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Assessing the cumulative pressure of micropollutants in Swedish wastewater effluents and recipient water systems using integrated toxicological and chemical methods

Golovko, Oksana; Lundqvist, Johan; Örn, Stefan; Ahrens, Lutz


In recent decades, a substantial amount of work has been conducted to determine the occurrence, fate, and effects of organic micropollutants (OMPs) in aquatic environments. Incomplete removal of OMPs by conventional wastewater treatment plants (WWTPs) has been observed, and OMPs have been detected in surface water worldwide. In this study, WWTP influent, effluent, and sludge, and upstream and downstream waters in WWTP recipients, were analyzed for a total of 225 OMPs, including pharmaceuticals, hormones, personal care products, industrial chemicals, PFASs, and pesticides. The OMPs were selected based on annual usage in a wide range of household products and concerns about possible effects on humans and aquatic organisms. In addition, 11 different types of toxicity bioassays and fish embryo toxicity tests were applied to WWTP influent and effluent, and upstream and downstream waters in WWTP recipients.

A total of 158 contaminants were detected in at least one sample, in mean concentrations ranging from ng/L to mg/L in wastewater samples and from ng/L to μg/L in surface water samples. Two industrial chemicals (tetraethyleneglycol, laureth-5 and di-(2-ethylhexyl)phosphoric acid), 15 pharmaceuticals (salicylic acid, diclofenac, losartan, valsartan, venlafaxine, oxazepam, lamotrigine, carbamazepine, tramadol, hydrochlorothiazide, theophyline, furosemide, ranitidine, bicalutamide, and metformin), and the stimulants caffeine and nicotine were responsible for 70% of the combined concentration of pollutants in WWTP influent and effluent, and in surface water. Of the 225 target OMPs, 104 were detected in sludge samples. Analysis of sludge revealed large variations in concentrations between individual WWTPs, which can be explained by differences in OMP composition in influent water and in operating conditions at WWTPs.

In vitro toxicity testing showed relatively high activities for the studied endpoints in influent waters. The removal efficiency in WWTPs varied between endpoint and plant. For estrogenic and androgenic activities, the removal efficiency was consistently high (97-99%). For AhR activity and oxidative stress, the removal efficiency ranged from 60 to 99% in different WWTPs.

The results revealed that the high concentrations of OMPs in WWTPs and sludge are introduced to aquatic environments. However, there is limited information about the removal mechanisms of OMPs in WWTPs. Advanced technologies, namely membrane filtration, carbon adsorption, and AOPs (advanced oxidative processes), are now being widely adopted for OMPs removal, but the performance and cost of different unit processes vary by case. Therefore, the influence of treatment performance and process stability in WWTPs on reducing the effects and concentrations of OMPs should be evaluated. The results could provide a theoretical basis for optimization of existing treatment systems of different designs, and could contribute significantly to protecting recipient waters.

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Utgivare: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences