Abstract
Chemical contamination of wastewater is a problem of great environmental concern, as it poses a hazard to both the ecosystem and to human health. In this study, we have performed a bioanalytical evaluation of the presence and removal efficiency for bioactive chemicals in wastewater treatment plants (WWTPs), using in vitro assays for toxicity endpoints of high relevance for human health. Water samples were collected at the inlet and outlet of five Swedish WWTPs, all adopting a treatment technology including pretreatment, primary treatment (sedimenation), seconday treatment (biological processes), post-sedimentation, and sludge handling. The water samples were analyzed for cytotoxicity, estrogenicity, androgenicity, aryl hydrocarbon receptor (AhR) activity, oxidative stress response (Nrf2) and the ability to activate NFĸB (nuclear factor kappa-light-chain-enhancer of activated B cells) signaling. We observed clear androgenic and estrogenic activities in all inlet samples. Androgenic and estrogenic activities were also observed in all outlet samples, but the activities were lower than the respective inlet sample. AhR activity was observed in all samples, with higher activities in the inlet samples compared to the outlet samples. The removal efficiency was found to be high for androgenic (>99% for two plants and 50–60% for two plants) and estrogenic (>90% for most plants) compounds, while the removal efficiency for AhR-inducing compounds was 50–60% for most plants and 16% for one plant.
Highlights
Wastewater contaminated with a wide range of chemicals can be an environmental problem of great concern for the aquatic system where the treated wastewater is discharged, especially if the chemicals are not targeted during the wastewater treatment process[1,2]
Wastewater samples were collected at the inlet and outlet of the wastewater treatment plants (WWTPs) and each sample was analyzed for cytotoxicity, estrogenicity, androgenicity, aryl hydrocarbon receptor activity, oxidative stress response (Nrf2) and the ability to activate NFĸB signaling
In the outlet water sample from WWTP5, Nrf[2] activity was observed with ECIR1.5 of relative enrichment factor (REF) 47, as compared to 8.1 for the inlet wastewater. These results indicate that the treatment processes in the studied WWTPs efficiently removes oxidative stress inducing compounds from the water, as shown by the increasing ECIR1.5 values between WWTP inlet and outlet samples for each plant
Summary
Wastewater contaminated with a wide range of chemicals can be an environmental problem of great concern for the aquatic system where the treated wastewater is discharged, especially if the chemicals are not targeted during the wastewater treatment process[1,2]. Wastewater samples were collected at the inlet and outlet of the WWTPs and each sample was analyzed for cytotoxicity, estrogenicity, androgenicity, aryl hydrocarbon receptor activity, oxidative stress response (Nrf2) and the ability to activate NFĸB (nuclear factor kappa-light-chain-enhancer of activated B cells) signaling With this approach, we were able to evaluate how efficiently the bioactive chemicals, both known and unknown, were removed from the water for a broad range of health-relevant toxicity endpoints
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