Investigating the ENvironmental impacts of TRANSformed engineered nanomaterials released from wastewater treatment plants

As the production, diversity and use of engineered nanomaterials (ENM) is, there are corresponding increases in ENM emissions to wastewater treatment plants (WWTP) from domestic and industrial sources. Due to their dynamic nature, ENM undergo significant physicochemical transformations during transport through WWTPs and further when emitted to the natural environment. This leads to altered ENM characteristics which can have a further impact on their fate, bioavailability and effects on organisms. ENTRANS addresses the research challenge of understanding the environmental impacts of transformed ENM released from WWTP on organisms from relevant environmental compartments (soils and sediments). ENTRANS provides (i) an improved understanding of the behaviour and transformation of ENM following release from WWTPs, (ii) environmental ENM levels that are currently missing, (iii) effects assessment of transformed ENM, (iv) integration of data for modelling fate, exposure and toxicity. Isotopically enriched ENM, encompassing 68ZnO, 46TiO2, and 109Ag were successfully synthesized using methods developed within the project. The use of such isotopically labelled ENM in experiments allows their fate to be traced at low, environmentally relevant exposure concentrations even in the presence of high backgrounds of similar natural particles. A pilot WWTP operating with real municipal wastewater was used to investigate the fate and transformation of the isotopically enriched ENM in the WWTP. The ENM were spiked into the WWTP and the digested sewage sludge and effluents of the WWTP were collected for uptake and toxicity assessment evaluation. The targeted ENM concentrations (in mg/kg /dry weight) in the sludge were achieved and as expected, significantly lower concentrations were measured in the effluent (e.g. ng/L for Ag). The effluents from the WWTP were used for aqueous exposure of benthic amphipods (Hyalella azteca) to investigate in detail the uptake, fate and biodistribution of the ENM in the invertebrates. First results show an impact of the WWTP process on the bioavailability of ENM in amphipods. Furthermore, the potential impact of salinity (freshwater vs. marine/brackish) on ENM availability is investigated. Ongoing and next steps include the uptake and long-term effects assessment of ENM on filter-feeding bivalves and long-term sublethal effects on epibenthic and sediment-dwelling organisms, as such organisms are considered most at risk to ENM exposure. Existing protocols for the respective biomarker assessment need to be adapted and optimized for the used species. The digested sludge will be used in experiments that focus on the fate and behavior of the ENM that were applied via the sludge in soil columns. This will allow assessments of the ENM bioavailability, uptake and long-term effects at low and environmentally relevant concentrations on terrestrial organisms. In an effort to simplify experiments with transformed ENM without inclusion of the laborious WWTP step, method development to generate artificially aged ENM is ongoing, to compare the fate and toxicological effects of pristine and transformed ENM. The project outcomes are expected to support the development of modelling and risk assessment tools for the sustainable development and use of nanotechnologies and ENM.

ENTRANS will study the transformation of engineered nanomaterials (ENMs) in wastewater treatment plants (WWTPs) and following their release in wastewater and sludge effluents, and how these transformations subsequently impact ENM bioavailability and toxicity to organisms from the soil and sediment environments considered the final sinks for ENMs. Isotopically labelled ENMs of ZnO, TiO2, Ag will be synthesized and used to differentiate ENM from natural particles at the low, environmentally relevant concentrations expected. The labelled ENM will allow transformation in a pilot WWTP system and biosolids that are applied to agricultural land to be studied more clearly, while their application as tracers will enable the potential uptake, biodistribution, depuration and impacts of ENM in different organisms to be studied more effectively. During the project the ENM occurrence and environmental levels will be determined in samples collected from WWTPs in Trondheim and Oslo and from sludge-amended soils. State of the art analytical and microscopy techniques will be employed to provide occurrence, form and exposure levels in WWTP biosolids applied in agricultural land in Norway, receiving soils and sediments. The transformation processes, exposure and uptake, biodistribution and toxicity data will be carefully generated so that the obtained results can be integrated into computational fate and exposure models and a risk assessment can be performed. During the project we will address key topics and bridge knowledge gap on sediment, soil health, nanomaterial transformation and environmental occurrence levels. The data generated during this study will be presented to stakeholders and interested parties and suggestions towards waste management will be provided. Moreover, the project will provide recommendations for OECD guideline developments and waste regulation supporting a more sustainable development and use of nanotechnology.

Publications from Cristin

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Nanotoxicology: status, challenges and needs - an environmental perspective

Investigations on the uptake and accumulation of wastewater-borne nanomaterials and released metals by the benthic amphipod Hyalella azteca under environmentally relevant conditions

Isotopically enriched nanoparticles to investigate the impact of wastewater treatment process on their bioavailability

ENTRANS: Investigating the ENvironmental impacts of TRANSformed engineered nanomaterials released from wastewater treatment plants

ENTRANS Investigating the ENvironmental impacts of TRANSformed engineered nanomaterials released from wastewater treatment plants

ENTRANS: Investigating the ENvironmental impacts of TRANSformed engineered nanomaterials released from wastewater treatment plants

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