in Grand Marais, Manitoba, Canada: Removal of nutrients, pharmaceuticals, and antibiotic resistance genes from municipal wastewater

Abstract

BackgroundThe discharge of complex mixtures of nutrients, organic micropollutants, and antibiotic resistance genes from treated municipal wastewater into freshwater systems are global concerns for human health and aquatic organisms. Antibiotic resistance genes (ARGs) are genes that have the ability to impart resistance to antibiotics and reduce the efficacy of antibiotics in the systems in which they are found. In the rural community of Grand Marais, Manitoba, Canada, wastewater is treated passively in a sewage lagoon prior to passage through a treatment wetland and subsequent release into surface waters. Using this facility as a model system for the Canadian Prairies, the two aims of this study were to assess: (a) the presence of nutrients, micropollutants (i.e., pesticides, pharmaceuticals), and ARGs in lagoon outputs, and (b) their potential removal by the treatment wetland prior to release to surface waters in 2012.ResultsAs expected, concentrations of nitrogen and phosphorus species were greatest in the lagoon and declined with movement through the wetland treatment system. Pharmaceutical and agricultural chemicals were detected at concentrations in the ng/L range. Concentrations of these compounds spiked downstream of the lagoon following discharge and attenuation was observed as the effluent migrated through the wetland system. Hazard quotients calculated for micropollutants of interest indicated minimal toxicological risk to aquatic biota, and results suggest that the wetland attenuated atrazine and carbamazepine significantly. There was no significant targeted removal of ARGs in the wetland and our data suggest that the bacterial population in this system may have genes imparting antibiotic resistance.ConclusionsThe results of this study indicate that while the treatment wetland may effectively attenuate excess nutrients and remove some micropollutants and bacteria, it does not specifically target ARGs for removal. Additional studies would be beneficial to determine whether upgrades to extend retention time or alter plant community structure within the wetland would optimize removal of micropollutants and ARGs to fully characterize the utility of these systems on the Canadian Prairies.

Pharmaceuticals and pesticides archived on polar passive sampling devices can be stable for up to 6 years

“…The o-DGT deployed in the wastewater treatment facility show analyte storage after exposure to a real environmental matrix and represent actual use of many passive sampling devices [9,10]. The storage data in this case were limited to the occurrence and detection of analytes at the specific sampling site, namely, atrazine, carbamazepine, gemfibrozil, naproxen, sulfamethoxazole, sulfapyridine, and trimethoprim (Table 3).…”

“…The authors observed stable storage with POCIS in the freezer (-20 8C) for a suite of target analytes over approximately 1.5 yr [7]. The utility of this work is evident in studies requiring storage of POCIS before analysis [9,10]. There have been studies on the stability of pharmaceutical and pesticide residues in surface waters stored refrigerated [11] and frozen in raw wastewater samples [12] and in preserved or pretreated (e.g., addition of ethylenediaminetetraacetic acid) water samples [13].…”

Environmental impact and biological removal processes of pharmaceutically active compounds: The particular case of sulfonamides, anticonvulsants and steroid estrogens

“…Moreover, similar results showing slight or no removal were obtained for CBZ and 5 of its metabolites (10,11-dihydro-10,11-dihydroxy-CBZ, 10,11-dihydro-10-hydroxy-CBZ, 10,11-epoxy-10,11-dihydro-CBZ, 2-hydroxy-CBZ and 3-hydroxy-CBZ) in German and Portuguese full-scale WWTPs (Bahlmann et al, 2014). On the other hand, full-scale constructed wetlands (CW) were useful for CBZ and SMX removal purposes (Gross, Montgomery-Brown, Naumann, & Reinhard, 2004;Matamoros, Garc ıa, & Bayona, 2008;Hijosa-Valsero, Matamoros, Mart ın-Villacorta, B ecares, & Bayona, 2010;Anderson et al, 2013;Lee, Lee, Park, Kim, & Cho, 2013). Nevertheless, conflicting results have been reported by these authors, ranging from no effective removal of both compounds in a study conducted in Canada (Anderson et al, 2013), from 15 to 37% CBZ removal efficiencies in full-scale and surface flow CW reported in Spain (Hijosa-Valsero et al, 2010).…”

Fate of Environmental Pollutants

“…Environment Research, Volume 86, Number 10-Copyright © 2014 Water Environment FederationUsing a treatment facility composed of a lagoon followed by wetland as a model system the presence and ARGs in lagoon outputs, and their potential removal by the treatment wetland prior to release to surface waters in 2012 were investigated. The results of this study indicated that while the treatment wetland may effectively attenuate excess nutrients and remove some micropollutants and bacteria, it does not does not achieve efficient ARGs removal(Anderson et al, 2013).Burch et al (2013) investigated whether airdrying beds reduce antibiotic resistance gene (ARC) concentrations in residual municipal wastewater solids. Three laboratory-scale drying beds were operated for a period of nearly 100 days.…”