SETUP OF THE FILTERING SYSTEMS, ANALYSIS OF THE COLLECTED MICROFIBERS AND ECODESIGN OF THE FILTER

The development and validation of an innovative filter with dimensions between 80 and 5 μm, including a control system designed to evaluate the degree of filter saturation, is the first objective of the project: an intelligent filter equipped with a sensor capable of evaluating the amount of fibres retained and therefore signalling their saturation. The sensor is based on printed electrodes (screen printed electrode – SPE), applied in strategic positions, capable of determining the quantity of retained microplastic, and giving an estimate of its degree of saturation and when it needs to be changed/cleaned. This estimate is carried out by the electrodes through impedance measurements, i.e. the change in charge transfer at the electrode interface, when a small Alternating Current signal is applied to the interface with a constant DC offset (Impedance Spectroscopy - EIS). The frequency of the most appropriate alternating voltage will be identified which, once applied, is capable of quantifying the adhered microplastic in a proportional manner to the increase in charge transfer resistance on the surface of the SPE electrodes. Furthermore, this type of measurement is carried out in a differential manner (difference between a zero point - no microplastic - and the point at which the microplastic interacts) and will also allow to define the maximum load of the filter and its saturation (i.e. when it must be changed) . The microfibers collected by the filter will be characterized from a morphological (size distribution) and compositional point by using spectroscopic techniques. The system will allow the evaluation of yields and quality of the different microfibre fractions recovered from the wastewater filtering system, obtained by washing synthetic fabrics. This information, in turn, will allow us to evaluate the yield and quality of the diamonds and the scalability of the proposed up-cycling process. This will hopefully allow us to identify and characterize in qualitative and quantitative terms a microfibre recovery chain, in the due time to manage a waste flow that in a few years will certainly become very relevant for domestic users, but potentially also for industrial ones.

Overall, the research involves the creation of a laboratory prototype of the filtering system comprising two sequential objects: the mechanical filter, a cartridge to trap macro- and micro- fibres (organized into two phases of approximately 80 microns and 5 microns) and the biofilter, containing a microbial consortium, to mineralize/degrade nutrients and contaminants. The system will be designed to simplify the self-cleaning operations of the 80 micron filter, the recovery of the plastic microfibre fractions and the collection of the consortium biomass. Both filters will be designed following the principles of Life Cycle Design, based on minimization of resources, choice of recyclable materials with low environmental impact, optimization of product life, lengthening of the material life and facilitation of disassembly at the end of the cycle.

 

THE RESEARCH TEAM

TOR VERGATA

Laura Micheli
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Associate professor of Analytical Chemistry at the Tor Vergata Rome University, Department of Chemical sciences and Technologies. She developed an electrochemical approach to detect the composition of materials and produces silk-screened electrodes for their identification; in the project she is responsible for the development of a sensor to electrochemically identify and quantify the textile fibers collected from the filter in the washing machine wastewater.

Claudia Mazzucca

Associate professor of Physical Chemistry at the Tor Vergata Rome University, Department of Chemical sciences and Technologies. Her research activity is focused on the characterization/identification of materials using FTIR spectroscopy; in the project she is the responsable for the development of the identification method of textile fibers composition and of a specific database for all the possible textiles collected in the washing machine wastewater.

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Chiara Balestrieri
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Research Fellow of the Project. She is able to identify the composition of materials with an electrochemical approach, and works on the electrochemical detection of textile fibers present in washing machine wastewater using electrodes printed on screen and combined with portable and miniaturizable instrumentation.

Antonio Licheri

Research Fellow of the Project. He is involved in the characterization and determination of composition of textile fibers by FTIR spectroscopy. He collaborate to the set up of a dedicated database for the identification of textile fiber composition collected from the washing machine wastewater.

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POLITECNICO DI MILANO

Fiammetta Costa
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Associate Professor of Industrial Design, Politecnico di Milano, Department of Design. Her research deals with environmental design and user research. In the project she deals with ecodesign and life cycle of the filter system.

Attilio Nebuloni

Researcher in Architectural Design at Politecnico di Milano, Department of Design. His research deals with Computational Design and environmental sustainability applied to architecture. In the project he is involved in the study and development of the microplastic filter.

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Matteo Meraviglia
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PhD student in Design at the Politecnico di Milano, Department of Design. His research activity focuses on Biophilic Design and on the study of computational methods, approaches and tools for the design of living spaces integrated with nature. In the project he is involved in the study and development of the biofilter.