Abstract
In this study, a lab-scale wastewater treatment
plant (WWTP), simulating biological treatment, received 10
μg/L Ag and 100 μg/L TiO2 nanoparticles (NPs) for 5 weeks.
NP partitioning was evaluated by size fractionation (>0.7 μm,
0.1−0.7 μm, 3 kDa-0.1 μm, < 3 kDa) using inductively
coupled plasma mass spectrometry (ICP-MS), single particle
ICP-MS and transmission electron microscopy. The ecotoxicological
effects of the transformed NPs in the effluent were
assessed using a battery of marine and freshwater bioassays
(algae and crustaceans) and an in vitro gill cell line model
(RTgill-W1). TiO2 aggregates were detected in the effluent,
whereas Ag NPs (0.1−0.22 μg/L) were associated with S, Cu,
Zn. Fractionation showed that >80% of Ag and Ti were
associated with the effluent solids. Increased toxicity was
observed during weeks 2−3 and the effects were species-dependent; with marine epibenthic copepods and algae being the most
sensitive. Increased reactive oxygen species formation was observed in vitro followed by an increase in epithelial permeability.
The effluent affected the gill epithelium integrity in vitro and impacted defense pathways (upregulation of multixenobiotic
resistance genes). To our knowledge, this is the first study to combine a lab-scale activated sludge WWTP with extensive
characterization techniques and ecotoxicological assays to study the effects of transformed NPs in the effluent.
plant (WWTP), simulating biological treatment, received 10
μg/L Ag and 100 μg/L TiO2 nanoparticles (NPs) for 5 weeks.
NP partitioning was evaluated by size fractionation (>0.7 μm,
0.1−0.7 μm, 3 kDa-0.1 μm, < 3 kDa) using inductively
coupled plasma mass spectrometry (ICP-MS), single particle
ICP-MS and transmission electron microscopy. The ecotoxicological
effects of the transformed NPs in the effluent were
assessed using a battery of marine and freshwater bioassays
(algae and crustaceans) and an in vitro gill cell line model
(RTgill-W1). TiO2 aggregates were detected in the effluent,
whereas Ag NPs (0.1−0.22 μg/L) were associated with S, Cu,
Zn. Fractionation showed that >80% of Ag and Ti were
associated with the effluent solids. Increased toxicity was
observed during weeks 2−3 and the effects were species-dependent; with marine epibenthic copepods and algae being the most
sensitive. Increased reactive oxygen species formation was observed in vitro followed by an increase in epithelial permeability.
The effluent affected the gill epithelium integrity in vitro and impacted defense pathways (upregulation of multixenobiotic
resistance genes). To our knowledge, this is the first study to combine a lab-scale activated sludge WWTP with extensive
characterization techniques and ecotoxicological assays to study the effects of transformed NPs in the effluent.