A circular economy in action: Give plastic wastes from the production of hollow-fibre membranes a second life

Image: Tails generated by the resizing of hollow fibre membrane bundle during manufacturing. © Manuela Melucci.

DOI.ORG/10.58214/LBMM1206

LIFE REMEMBRANCE has received funding from the LIFE Programme of the European Union. Entitled Give plastic wastes from the production of hollow-fibre membranes a second life. The project aims to face two main challenges impacting ecosystem conditions and human wellbeing: Drinking water pollution (by contaminants of emerging concern (ECs), including per- and polyfluoroalkyl substances (PFAS); and CO2 production (from Hollow Fibre Membrane (HFM) wastes disposal and incineration).

Profile: Letizia Bocchi

Letizia Bocchi has a PhD in Biochemistry, Biotechnology and Molecular Biology.

She is head of MEDICA laboratory, head of MEDICA patent office and general board member. She has been the co-ordinator of multiple research projects on the development of advanced and functionalised hollow fibre membranes.

She is also the co-ordinator of the EU-funded projects Graphil (Core 3 SH1 Graphene Flagship, Horizon 2020) and LIFE-REMEMBRANCE (LIFE programme 2020) and co-author of 14 publications on peer-reviewed international journals.

Profile: Manuela Melucci

Manuela Melucci, PhD, is senior researcher at the CNR – Institute for Organic Synthesis and Photoreactivity, (ISOF-CNR, Bologna, Italy) and Leader of the Advanced Materials Synthesis group of CNR-ISOF. Her research interests range from the design and synthesis of organic molecular materials for organic electronics to the synthesis of graphene composites for environmental and biomedical applications. She is currently deputy leader of the industrially lead initiative GRAPHIL (spearhead of the Graphene Flagship), co-ordinator of the EU project Flagera GO-FOR-WATER, and technical manager and principal investigator for CNR on the LIFE-REMEMBRANCE programme. She is also alternate representative delegate of CNR for the European Chemical Society (EuChems), a member of the Graphene Flagship standardisation committee and, in 2022, was member of the Body of Knowledge of the European Innovation Institute (EIT).

Generating scraps

The production of naïve plastic wastes from medical technology industry is a side-effect of disposable medical devices manufacturing. Many components in disposable medical devices are still made of plastic polymers and have no prospect of being replaced in the near future by either biodegradable or more environmental-friendly materials, due to some unique and advantageous characteristics such as transparency, resistance to sterilisation, biocompatibility, easy handling and processability, approval and registration across many health authorities worldwide.

The pathways towards the introduction of green and advanced materials are still to be pursued but it’s a long and costly journey. Hemofilters, dialysers, plasmafilters, hemoconcentrators are widely exploited biomedical devices allowing selective exchange of substances. The core of such devices consists of semipermeable membranes, specifically polymeric hollow fibre membranes with a very high density of pores per surface unit. The membrane is manufactured in bundles that need to be resized during device assembly, an operation that generates scraps of different sizes that constitute plastic production wastes that need to be disposed of.

Medica S.p.A. is a medtech company, located in the largest European biomedical district (Mirandola, Modena, Italy) and it’s the only Italian manufacturer of hollow fibre membranes in Medisulfone® polysulfone, (PSU) and polyethersulfone (PES). Based on its assembly and manufacturing process Medica generates tonnes of hollow fibre membrane scraps every year.

Image: Granules generated by scraps grinding of PSU-GO hollow fibre; scraps in batch or encapsulated into a lab scale prototype. © Manuela Melucci.

Drinking Water Directive

Co-operation between Medica and CNR-ISOF (Manuela Melucci, PhD, Bologna, Italy) started almost eight years ago on research topics related to water treatment and the removal of emerging contaminants.

Water is increasingly contaminated by chemicals deriving from drugs, cosmetics, and personal care products with suspect or certified effects on public health. Recently the European Union introduced a new Drinking Water Directive (DWD 2020/2184) including new emerging contaminants and/ or new thresholds, and the water safety plans approach for any water operators to foresee risks and adopt prompt solutions[1-2].

Adsorption on granular activated carbon (GAC) is the most exploited technology to remove trace contaminants from water in potabilisation plants. Besides the poor efficiency of GAC on several contaminants such as short-chain perpolyfluoroalkyl substances (PFAS) and other small polar molecules, or metal ions, its production, activation, transport, regeneration, and disposal have a huge environmental impact.

Finding alternative active materials and strategies to integrate with or replace existing ones is a major challenge. Several examples of new sorbents deriving from plastics have been reported in the last few years including wastes deriving from the production of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polystyrene (PS), and polyethylene terephthalate (PET), showing interesting adsorption properties toward a wide range of pollutants, including toxic hydrophobic, persistent, and bio-accumulative substances, such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichloroethanes (DDTs), heavy metals, and others[1-3].

In this framework, CNR recently demonstrated and patented (EP3208241)[7] the recycling of plastic wastes deriving from the MEDICA industrial production of Medisulfone® polysulfone hollow fibre (PSU-HF) membranes, aimed at obtaining porous microsized granules, with adsorption capability in water and air matrixes[6].

Image: Prototype with PSU granular scraps. © Manuela Melucci.

LIFE-REMEMBRANCE

Polysulfone hollow fibres are the most exploited membranes to realise ultrafiltration devices for biomedical filtration, gas separation, water disinfection, and more recently for nanomaterials purification. The working mechanism of these membranes relies on their porosity, which allows the retention of biomolecules and other species larger than the membrane cut-off. This research carried out at lab-scale inspired, and has led to, the LIFE-REMEMBRANCE project.

The aim of LIFE-REMEMBRANCE, funded by the European Union under the LIFE 2020 Programme (LIFE20 ENV/IT001001), is to give a second life to the PSU- and PES-derived scraps as granular adsorbent for water refinement. Medica’s primary role in the project is to recycle and convert plastic wastes in granular form and to provide them as a ready-to-use material in prototypes to CNR-ISOF for performance and removal tests at the small scale.

Image: SEM images of Medisulfone® hollow fibre membrane derived scraps: a) wall section of a single hollow fibre, b) broken edge of a hollow fibre, c) external surface and wall thickness with porosity, d) granules derived from hollow fibre waste. © Medica S.p.A.

Promising values

CNR-ISOF tested the removal capacity in normal tap water towards PFAS, heavy metals, Diclofenac (nonsteroidal anti-inflammatory drug), and Ofloxacine (antibiotic) among others. Promising removal capacity values for both organic and inorganic contaminants for the granules derived from PSU and graphene oxide (GO) enhanced PSU (PSU-GO), demonstrated that they can be converted into sorbent materials suitable for water treatment or refinement.

Adsorption experiments carried out on a mixture of 14 PFAS, demonstrated that PSU-GO outperforms both PSU and GAC. The same trend was observed also with Pb and Diclofenac, with PSU-GO showing the highest adsorption capacity. PSU-GO scraps originate from a special hollow fibre membrane production, that was optimised by Medica SpA over the last three years, thanks to another European Union-funded project (Graphil, Core 3 Graphene Flagship Spearhead) aimed at the development and enrichment of membranes with GO for the implementation of new adsorption functionalities.

Besides the promising preliminary tests of LIFE-REMEMBRANCE materials at the lab scale and the tap water matrix, the installation of pilots for field tests are foreseen during the project. One of the pilots will be installed at a potabilisation plant handled by the HERA Group (the Water Municipality of Emilia Romagna region, Italy), in order to verify if sorbents generated by hollow fibre membrane scraps can be used alone or in combination with existing technologies for water potabilisation. Medisulfone® is a registered trademark owned by Medica S.p.A.

Image: First scale-up of LIFE REMEMBRANCE cartridge. © Medica S.p.A.

Bibliography

[1] Chemical pollution has passed safe limit for humanity, say scientists; https://www.theguardian.com/environment/2022/jan/18/chemical-pollution-has-passedsafe-limit-for-humanity-say-scientists

[2] Persson, L.; Carney Almroth, B. M.; Collins, C. D.; Cornell, S.; de Wit, C. A.; Diamond, M. L.; Fantke, P.; Hassellöv, M.; MacLeod, M.; Ryberg, M. W.; Søgaard Jørgensen, P.; Villarrubia-Gómez, P.; Wang, Z.; Hauschild, M. Z., Outside the Safe Operating Space of the Planetary Boundary for Novel Entities. Environ. Sci. Technol. 2022, 56

[3], 1510-1521. [3] J.F. Provencher, S. Avery-Gomm, M. Liboiron, B.M. Braune, J.B. Macaulay, M.L. Mallory, R.J. Letcher, Are ingested plastics a vector of PCB contamination in northern fulmars from coastal Newfoundland and Labrador?, Environ. Res. 167 (2018) 184-190. https://doi.org/10.1016/j.envres.2018.07.025.

[4] M. Llorca, G. Schirinzi, M. Martínez, D. Barceló, M. Farré, Adsorption of perfluoroalkyl substances on microplastics under environmental conditions, Environ. Pollut. 235 (2018) 680-691. https://doi.org/10.1016/j.envpol.2017.12.075.

[5] X. Gao, I. Hassan, Y. Peng, S. Huo, L. Ling, Behaviors and influencing factors of the heavy metals adsorption onto microplastics: A review, Journal of Cleaner Production 319 (2021) 128777. https://doi.org/https://doi.org/10.1016/j.jclepro.2021.128777.

[6] M. Zambianchi, A. Aluigi, M.L. Capobianco, F. Corticelli, I. Elmi, S. Zampolli, F. Stante, L. Bocchi, F. Belosi, M.L. Navacchia, M. Melucci, Polysulfone Hollow Porous Granules Prepared from Wastes of Ultrafiltration Membranes as Sustainable A dsorbent for Water and Air Remediation, 1(7) (2017) 1700019. https://doi.org/https://doi.org/10.1002/adsu.201700019.

[7] POROUS GRANULES OF POLYSULPHONE OR DERIVATIVES THEREOF FOR THE REMOVAL OF ORGANIC MOLECULES FROM A FLUID, EP3208241 B1, 18/02/2016, M. Melucci, ML Navacchia, MEDICA S.p.A.