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Effect of water and wastewater treatment on the properties of engineered nanomaterials (ENMs) in context of their fate, toxicity and interaction with other contaminants

Periodic Reporting for period 2 - SAFEnano (Effect of water and wastewater treatment on the properties of engineered nanomaterials (ENMs) in context of their fate, toxicity and interaction with other contaminants)

Reporting period: 2019-10-01 to 2020-09-30

Behavior of engineered nanomaterials (ENMs) in the environment differs from the pathways observed for larger particles. Due to the special properties of ENMs and a wide range of their applications, attempts are made to estimate the fate of ENMs in the environment and transformations during their use and storage . The release of ENMs may occur during the use of materials containing nanoparticles, their processing or disposal and storage. It is assumed that the major part of ENMs gets into the environment with wastewater. During their transport and release into the environment, ENMs may undergo different transformations. As released ENMs will firstly get into wastewaters, one can expect that they will be subject to various processes of transformation there. Transformations of the material (coated and nanohybrids) can therefore affect the core material, the capping agent, or both. We currently lack sufficient knowledge of the types, rates, and extent of transformations expected for ENMs during water and wastewater treatment.
The proposed study is the first which investigates how various water and wastewater treatment methods will influence the physicochemical and ecotoxicological properties of ENMs (Fig. 1). Recognition of this problem has an extremely important aspect of cognition in a situation of increasing ENMs production. Acquired new knowledge on this topic lead to a better understanding of the mechanisms and processes in the environment. The research will contribute to a broad base of knowledge that will be the basis for solving of known or expected future problems related to the use of ENMs. Innovative aspects of the work were:
(1) Investigation of the effects of different water and wastewater treatment process on ENMs properties (WP1);
(2) Determination of ENMs changes during water/wastewater treatment and how these changes affect ENMs fate (aggregation, mobility, bioaccumulation) in the environment (WP2);
(3) Determination of how change in ENMs properties may result in a change in the strength of interactions with other contaminants, thus affecting their bioavailability and toxicity (WP3);
(4) Evaluation of ENMs toxicity to different organisms in connection of changes ENMs properties (WP4).
The results showed that the treatments affected properties of ENMs and strictly related to kind of ENMs and kind of treatment. Generally, changes in ENMs properties did not affect their behaviour in environmental systems (aggregation rate). There were exceptions, but not visibly related to changed properties or method of treatment. Treatment of ENMs by H2O2, UV, chlorination and ozonation did not affect the release of elements (Zn, Cu) from nanocoated carbon nanoparticles and nanohybrids, thus the bioaccumulation of these elements by plants and insects was negligible. We observed that treatment may change the affinity of ENMs to emerging contaminants (increase or decrease depending on kind of treatment and ENMs), which may have serious environmental consequences. Ecotoxicological results differ depending on organisms tested and kind of ENMs. No effect of UV, H2O2 and UV/H2O2 treatment, as well as ozonation treatment of investigated ENMs, was observed.


1.2.1 Work Package 1
The results showed that the effect of treatment on physicochemical properties of ENMs depended on the method of treatment and material tested. No differences were observed in the properties of ENMs after their treatment between distilled water and modelled wastewater. However in the case of UV/H2O2 treatment as well as ozonation some changes were observed. For functionalized graphene nanoplatelets increasing of the surface area after UV/ H2O2 treatment of hydrocarbon functionalized GFs were observed. Generally, UV and H2O2 treatment of ENMs decreased the carbon content in these materials and increased the other elements, which was confirmed by FTIR spectra.

1.2.2 Work package 2
Size of aggregates with a few exceptions did not change depending on the treatment method and the type of particles. For most of the tested ENMs the treatment did not affect their behaviour in environmental systems and ENMs usually settle down regardless of the treatment after 3-5 days.
No difference in the concentration of Zn and Cu between the control (no nanoparticles) and experiments with pristine and treated ENMs were observed in particular elemental systems.

1.2.3 Work package 3
Phenanthrene (PHEN), triclosan (TCS), diclofenac (DFC), naproxen (NAP) and caffeine (CAF) were the model compounds To a large extent, the impact of individual treatments depended on the ENMs tested. The results varied and largely determined by the type of ENMs and the method of treatment.

1.2.4. Wok package 4
The risk assessment of ENMs before and after treatment in the context of their transformation was evaluated. The following tests were performed with Pseudokirchneriella subcapitata (algae), Lepidium sativum (plants), Vibrio fisheri (bacteria) as well as Folsomia candida (invertebrates).
The proposed project is expected to contribute significantly to the current scientific understanding of the fate and effects of ENMs on environment, which are currently poorly understood. Improving this understanding is recognised as one of the “grand challenges” that must be addressed by the European Research Area. The proposed collaboration with a world-leading institute outside Europe is the great benefit to the European community by both training the candidate to an internationally competitive level and transferring knowledge of state of the art scientific approaches to the European research community. Indeed, by allowing me to gain research experience in the highly collaborative settings of Duke, this fellowship therefore provided support for me to establish international connections with other researchers, which could form the basis of future independent collaborations. I believe that the proposed research will also result in publications in top quality scientific journals, as well as presentations at international meetings, which support the European standard for excellence in research. From point of view of socio-economic impact and the wider societal implications, the project provides many important aspects. Due to the increasing use of nanoparticles in various aspects of life (medicine, cosmetics, food), nanoparticles can pose a potential threat to living organisms, including humans. Up to date, research has mainly focused on the direct impact of nanoparticles, usually pristine (brand-new). In our research, we go further and focus on realistic conditions and changes that nanoparticles may undergo in the environment becasue these nanoparticles will have a direct impact on living organisms and the environment. Our studies have shown that as a result of water purification, the properties of nanoparticles can undergo changes that sometimes affect their environmental behavior and, above all, interaction with other dangerous contaminants presented in water. The extension of current knowledge in the field of presence and the impact of nanoparticles on the environment will contribute to better management of engineered nanoparticles. This will affect not only the quality of the environment but also quality of human health, which is directly connected with environment contamination. The reduction of the risk will affect the quality of life at all levels of life and will also ensure a secure for future generations.