New project of the Membrane Technology group

The plastic industry contributes to the economic growth, having produced an output of 322 million tonnes (Mt) by 2015. Further, it is expected that their production output will double by 2035 and quadruple by 2050. This massive production has a great environmental impact and it is estimated that the ocean already contains over 150 Mt of plastics. Once in the environment, plastics undergo abiotic and biotic weathering processes that cause their degradation and fragmentation into smaller particles termed microplastics (MPs; defined as fragments <5 mm) and nanoplastics (NPs, defined as fragments < 1 µm).

MP and NP particles are emerging pollutants of increasing concern. They accumulate in the environment where their small size makes it easy for different aquatic species to ingest them, thus causing microplastics to enter the food chain. Further, MP can also contain other type of contaminants such as Persistant Organic Pollutants (POPs), heavy metals and other additives such as plastifyers, representing a persistent and ecotoxicological pollution problem with a potential impact on human health.

Big efforts on the research conducted in MPs have been conducted on seawater environment. However, recent studies revealed that the abundance of MPs in freshwaters is comparable to that of marine environment. Wastewater treatment plants (WWTPs) have been identified as one of the main dominant sources of MPs in freshwater. The MPs found in wastewaters consist for example of microbeads added in peeling lotions and toothpastes and synthetic fibers from textile and clothing. In general terms, all studies have indicated that primary and secondary wastewater treatments remove the majority of MPs. However, despite of the high removal ability of the wastewater treatment technologies, the research efforts have been limited to the quantification of relatively big size MPs, leaving small size microplastics and nanoplastics out of the studied size spectrum.

Lack of standardized methods for sampling, identification and quantification of small size micro-nanoplastics hinders a real evaluation of their release into the water bodies from the wastewater treatment plants.

The aim of nanoCLEAN project (Quantification, treatment and environmental impact of micro-nanoplastics in WWTPs) is to contribute evaluating and reducing micro-nanoplastic environmental impact in ecosystems of the urban wastewater treatment plants by filling the following identified research gaps:

• Gap 1: Widely used sampling methods limit the microplastic size to relatively big microplastics, neglecting the existence of smaller particles.
• Gap 2: Most of the current analytical methods used for microplastic identification and quantification are very labour-intensive procedures not capable of quantifying the entire size spectrum of micro-nanoplastics.
• Gap 3: Conventional wastewater treatment technologies are not designed to treat small size micro-nanoplastics. There is a profound lack of understanding of the removal capacity of micro-nanoplastics by advanced wastewater treatment technologies.
• Gap 4: Previous research on microplastic removal has not been focused on the evaluation of the environmental and economic implications of proposed exhaustive wastewater treatment technologies.
• Gap 5: Ecotoxicity of nanoplastics and its contribution in WWTPs effluents has not been quantified. Furthermore, hypothesis regarding the higher toxicity of smaller particles has not been studied in detail.

In nanoCLEAN project a systemic method is implemented, where the efficient removal of micro-nanoplastics using hybrid membrane systems (MBR-UF) is coupled with new sampling and sensitive quantification methods (Pyr-GC-MS). This is supported by Life Cycle Assessment and Life cycle Costing, where the environmental impact and cost evaluation of the implemented technologies will be conducted.

The nanoCLEAN project, funded by the Spanish State Research Agency, is led by Dr. Junkal Landaburu Aguirre, researcher at the IMDEA Water Institute belonging to the Membrane Technology group.