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Hygienic grey water container with reduced biofilm growth

Periodic Reporting for period 1 - HYGIEIA (Hygienic grey water container with reduced biofilm growth)

Reporting period: 2020-07-01 to 2021-06-30

The aim of the project is to design and manufacture a grey water container with reduced biofilm growth, based on appropriate surface coatings. HYGIEIA will evaluate two surface coating technology solutions which incorporate broad spectrum antimicrobial materials applied using wet and dry approaches: (1) paints, and (2) vacuum coatings by physical methods (PVD).
Broad spectrum antimicrobial capabilities (combating bacteria, mould, fungi…) shall be achieved through a low surface energy combined with a controlled final micro-roughness of the additivities. For HYGIEIA, the container which receives the coatings will be of plastic looking for benefits in weight and production cost. The container will be designed taking into consideration the rigidity and surface roughness requirements so as to provide the optimum conditions for application, adherence and durability of the antimicrobial coatings; while still complying with other requirements of the RTCA Do160 Rev. G.
The final aim of HYGIEIA is to apply the chosen antimicrobial solution to a container manufactured using the contemplated industrial approach to obtain demonstrators which in principle could be installed directly in an aircraft environment. HYGIEIA will also target to expand the market applications of the results to different industrial segments such as trains, ships, and other transport areas, as well as other areas where effective easy to apply water sanitation through wall coating may be relevant for water storage or transport.
The work performed during this period can be divided in two main blocks: (1) coupon and container design and manufacturing and (2) development of the coatings (PVD and MNP/Paints).

(1) The design of the container is being optimised in order to ensure the fulfilment of all the requirements described for the grey water re-use system components. Currently, and after including all the inputs of the rest of the partners and the TM, the final design of the container is almost finished.

(2a) Regarding the PVD coatings, two approaches have been considered: Metallic and ceramic layers. Several sets of PVD coatings have been deposited and characterised so far, including: roughness, chemical composition (GD-OES), thickness, adhesion (cross-hatch test), contact angle and antibacterial efficacy (JIS Z 2801:2010). Remarkable antibacterial efficacy and mechanical properties have been achieved.

(2b) Finally, the paints to be developed in the project should combine two main features (1) superhydrophobic behaviour and (2) antimicrobial properties. For this purpose, the HYGIEIA consortium has selected two references of paints (polyurethane and epoxy) and synthesised a wide range of metal oxide and metallic MNPS with different functionalisation treatments.
The results obtained in the project so far, are aligned with the expectations at this stage of the project, therefore, the main impacts envisaged by HYGIEIA are achievable:
- The technology envisaged for the biofilm-proof GWRS container, if successfully demonstrated its maturity, will have a significant economic impact in the aircraft OEMs and on the value chain, including SMEs. The three value pillars of HYGIEIA (intelligent design, antimicrobial coatings and robust testing methods) have a notable market demand, inside and outside the aviation industry.
- There is a growing concern on creating clean and safe surfaces justified by the current COVID-19 pandemic but also by the increasing resistance of micro-organisms to traditional products (antibiotics, etc), which is leading to difficult to cure infections. Antibaterial/microbial coatings or additives rapidly penetrating markets such as US, KR, JP or China, where the Public health protection systems are less powerful, and the treatment costs are mainly paid by people’s private resources. Market forecast of antimicrobial coatings up to 2-5 b$/year, with annual growths bigger than the 10% according to different market survey sources.
- Environmental is the major side driver of HYGIEA. 30% weight savings in flight represent a significant fuel saving consumptions when extrapolating the numbers to the vast amount of aircrafts operated annually. The biofilm-proof system proposed by HYGIEIA will lead to water saving during the flight, which is one of the most remarkable aspects of the project regarding the environmental point of view. Since grey water is up to now expelled directly from the aircraft via the drain mast, this water is lost; whereas, if reused, it may make it possible to carry up to 30% less potable water in the main sump; a considerable weight saving.
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