EP4237752A1

EP4237752A1 - Process for ventilating spaces or regulating air quality in spaces

Info

Publication number: EP4237752A1
Application number: EP21810109.5A
Authority: EP
Inventors: Willy Verstraete; Mariane Van Wambeke; Stijn BOEREN
Original assignee: Avecom Nv; Takeairlabs BV
Current assignee: Avecom Nv; Takeairlabs BV
Priority date: 2020-10-29
Filing date: 2021-10-27
Publication date: 2023-09-06
Also published as: BE1028762A1; WO2022090958A1; BE1028762B1

Abstract

The current invention concerns a process for ventilating a space or regulating the air quality in a space, where air is introduced or air is circulated via a ventilation system, with the air being brought into contact with sulphated polysaccharides. In addition, the invention concerns a carrier equipped with sulphated polysaccharides, and an air ventilation duct with such a carrier or with a nebulising installation with a suspension of sulphated polysaccharides suitable for nebulising. The invention also concerns the use of a suspension or aerosol with sulphated polysaccharides or the use of a carrier for regulation of air quality in a space, wherein viral particles present in the air are captured and inactivated.

Description

PROCESS FOR VENTILATING SPACES OR REGULATING AIR QUALITY IN SPACES

TECHNICAL DOMAIN

The invention concerns a process and means for the ventilation of area space or regulating the air quality in a space.

BACKGROUND

Ventilation or refreshing of air is replacing the air in a room which, for whatever reason, has been polluted or contaminated, with clean air. Ventilation is used to remove carbon dioxide, moisture, and contaminants, and to introduce fresh air. Air contamination can take various forms, such as dust, bacteria, fungal spores and viruses, chemical agents, and odours. Airconditioning (aircon), climate control, air treatment or air regulation are defined as regulating air in indoor spaces, for example regulating temperature and humidity. The application of a filtration system can also be used to purify air.

HVAC (heating, ventilation, air conditioning) installations in buildings, including non- residential buildings like offices, restaurants, hotels, shopping centres, care homes, schools and hospitals are usually equipped with (partial) air recirculation. Also, for example, aircraft, (cruise) ships, subways, etc. make use of recirculated instead of refreshed air, often for reasons of cost-saving.

If an HVAC installation is inadequately maintained and/or operated, it can contribute to the transfer of contaminated components. The installation can then recirculate the contaminated air and thereby increase the spread of the contaminant, even to other spaces connected by the same ventilation system. These ventilation systems may use filters, but there are generally dimensioned only for removing particles over 1 pm, making them inefficient for the removal of smaller particles, like viruses.

Viruses are between 20 and 300 nm in diameter, and cannot multiply outside the body of a host. They need a host cell in order to reproduce. A virus reproduces by infecting a bacterial, plant, or animal cell, and using the available replication mechanisms to replicate its own genetic material. Viruses that cannot infect a host (cell) will not be able to survive. Once outside of a host, the viability of a virus even gradually decreases over time.

However, a virus can be transmitted from one person to another. Possible methods of virus transfer are: direct transfer from person to person through droplet release (coughing, sneezing, talking) at short distance; indirect transfer through contact between the hands and contaminated (such as through droplets) surfaces and objects, followed by contact between the hands and the face; transfer via the air, following evaporation of the droplets, across longer distances and durations; and indirect faecal transfer following contamination of the air with virus particles from an infected individual's faeces.

When virus transfer goes via the air, these viruses can subsequently spread to other areas at an increased rate via interconnected ventilation systems. In addition, such ventilation systems can even create indoor circumstances that support viral viability, such as ideal humidity and temperature. One example of viral distribution via ventilation systems, is the pandemic spread of SARS-CoV-2 or COVID- 19, of which was shown that this spread was amongst other systems, mediated via the air and ventilation systems.

Filters that are suitable for removing small particles, like viruses, are called HEPA (high-efficiency particulate air) filters and are used in specific environments, like hospitals, surgical bays, and certain labs. According to applicable standards, a HEPA air filter must filter out at least 99.95% (European standard) or 99.97% (US standard) of particles with a diameter of 0.3 pm; with a higher filtration efficiency for particle diameters both larger and smaller than 0.3 pm.

Enforced air circulation like HEPA is more energy intensive, because of which this technology is not applied in office buildings, for example. Moreover, existing ventilation systems are not dimensioned to simply replace classic air filters with HEPA filtration systems.

One problem with common ventilation systems is, therefore, that these either do not stop viral particles; or, in the case of HEPA filtration systems, that these are energy-intensive, which has prevented the large-scale application of this technology.

Existing filter systems are described in US 2006 021 302. In addition, WO 2018 211 717 describes an exhaust gas cleaning agent. However, the filter and cleaning systems of US '302 and WO '717 do not offer an optimal solution.

There is still a need for an improved process for ventilating spaces or regulating space air quality. The current invention seeks to resolve the aforementioned issue.

SUMMARY OF THE INVENTION

The invention concerns a process in accordance with claim 1. In particular, the invention concerns a process for ventilating a space or regulation air quality in a space, where clean air is introduced or air is circulated through a ventilation system, and the air of the current invention is brought into contact with sulphated polysaccharides. The preferred embodiements of the process are shown in claims 2-14.

In an embodiment according to claim 2, the sulphated polysaccharides are provided on a carrier. These can be imbedded into a matrix, preferably oil-based matrix according to an embodiment of claim 3.

In an embodiment according to claim 7, oil-based aerosols are introduced into the air. Those aerosols then capture viral particles present in the air. In an embodiment of claim 9, these aerosols can contain sulphated polysaccharides.

In another embodiment according to claim 10, the suspension of sulphated polysaccharides is nebulised into an aerosol, preferably into a space or air ventilation duct.

In a preferred embodiment according to claim 13, the sulphated polysaccharides inhibit, inactivate and/or eliminate viral particles present in the air.

In a particularly preferred embodiment according to claim 14, the viral particles are from viruses selected from the family of influenza viruses, corona viruses, herpes viruses such as herpes simplex or cytomegalovirus, and paramyxoviruses like measles virus, preferably SARS-Cov-2.

The sulphated polysaccharides are preferably applied to a carrier, preferably a polyurethane carrier. The sulphated polysaccharides are preferably not brought into direct contact with people and/or animals inhaling the treated air.

A second aspect of the invention is that of a carrier with a porous surface, where the porous surface is equipped with sulphated polysaccharides, in accordance with claim 15. Embodiments of the carrier are shows in claims 16-17.

A third aspect of the invention is an air ventilation duct according to claim 18. Particularly, this is an air ventilation duct with a carrier equipped with sulphated polysaccharides or a nebulising installation for nebulising a suspension of sulphated polysaccharides.

A fourth aspect of the invention concerns a process according to claim 19. In particular, the invention concerns the use of a suspension or aerosol with sulphated polysaccharides or a carrier, as previously indicated, for regulating air quality in a space. The advantage is that viral particles in the air are captured and inactivated.

DETAILED DESCRIPTION

The invention concerns a process for ventilating a space or regulating air quality in a space through sulphated polysaccharides, a carrier with sulphated polysaccharides, an air ventilation duct with a carrier or nebulising installation, and use of a suspension or aerosol with sulphated polysaccharides or a carrier with sulphated polysaccharides for regulating air quality in a space.

Polysaccharides are carbohydrates comprised of ten or more monosaccharide units. These can be sulphated. Examples of sulphated polysaccharides include but are not limited to heparin, heparan sulphate, fucoidan, glycosaminoglycans, carrageenan, agar and ulvan.

All the aforementioned sulphated polysaccharides or mixtures thereof have been shown to be able to inhibit, inactivate or eliminate airborne viral particles that come into contact with these polysaccharides. In other words, these sulphated polysaccharides have an antiviral effect.

Therefore, the inhibiting or inactivating effects of the sulphated polysaccharides can ensure a reduction in the number of airborne viral particles exposed to these polysaccharides, and ensure a positive regulation of air quality. These polysaccharides can preferably be applied to a carrier, for example imbedded in a matrix applied to a carrier. In addition, oil-based aerosols can be introduced into the air. These aerosols can also contain sulphated polysaccharides. Aerosols which have captured viral particles can then, using the available polysaccharides, inhibit these particles, or contact a carrier equipped with the polysaccharides, thereby inhibiting, inactivating and/or eliminating the viral particles.

Unless otherwise specified, all terminology used in the description of the invention, including technical and scientific terminology, are sued to reflect their general meaning as understood by professionals in the technical area of the invention. To facilitate the assessment of the description of the invention, the following terms are explicated.

In the context of this document, "a", "the" and "it" refer to both plural and singular, unless the context would clearly suggest otherwise. For example: "a segment" means one or more than one segment.

The terms "encompass", "encompassing", "comprising of", "comprised of", "equipped with", "containing", "including", "with", are used synonymously and are inclusive or open terms that refer to the presence of what follows, and that do not exclude or inhibit the potential presence of other components, characteristics, elements, sections, steps from or described in the state of the art.

In a first aspect, the invention refers to a process for ventilating a space or regulating the air quality in a space, where clean air is introduced or air is circulated through a ventilation system, with the characteristic of exposing the air to sulphated polysaccharides.

"Air quality" refers to the extent of the absence of air contaminants, and depends on the presence of substances that can be harmful to human or animal health. In any space, or indoors, these harmful substances may include: chemical agents such as volatile organic compounds (VOCs) in perfumes, pesticides, paints or formaldehyde in fibre board; biological agents such as allergens from pets, dust mites, or plants, and any bacteria, fungi or mould, and viruses. In addition, certain gases, such as carbon monoxide, are also harmful.

"Ventilation" or "refreshing of air" means taking the air in a space which, for whatever reason, has been polluted or contaminated, and replacing it with clean air, thereby substantially improving air quality.

"Exopolysaccharides", abbreviated to EPS, are polymers with a high molecular weight, comprised of sugar residue, like (sulphated) polysaccharides, which are produced by micro-organisms and occasionally secreted into the surrounding environment.

In an embodiment, said sulphated polysaccharides are present on a carrier to which the air to be treated is exposed. Contact between the air and carrier with the sulphated polysaccharides, allows for a positive regulation of air quality.

Preferably, the carrier has been treated to be directly equipped with the sulphated polysaccharides; alternatively, these can be applied to the carrier through nebulising a suspension with these sulphated polysaccharides onto the carrier.

Nebulising a suspension with these sulphated polysaccharides onto a carrier is possible through a nebulising installation with a nebuliser. These nebulisers can be installed in or on an air ventilation duct of an air ventilation system. Nebulised suspension droplets must preferably have a diameter between 1 and 100 pm, more preferably between 2.5 and 50 pm. The suspension must preferably contain between 0.1 and 100 g/L, which is between 0.01 and 10 %, and more preferably between 1 and 50 g/L (0.1-5 %) sulphated polysaccharides.

In an embodiment, the suspension contains 0.01 - 10 % sulphated polysaccharides, more preferably 0.05 - 10 %, more preferably 0.1 - 10 %, more preferably 0.5 - 10 %, more preferably 1 - 10 %, more preferably 1.5 - 10 %, more preferably 2 - 10 %, more preferably 2.5 - 10 %, more preferably 3 - 10 %, more preferably 3.5 - 10 %, more preferably 4 - 10 %, more preferably 4.5 - 10 %, more preferably 5 - 10 %, more preferably 5.5 - 10 %, more preferably 6 - 10 %, more preferably 6.5 - 10 %, more preferably 7 - 10 %, more preferably 7.5 - 10 %, more preferably 8 - 10 %, more preferably 8.5 - 10 %, more preferably 9 - 10 %, more preferably 9.5 - 10 %.

In an embodiment, the suspension contains 0.1 - 5 % sulphated polysaccharides, more preferably 0.5 - 5 %, more preferably 1 - 5 %, more preferably 1.5 - 5 %, more preferably 2 - 5 %, more preferably 2.5 - 5 %, more preferably 3 - 5 %, more preferably 3.5 - 5 %, more preferably 4 - 5 %, more preferably 4.5 - 5 %.

In an embodiment, the suspension the contains between 0.01 and 2 %, or between 2 and 4 %, or between 4 and 6 %, or between 6 and 8 %, or between 8 and 10 % of sulphated polysaccharides.

If a nebuliser has been installed in an air ventilation duct, this will preferably be before (incoming air) and not after (outgoing air) a carrier. The carrier can be an air filter. If the nebuliser has been installed in front of a carrier/an air filter, the surface of the carrier/air filter will be provided with sulphated polysaccharides.

In another or further embodiment, said sulphated polysaccharides are imbedded in a matrix. Viruses present in de air are preferably captured by the matrix upon contact. This matrix can be any kind matrix known by a person skilled in the art. The matrix preferably does not release substances to the air which may be harmful to humans, animals and/or environments or said released harmful substances may only be released in amounts below legal thresholds. In addition, preferably this matrix is not be harmful in case of contact with the skin, digestive system and/or respiratory system.

In a preferred embodiment, said matrix is an oil-based matrix. A non-limiting example of such oil-based matrix is a matrix based on paraffin oil.

In another or further embodiment, this matrix is a hydrophobic matrix.

In another or further embodiment, this matrix is an adhesive substance.

An advantage of using an oil-based matrix and or other adhesive substance as a matrix is viruses are more easily captured by these matrices. Next, the imbedded sulphated polysaccharides can inhibit, inactivate and/or eliminate the viral particles.

The matrix preferably contains between 0.1 and 100 g/L, which is between 0.01 and 10 %, %, more preferably between 1 and 50 g/L (0.1-5 %) sulphated polysaccharides.

In an embodiment, the matrix contains 0.01 - 10 % sulphated polysaccharides, more preferably 0.05 - 10 %, more preferably 0.1 - 10 %, more preferably 0.5 - 10 %, more preferably 1 - 10 %, more preferably 1.5 - 10 %, more preferably 2 - 10 %, more preferably 2.5 - 10 %, more preferably 3 - 10 %, more preferably 3.5 - 10 %, more preferably 4 - 10 %, more preferably 4.5 - 10 %, more preferably 5 - 10 %, more preferably 5.5 - 10 %, more preferably 6 - 10 %, more preferably 6.5 - 10 %, more preferably 7 - 10 %, more preferably 7.5 - 10 %, more preferably 8 - 10 %, more preferably 8.5 - 10 %, more preferably 9 - 10 %, more preferably 9.5 - 10 %.

In an embodiment, the matrix contains 0.1 - 5 % sulphated polysaccharides, more preferably 0. 5 - 5 %, more preferably 1 - 5 %, more preferably 1.5 - 5 %, more preferably 2 - 5 %, more preferably 2.5 - 5 %, more preferably 3 - 5 %, more preferably 3.5 - 5 %, more preferably 4 - 5 %, more preferably 4.5 - 5 %.

In an embodiment, the matrix contains between 0.01 and 2 %, or between 2 and 4 %, or between 4 and 6 %, or between 6 and 8 %, or between 8 and 10 % sulphated polysaccharides.

In another or further embodiment, the carrier has been placed inside or on a ventilation duct. This ensure that the treated air that comes into contact with the carrier with the, preferably imbedded, polysaccharides is dispersed by the ventilation system.

In an embodiment, an oil-based matrix is nebulised across the carrier to prevent desiccation. This is preferably a paraffin oil-based matrix or a matrix as the one already provided on the carrier.

The carrier preferably has a porous surface to allow the transition of air. In this context, "porous" means having (small) openings (or pores). Porous materials have a large specific surface area. The "specific surface area" is a quality of a solid that indicates its total surface area per unit of mass or volume of this material. The larger the surface area, the more sulphated polysaccharides can be applied to the carrier, and the more efficiently these can be brought into contact with the air.

In a preferred embodiment, the carrier is an air filter. Air filter can be made of various materials including, but not limited to, paper, foam, cotton, spun (glass) fibre components, woven or unwoven synthetics, metallic mesh. In addition, the air filter may contain an active carbon component used to remove odours from the air. Air filters are porous, allowing air to transfer through, and, depending on the type of filter, blocking certain harmful substances, thereby improving air quality.

One specific example of air filters is HEPA (high-efficiency particulate air) filters, frequently used in hospital surgical bays, for example. A HEPA air filter removes at least 99.95% (European standard) of particles with a diameter of 0.3 pm from the air, with a higher filtration efficiency for particle diameters both greater and smaller than 0.3 pm. HEPA filters us a matrix of randomly ordered fibres, often glass fibre. As indicated, HEPA filters can block most viral particles.

Also in view of these HEPA filters, polysaccharides can be applied to or nebulised onto the surface using an air ventilation duct in front of the filter. The sulphated polysaccharides can be imbedded into a matrix, for example an oil-based matrix. Sulphated polysaccharides can be used here to inhibit, inactivate and/or eliminate viral particles blocked by the (HEPA) filter. Whatever few viral particles that manage to migrate through the filter will still be inhibited, inactivated and/or eliminated by the sulphated polysaccharides.

In another or further embodiment, the carrier is a polyurethane carrier.

In another or further embodiment of the invention, oil-based aerosols are introduced into the air. Preferably there are introduced into the air through nebulising an oil base into an air ventilation duct. The effect thereof is that those aerosols are able to capture viral particles in the air.

In another or further embodiment, these oil-based aerosols are paraffin oil-based aerosols.

In another or further embodiment, these aerosols are an adhesive substance.

The aerosols must preferably have a diameter between 1 and 100 pm, more preferably between 2.5 and 50 pm.

The oil base and oil-based aerosols must preferably not release airborne substances that may be harmful to humans, animals and/or environments; or any released harmful substances may only be released in amounts below legal thresholds. In addition, the oil base and oil-based aerosols must not be harmful in case of contact with the skin, digestive system and/or respiratory system.

In an embodiment, the oil-based aerosols contain sulphated polysaccharides.

Once the captured viral particles in the oil-based aerosols come into contact with the sulphated polysaccharides, the particles will be inhibited, inactivated and/or eliminated, as described above.

When viral particles captured in the oil-based aerosols come into contact with a carrier, as described above in any of the embodiments, such as an air filter with sulphated polysaccharides, the aerosols will come into contact with the carrier and (partly) be blocked by the carrier. The aerosols will preferably adhere to the carrier to some degree. The sulphated polysaccharides of the carrier and/or in the oil-based aerosols will then inhibit, inactivate and/or eliminate the viral particles.

In another or different embodiment, the oil-based aerosols will have been enriched with sulphated polysaccharides as described in each of the embodiments as described above or below. These sulphated polysaccharides must preferably be carrageenan.

The person skilled in the art will note that the current invention also concerns a carrier as described above, with a porous surface equipped with sulphated polysaccharides. These sulphated polysaccharides can be imbedded into a matrix, preferably an oil-based matrix as described above. The carrier is preferably an air filter.

The person skilled in the art will also note that the current invention also concerns an air ventilation duct, with a carrier as described above, or with a nebulising installation comprising a suspension to be nebulised of sulphated polysaccharides for nebulising the suspension onto a carrier.

By installing a carrier or nebulising installation in an air ventilation duct, the air quality of air moving through this installation can efficiently be regulated using sulphated polysaccharides.

An air ventilation duct is preferably used to restrict the amount of airborne virus, thereby reducing viral spread via ventilation systems and ventilation ducts. The person skilled in the art will note that the current invention also concerns the use of a carrier containing sulphated polysaccharides for regulating air quality in a space as described above. This allows airborne viral particles to be captured and inactivated.

In addition to applying sulphated polysaccharides to a carrier, it is also possible to nebulise a suspension with these polysaccharides into an aerosol. The suspension must preferably be nebulised into an aerosol inside the space or in an air ventilation duct. The suspension can be an oil-based suspension. A non-limiting example is a paraffin oil-based suspension.

The aerosols with sulphated polysaccharides preferably have a diameter between 1 and 100 pm, more preferably between 2.5 and 50 pm. The suspension must preferably contain between 0.1 and 100 g/L, which is 0.01 and 10 %, %, more preferably between 1 and 50 g/L (0.1-5 %) sulphated polysaccharides.

In an embodiment, the suspension contains between 0.01 and 2 %, or between 2 and 4 %, or between 4 and 6 %, or between 6 and 8 %, or between 8 and 10 % sulphated polysaccharides.

The nebulising suspension must preferably not release airborne substances that may be harmful to humans or animals. More preferably, this suspension must not be harmful in case of contact with the skin, digestive system and/or respiratory system.

A suspension can be nebulised into an aerosol using a nebulising installation with a nebuliser. These nebulisers can be installed in the space where the aerosols with sulphated polysaccharides are nebulised. A nebuliser can also be installed in an air ventilation duct of an air ventilation system, thereby accelerating and/or enhancing the distribution of the aerosols with sulphated polysaccharides.

If a nebuliser has been installed in an air ventilation duct, this may be, as previously described, before (incoming air) or behind (outgoing air) an air filter.. If this is behind the air filter, other air contaminants and harmful substances, such as dust or allergens, will be blocked by the filter first, allowing the aerosols to be distributed into more purified are. This allows the sulphated polysaccharides a better opportunity to come into contact with (harmful substances such as viruses in) purified or circulated air in the room.

The person skilled in the art will note that the current invention also concerns the use of a suspension or aerosol with sulphated polysaccharides for regulating the air quality in a space. The suspension must preferably contain between 0.1 and 100 g/L, which is 0.01 and 10 %, %, more preferably between 1 and 50 g/L (0.15 %) sulphated polysaccharides.

This invention also includes a suspension of aerosol with sulphated polysaccharides for inhibiting and/or eliminating airborne viral particles. The suspension must preferably contain between 0.1 and 100 g/L, which is between 0.01 and 10, %, more preferably between 1 and 50 g/L (0.1-5 %) % sulphated polysaccharides.

In an embodiment, the suspension contains 0.01 - 10 % sulphated polysaccharides, more preferably 0.05 - 10 %, more preferably 0.1 - 10 %, more preferably 0.5 - 10 %, more preferably 1 - 10 %, more preferably 1.5 - 10 %, more preferably 2 - 10 %, more preferably 2.5 - 10 %, more preferably 3 - 10 %, more preferably 3.5 - 10 %, more preferably 4 - 10 %, more preferably 4.5 - 10 %, more preferably 5 - 10 %, more preferably 5.5 - 10 %, more preferably 6 - 10 %, more preferably 6.5 - 10 %, more preferably 7 - 10 %, more preferably 7.5 - 10 %, more preferably 8 - 10 %, more preferably 8.5 - 10 %, more preferably 9 - 10 %, more preferably 9.5 - 10 %. In an embodiment, the suspension contains 0.1 - 5 % sulphated polysaccharides, more preferably 0.5 - 5 %, more preferably 1 - 5 %, more preferably 1.5 - 5 %, more preferably 2 - 5 %, more preferably 2.5 - 5 %, more preferably 3 - 5 %, more preferably 3.5 - 5 %, more preferably 4 - 5 %, more preferably 4.5 - 5 %.

In an embodiment of the invention, the sulphated polysaccharides are selected from the group of heparin, heparan sulphates, fucoidan, glycosaminoglycan, carrageenan, agar, ulvans, and combinations thereof.

Heparin, also known as unfractionated heparin (UFH), is a naturally occurring glycosaminoglycan, used as medication, particularly as an anticoagulant. It has also been shown to have direct antiviral activity against many encapsulated viruses and has anti-inflammatory capabilities. In addition, other glycosaminoglycans and heparan sulphate show antiviral capabilities.

Fucoidan is mainly found in various types of brown algae and seaweeds, like mozuku, kombu, rock weed, wakame or hijiki. In addition, fucoidan variants have been found in certain animals, like sea cucumbers. Fucoidans are supposed to have antioxidant, cognitive protective, anti-inflammatory, anti-angiogenic, anti- cancerous, anti-viral and anti-hyperglycaemic capabilities.

Agar is a polymer consisting of subunits of sugar galactose, and is a mixture of two components: linear polysaccharide agarose, and a heterogenous mixture of smaller molecules known as agaropectin. It creates the supporting structure for the cell walls of certain types of algae, and is released during cooking processes. These algae are known as agarophytes, and belong to the phylum of Rhodophyta (red algae). Agar can be used as a laxative, appetite suppressant, vegetarian gelatine replacement, soup thickening agent, in jams, ice-creams and other desserts, as a fining agent in brewing, and for stiffening paper and fabrics.

Ulvan is a sulphated polysaccharide found in Ulva spp. such as U. conglobate, U. lactuca and U. rigida, whose cell walls contain up to 29% ulvan based on dry weight. Ulvan has anti-oxidant capability, depending on its molecular weight. Ulvan in U. conglobate has significant anticoagulant effects. Alvan also has antiviral and immunomodulating capabilities, the potential of treating stomach ulcers, and is used in targeted drug delivery.

Carrageenan is the generic name of a family of gel-forming and viscosifying polysaccharides obtain through extraction from various types of red algae or Rhodophyceae. Examples include Chondrus, Gigartina and various types of Eucheuma. They are frequently used in the food industry for their jellifying, thickening and stabilising qualities, and as a vegetarian and vegan alternative to gelatine. These compounds have also been shown to have antiviral capabilities and the capacity to inhibit viral infection.

All of the aforementioned sulphated polysaccharides or mixtures have been shown to be able to inhibit, inactivate and/or eliminate airborne viral particles as soon as this air comes into contact with these polysaccharides.

In a preferred embodiment of the invention, said sulphated polysaccharides are selected from carrageenan such as, but not limited to, jota-carrageenan, kappa- carrageenan and lambda-carrageenan.

Carrageenan is classified into various types, such as A (lambda), K (kappa), i (jota), e (epsilon), p (mu)-type carrageenan, all comprising 22 to 35% sulphate groups. The names do not represent fixed chemical structures, but general differences in composition and degree of sulphation at specific locations in the polymer.

In a preferred embodiment, the sulphated polysaccharides inhibit, inactivate and/or incapacitate airborne viral particles.

As discussed above, it has been shown that various sulphated polysaccharides demonstrate antiviral activity. Antiviral activity is either "indirect antiviral activity", which disrupts the initial infection process, for example through inhibition of the replication in the cell, interference with viral adsorption and cell bonding and uncoating; or a "direct antiviral activity" in which viral-polysaccharide complexes are created, preventing the virus from bonding to a host cell, and preventing from infecting these cells.

The antiviral effect of carrageenan is further discussed below. Carrageenan is, among other things, a selective inhabitant for various encapsulated viruses, including human or animal pathogens such as human immunodeficiency virus, herpes simplex virus (HSV), human cytomegalovirus, Dengue virus, enterovirus, influenza, papillomavirus and human rhinovirus. Carrageenan works firstly by preventing viruses from entering or bonding with cells. These findings match the fact that carrageenan is similar to heparan sulphate, a viral cell bonding factor.

Studies with such viruses suggest that carrageenan has both direct and indirect antiviral activity. The indirect activity disrupts the initial infection process, such as by inhibiting replication in the cell, interfering with viral adsorption, and bonding to and uncoating from the cell. The antiviral activity of carrageenan is associated with the molecular weight and sulphated fraction as the antiviral effect only applies if the carrageenan can penetrate the tissue to protect the host-cells from the infecting virus. Direct virucidal effects attributed to carrageenan mainly focus on envelop- viruses, where the negatively charged carrageenan binds to viruses like Herpessimplex to create viral-carrageenan complexed to remove the envelope needed for bonding with the host-cell. The antiviral effect therefore depends on the type of carrageenan (incl. molecular weight and sulphation), the type of virus, and the type of host-cell.

The current process, as described above, will bring the air into contact with sulphated polysaccharides. These polysaccharides have antiviral activities, and will thereby at least inhibit, inactivate and/or eliminate part of the viruses in the air that come into contact with these sulphated polysaccharides.

The sulphated polysaccharides can be imbedded into a matrix to facilitate capturing viruses, after which the sulphated polysaccharides can inhibit and/or eliminate the viral particles.

The inhibiting/inactivating effect of the sulphated polysaccharides will reduce the amount of airborne virus coming into contact with polysaccharides, thereby positively regulating air quality.

The person skilled in the art will note that the current invention also concerns a process for reducing or limiting airborne virus in a space through ventilating or regulating the air quality in that space, by bringing the air to be treated contact with sulphated polysaccharides. These sulphated can be any type of known sulphated polysaccharides. The sulphated polysaccharides must preferably have antiviral activity.

The person skilled in the art will also note that viruses will also be inhibited and/or eliminated following contact with surfaces which were contacted by the air containing the sulphated polysaccharides, following nebulising in an air ventilation duct or directly in the space itself. More specifically, viruses not present in the air, but present in the space which contact the air with sulphated polysaccharides will also be inhibited and/or eliminated.

In addition, the person skilled in the art will note that the current invention concerns a process for reducing or limiting the spread of viruses via a ventilation system, where air (re)circulates through a ventilation system and is brought into contact with sulphated polysaccharides. These sulphated polysaccharides can be of any type of sulphated polysaccharides known by a person skilled in the art. The sulphated polysaccharides must preferably have antiviral activity.

In another embodiment, the viral particles are from viruses selected from the family of influenza virus, corona virus, herpes virus such as herpes simplex virus or cytomegalovirus, and paramyxovirus.

In another implementation, the viral particles are from viruses selected from herpes simplex virus, cytomegalovirus, measles, influenza-virus A, group 1 (H1N1), group 2 (H2N2), group 3 (H3N2), group 5 (H5N1, H5N2, H5N8) or group 7 (H7N7, H7N9); influenza B; influenza C; SARS-CoV-1; MERS-CoV; or SARS-CoV-2 (causes COVID- 19 or coronavirus disease 2019). In a preferred implementation, the virus is SARS- CoV-2.

In another or further embodiment, the viral particles are selected from a virus in the group of encapsulated viruses. These are viruses with a viral envelop or capsule including, but not limited to, viruses in the family of herpes virus, smallpox virus, hepadna virus, asfi-virus, flavivirus, alphavirus, togavirus, coronavirus, hepatitis delta virus, orthomyxovirus including influenza-virus, paramyxovirus, rhabdovirus, bunyavirus, filovirus and retrovirus.

In another or further embodiment, the viral particles are selected from a virus in the family of flavivirus, such as dengue virus, enterovirus, picornavirus such as rhinovirus and papillomavirus such as huma papillomavirus.

In an embodiment of the current invention, at least one of the listed sulphated polysaccharides was obtained from seaweed or produced microbiologically.

In an embodiment these sulphated polysaccharides were harvested from seaweed or produced microbiologically.

Extracting sulphated polysaccharides from seaweed generally means saccharide extraction. There are various extraction methods for sulphated polysaccharides known by a person skilled in the art. In general, these methods begin with a treatment of the seaweed tissue with an organic solvent to remove the majority of lipids and pigments, followed by proteolytic digestion and acid and/or alkaline extraction. An example of the extraction of sulphated polysaccharides from red algae comprises the use of NaOH, sonification followed by proteolysis.

Sulphated polysaccharides can also be produced microbiologically, for example by cultivating micro-organisms like bacteria known to produce sulphated polysaccharides in on or more bioreactors.

In an embodiment of the current invention, air brought into contact with sulphated polysaccharides can also be brought into contact with these sulphated polysaccharides through contact with micro-organisms emitting these sulphated polysaccharides. These micro-organisms preferably hold the status of Generally Recognized as Safe or GRAS, and are thus generally recognized as safe.

Micro-organisms suitable for the microbiological production of sulphated polysaccharides include amongst others sulphate-reducing micro-organisms and sulphide-oxidising micro-organisms, and/or combinations thereof. Examples are Desulfovibrio sp. including, but not limited to, Desulfovibrio vulgaris Marburg, Madison or Hildenborough), Desulfovibrio Gil, Desulfovibrio desulfuricans (Essex 6); Desulfotomaculum orientis; Desulfobacterium autotrophicum; Desulfobulbus sp.; Desulfotomaculum sp.; Desulfosporomusa sp.; Desulfosporosinus sp.; Thermodesulfovibrio sp.; Geobacter sp.; Archaeoglobus sp.; Thermocladium sp.; Thermodesulfobium sp.; Thiobacillus sp.; Thiothrix sp.; Halothiobacillus sp.; Acidithiobacillus sp.; Thioalkalivibrio sp.; Thiomicrospira sp.; Thermothrix sp.; Chlorobaculum sp. and Beggiatoa sp.

The person skilled in the art will note that it is also possible to use combinations and/or a consortium and/or mixture of different micro-organisms for the production of sulphated polysaccharides. These should preferably have at least one type of sulphate-reducing and one type of sulphide-oxidising micro-organism. These microorganisms can be naturally occurring or can be genetically modified, for example through mutagenetic processes or the introduction of foreign plasmids, genes or gene-fragments.

In embodiment, the listed sulphated polysaccharides are produced microbiologically through a multi-step method. In one step, sulphur compounds are converted into hydrogen-sulphide through sulphate-reducing micro-organisms under anaerobic circumstances.

Examples of sulphate-reducing micro-organisms include sulphate-reducing bacteria including, but not limited to, Desulfovibrio sp., Desulfotomaculum sp., Desulfobaterium sp., Desulfobulbus sp., Desulfotomaculum sp., Desulfosporomusa sp., Desulfosporosinus sp., Thermodesulfovibrio sp. and Geobacter sp. and sulphate-reducing archaea including, but not limited to, Archaeoglobus sp., Thermocladium sp. and Thermodesulfobium sp.

In a subsequent step, obtained hydrogen-sulphides are converted into biomass and biomass-derivatives through sulphide-oxidising bacteria under anaerobic circumstances.

Examples of sulphide-oxidising bacteria are Thiobacillus sp., Thiothrix sp., Halothiobacillus sp., Acidithiobacillus sp., Thioalkalivibrio sp., Thiomicrospira sp.; Thermothrix sp., Chlorobaculum sp. and Beggiatoa sp..

These conversions are preferably mediated by energy-dense gases.

"Energy-dense gases" are gases that are rich in chemical energy, like hydrogen, CO, H2S, PH3, CH4, volatile organic compounds, mixtures of such gases, gases produced by fermentation such as H2 or biogas, or through physical/chemical gasification processes, like syngas made with fossil or renewable resources or waste. Such energy-dense gases can serve as electron donors, and through biochemical conversions where these electrons are transferred to good electron-acceptor connections, added value microbial products can be created.

The listed multi-step conversions should preferably take place in one or more bioreactors.

The biomass and biomass-derivatives produced through the multi-step process contain various cellular wall components, including exopolysaccharides, particularly the sulphated polysaccharides used in the current invention.

The biomass can be used in the process of the current invention, where the sulphated polysaccharides, preferably from the cellular walls of the microorganisms, are brought into contain with the air. As previously described, this is possible through a nebulising installation and nebuliser in a space and/or air ventilation duct, or by applying these micro-organisms to a carrier like an air filter, preferably in a ventilation duct.

The sulphated polysaccharides can also be purified from the resulting biomass. To that end, the harvested biomass is preferably first treated. One step in the treatment process is the eradication of micro-organisms without affecting the quality of their polysaccharides. This is possibly through means including, but not limited to, pasteurisation, steaming, radiation, chemicals, or mechanical stress. During these or following steps, the biomass can be subjected to a drying or extrusion process while retaining the qualitative properties of the derivatives in or on the biomass. Next, the biomass derivatives, specifically the sulphated polysaccharides, can be purified.

These purified sulphated polysaccharides can then be used in the process of the present invention as discussed above.

In a preferred embodiment, the current invention concerns a process for ventilating a space or regulating the air quality in a space, with clean air being introduced or air recirculated through a ventilation system, where the air is brought into contact with sulphated polysaccharides on a carrier, preferably made of polyurethane, across or through which the air to be treated is brought, wherein the sulphated polysaccharides inhibit, inactivate and/or eliminate viral particles present in the air. The person skilled in the art will note that the current invention also refers to the use of a suspension or aerosol as described above in an embodiment comprising sulphated polysaccharides or a carrier described above in an embodiment for regulating air quality in a space, where viral particles present in the air are captured and inactivated.

What follows is a description of the invention using non-exclusionary example to illustrate the invention, which are not intended and should not be interpreted as a limit to the scope of the invention.

EXAMPLES

Example 1: sulphated polysaccharides applied to air filter

A porous carrier, specifically an air filter, is placed inside an air ventilation system. This carrier is equipped with sulphated polysaccharides, specifically with carrageenan, imbedded in a paraffin oil-based matrix. The matrix contains about 0.9 % sulphated polysaccharides. Various rooms are ventilated using the same ventilation system wherein the carrier/air filter was placed. The air is recirculated and introduced to the various rooms through the ventilation system. The sulphated polysaccharides on the air filter come into contact with the air in the rooms to be ventilated as it is processed through the air filter. Paraffin oil-based aerosols are introduced into the air through a nebulising installation. Viruses, including influenzavirus, coronavirus like SARS-Cov-2, herpesvirus and paramyxovirus present in this air are captured by the aerosols and transferred to the air filter via the air. There, the viruses come into contact with the carrageenan on the air filter, which inhibit the viruses. Viruses that can no longer infect a host following this inhibition will eventually not survive. The amount of virus present in the air, as well as the spread of those viruses through the ventilation system, is thereby reduced. A reduction of the amount of viral particles in the air also means a positive regulation of the air quality in the room.

Example 2: sulphated polysaccharides nebulised onto a carrier

A 4 % solution of sulphated polysaccharides, specifically a carrageenan solution, is nebulised onto a porous carrier, preferably an air filter, which has been placed inside an air ventilation duct. Various rooms are ventilated using the same ventilation system comprising this air ventilation duct wherein the carrier was placed. The air is recirculated and transferred through the various rooms through the ventilation system. The carrageenan on the air filter comes into contact with the air of the rooms that are ventilated when this air passes through the air filter. Paraffin oilbased aerosols with a diameter between 2.5 and 50 pm are introduced into the air through a nebulising installation. Viruses, including influenza-virus, coronavirus like SARS-Cov-2, herpesvirus and paramyxovirus present in this air are captured by the aerosols and transferred to the air filter via the air. There, the viruses come into contact with the carrageenan on the air filter, which inhibit the viruses. Viruses that can no longer infect a host following this inhibition will eventually not survive. The amount of virus present in the air, as well as the spread of those viruses through the ventilation system, is thereby reduced. A reduction of the amount of viral particles in the air also means a positive regulation of the air quality in the space.

Example 3: nebulising micro-organisms via an air ventilation duct into a space

A suspension of 3 % micro-organisms, specifically micro-organisms with GRAS status (Generally Recognized As Safe status) expressing sulphated polysaccharides, specifically expressing carrageenan, is provided. This suspension is nebulised into aerosols into an air ventilation duct as aerosols with a diameter between 1 and 100 pm. Various spaces are ventilated using the same ventilation system comprising the air ventilation duct in which this suspension was nebulised using a nebulising installation. The air is recirculated and transferred to the various rooms via the ventilation system. The micro-organisms expressing the carrageenan, which are nebulised via the suspension in the air ventilation duct, are brought into contact with the air in the rooms that are ventilated. Viruses, including influenza-virus, coronavirus like SARS-Cov-2, herpesvirus and paramyxovirus found in this air or surfaces that come into contact with this air, are exposed to carrageenan which inhibits them. Viruses that can no longer infect a host following this inhibition will eventually not survive. The amount of virus in the air, as well as spread of those viruses through the ventilation system, is thereby reduced. A reduction of the amount of viral particles in the air also means a positive regulation of the air quality in the space.

Example 4: nebulising sulphated polysaccharides into a space

A suspension containing 1.5 % sulphated polysaccharides, specifically carrageenan, in a paraffin oil is provided. This suspension is nebulised into aerosols using a nebulising installation in a space. Various spaces, amongst which the one wherein the suspension is nebulised, are ventilated using the same ventilation system. The air is recirculated and transferred to the various rooms via the ventilation system. The carrageenan, nebulised into the various spaces through the suspension, comes into contact with the air in the rooms which are ventilated. Viruses, including influenza-virus, coronavirus like SARS-Cov-2, herpesvirus and paramyxovirus found in this air or surfaces that come into contact with this air, are exposed to carrageenan which inhibits them. Viruses that can no longer infect a host following this inhibition will eventually not survive. The amount of virus present in the air, as well as spread of those viruses through the ventilation system, is thereby reduced. A reduction of the amount of viral particles in the air also means a positive regulation of the air quality in the space.

Example 5: Lab-scale testing of a solution to limit the spread of viruses in room ventilation systems a) Demonstrating the antiviral effect of carrageenan against the human corona virus

The purpose of this example is to demonstrate the antiviral effect of carrageenan on bacteriophages (viruses that infects the bacteria). These bacteriophages are MS2 and phi6.

MS2 infects E. coli, and is a non-enveloped, icosahedral virus. MS2 is generally more resistant to chemical disinfectants and also more resistant to environmental stressors such as temperature changes, dehydration and osmotic pressure. Phi6 infects P. syringae, and unlike MS2, but analogous to SARS-CoV-2 virus, it has an external lipid envelope and an internal nucleocapsid containing the genetic material (double-stranded RNA genome). Due to the presence of an enveloping lipid envelope, the phi6 virion is expected to be more sensitive to certain chemical treatments, especially with detergents and organic solvents that can remove the lipid membrane.

Solutions were prepared of 2 types of carrageenan, namely t-carrageenan and k- carrageenan. A solution of 2 g/L was made of both and 5 g/L of k-carrageenan was also made. These solutions were tested for antiviral activity against the human corona virus OC43. For this purpose, the cytotoxicity CC50 and the antiviral activity EC50 of the carrageenans were tested.

Cytotoxicity means damage or destruction of body cells (=cytes), usually by damage to the cell membrane. CC50 is the amount of the tested sample that causes 50% damage to the body cells. The higher the CC50, the better.

EC50 represents the concentration of the tested sample required to cause 50% inhibition of the virus-induced cytopathic effect. Cytopathic effect (abbreviated CPE) refers to structural changes in host cells caused by viral invasion. The infecting virus causes lysis of the host cell and/or inability to reproduce. Both effects occur due to CPEs. If a virus causes these morphological changes in the host cell, it is considered cytopathic. The lower the EC50 value, the more potent the antiviral connection. Table 1 gives a summary of the results. 3 series of tests were carried out, each time with the coronavirus but against different cell cultures (Huf-7, Hep3B and HRT-18G). Each measurement of cytotoxicity CC50 and of antiviral activity EC50 was performed in duplicate (exp. 1 and exp. 2) and averaged. The results that indicate antiviral activity are indicated in bold. Underlined and in italics are the selectivity index or SI values (MCC/EC50) that were equal to or greater than 5. It should be noted that the SI could not be accurately calculated if no cytotoxicity of the sample was measurable at the highest concentration of 0.2 g/L tested.

Remdesivir was used as a positive control for the corona virus. Its activity strongly depends on the cells used.

Table 1. Summary of the cytotoxicity measurement results and antiviral activity of various solutions of carrageenan ^a 50% Cytotoxicity Concentration, Determined by the Measurement of Cell Viability with a Colorimetric Formazan-based MTS Assay b 50% Effective concentration, or concentration causing 50% inhibition of a virus-induced cytopathic effect, determined by the measurement of cell viability with the fluorescent P.I. assay

The results showed that the tested carrageenan solutions (2 g carrageenan/L or 5 g carrageenan/L) have antiviral activity against certain corona viruses with EC50 values in the range of 20-100 pg/mL. b) Growing and measuring the number of bacteriophages

The procedure for growing the phages from stock purchased and for determining the number of phages (= titre) in a liquid, free of bacteria (filtration over 0.45 pm filter), was tested and further optimized.

The M2S phage was grown and then quantified.

For quantification, the plaque assay technique was used, in which the phages are grown on a double agar layer. In this case, the bottom layer only consists of solid agar (nutrient medium) and the top layer of soft agar in which the host bacterium, here E. coli, and the phages were added.

A dilution series was prepared beforehand from the phages. After about 1 day of incubation of the plates at 37°C, the plaques on the plates were counted. The results were expressed in PFU/mL of 'Plaque Forming Units'/mL. The plaques are the areas where there is no growth of E. coli due to the killing by the phage. The following steps are taken for this:

- A culture of the host bacteria is grown to high concentrations and a sample of phages is filtered over 0.45 pm (to remove contaminating bacteria) and diluted to the estimated concentration.

100 pL of the bacterial culture and 100 pL of a dilution of the phage sample are added to 4 mL of liquid soft agar.

- The soft agar is poured over a solid bottom agar layer in a petri plate and solidified.

- The double layer agar plate is incubated. During incubation, the bacteria will grow and overgrow the top layer. Phages present will infect and lyse the growing bacteria, forming circular clearance zones called a "plaque".

- The plaques are counted and based on the different dilution counts, it is possible to calculate how many phages are present in the sample.

An MS2 phage titre of 10¹⁰ PFU/mL was obtained in this way.

In addition to MS2 which infects E. coli, attempts were made to infect actively growing Pseudomonas cultures with phage phi6 and quantify the titre with a plaque assay, adapted for the optimal growth conditions of P. syringae. During successive optimization tests, the plaque assay was found to give the best results when the plates were incubated at room temperature (approx. 25°C). However, it was not possible to infect an actively growing P. syringae culture (liquid) with phi6, in order to obtain a phage stock this way. Phage cultivation was only possible by plaque assay and a phage stock could only be obtained by purifying the phage from the agar plates. As a result, only a phage titre of 10⁶ PFU/mL was obtained (in comparison: MS2 stocks typically contain 10¹¹ PFU/mL) which is relatively low for further testing. c) Experiments aimed at improved phage capture and sampling of the PU filter

Effect of PU filter pre-treatment on phage capture

Tests were performed to determine which treatment of polyurethane (PU) filters could provide improved capture/absorption of MS2 phages from the air flow. During the test, ~10¹⁰ PFUs (in 100 mL) were atomised in an air tube in the form of aerosols. Part of the atomized suspension remained on the wall at the entrance to the ventilation pipe, i.e. in front of the filter. The amount of phages in the airflow passing through the PU filter was thus lower than ~1O¹⁰ PFU.

After the test, the filter was removed and rinsed in 500 mL tap water. The MS2 phage titre in the rinse water was determined by a plaque assay to subsequently calculate how many phages were retained on the filter.

In a first series of tests, 6 separate test units were performed comparing 2 types of PU with different mesh sizes (Bulpren S52450 and Bulpren S28190). Both types of PU were used either untreated in the test or treated impregnated with 1% technical agar or impregnated with corn oil.

For the impregnation with 1% technical agar, the agar solution was warmed and poured hot over the PU, after which the PU was drained and cooled at 5°C for 15 min to solidify the agar. Then the PU-agar filter was dried at 30°C for 1 h. For the impregnation with corn oil, the oil was poured over the PU, after which the PU was drained and dried at 30°C for 20 min).

The results are listed in Table 2.

Table 2: Overview of the retained phages (titre, expressed in PFUs) on the PU filters of the first test series - Impact of pre-treatment of the PU filter

★Interrupted atomisation, which caused longer atomisation period.

The treatment of the PU filter with oil retained about 1.8 log (180 times) more aerosols and phages compared to an untreated PU filter.

In a second series of tests, 3 separate test units were carried out with the large mesh PU filter (Bulpren S52450) and with different types of oil, i.e. the corn oil, as used in the previous test series, and paraffin oil. In the control test 1, the PU filter was pre-treated with corn oil and in the other 2 tests, 2 and 3 this were done with paraffin oil. After impregnation of the PU filters and one-hour post-drying at 30°C, tests were carried out with the ventilation tube. In the 3 tests, an equal amount of phage suspension was atomised in the ventilation tube (same procedure as test series 1). In the case of test 1 and test 2, the sampling of the PU filter took place shortly after the spreading of the phage suspension (sampling after 15 min). In the last test, after the atomization of the phage suspension, ventilation was continued for a further 0.5 h before sampling the PU filter. The results of test series 2 are presented in Table 3.

Table 3: Overview of the retained phages (titre, expressed in PFUs) on the PU filters of the second test series - Impact of type of oil and drying of the PU filter due to longer ventilation

*The 100 mL phage suspension atomised for approximately 10 min

The results are a confirmation of the previous test series and show that the paraffin offers a good alternative to the corn oil. The numbers of phages retained on the PU filters of test 1 and 2 were of the same order of magnitude and higher than the control test (untreated PU filter) of test series 1 (see refer to Table 2). In the longer term, it is recommended to treat the PU filter with mineral oil instead of organic oil, since the mineral oil is less sensitive to unwanted growth of bacteria and fungi.

By maintaining the airflow for another 0.5 h, after the atomisation of 100 mL of phage suspension, dehydration and/or evaporation of the phage-rich aerosols on the PU filter occurred. This resulted in the killing of a significant fraction of the captured phages. The difference in PFUs between test 2 and test 3 was log 2.6 PFUs.

Effect of dehydration on captured phages on the PU filter

In a third series of tests, the effect of dehydration and/or evaporation of the retained phage-rich suspension on the paraffin -treated PU filter was confirmed. In this series, 2 tests were performed, each time with a paraffin pre-treated PU filter (large mesh). The test procedure was analogous to that described for the test series 1. In both tests of series 3, the sample of the PU filter took place after 15 min (shortly after atomisation of 100 mL phage suspension) but in test 1, the PU filter was immediately washed in water and this wash water was plated out, while in test 2 the PU filter was first dried (static drying process without air flow) for about 75 min at 30°C. Subsequently, this dried PU filter was also washed and the washing water was plated out. The results are presented in Table 4.

Table 4: Overview of the retained phages ( titre, expressed in PFUs) on the PU filters of the third test series - Impact of drying the PU filter, treated with paraffin oil

*The 100 mL phage suspension atomised for approximately 10 min

The significant decrease in the number of measured phages retained on the pretreated PU filter, after longer ventilation time in test series 2, was thus due to the death of these phages due to dehydration. In test series 3, the effect of static drying of the PU filter (without airflow) was tested and a log 1.9 PFUs decrease could also be determined by post-drying the PU filter.

Concluding, Example 5 confirms that carrageenan (solutions of 2 g/L or 5 g/L of 2 types of carrageenan) have antiviral activity against certain corona viruses with IC50 values in the range of 20-100 pg/mL.

Furthermore, Example 5 also showed that the treatment of the PU improved the absorption of the phages. When the PU filter was treated with oil, even lOOx more phages were retained. Compared to the amount of phages introduced at the entrance (~10¹⁰ PFU) and taking into account that part of the atomised phage suspension remained on the tube wall, it can be stated that more than 1 in 100 phages were collected on the PU filter pre-treated with oil. Furthermore, good adsorption of phages was obtained with both an organic oil (corn oil) and a mineral oil (paraffin, colourless). The latter is better suited for long-term use, as the mineral oil is less sensitive to the growth of unwanted bacteria and fungi on the pre-treated PU filters.

Finally, it is important to mention that the captured phages on the pre-treated PU filters are partially killed by dehydration (air flow through ventilation tube). In the tests performed, an order of magnitude log 2 (or a factor of 100) PFU decrease could be measured. The setup is thus extremely efficient. Example 6: Short-term testing of a solution to limit the spread of viruses, using a ventilation system

In subsequent experiments, a ventilation system was used comprising two 27x8 cm PU filters installed on manually adjustable fins. The main purpose of this ventilation unit was to test the trapping capacity of the treated PU filter when placed on fins at a certain angle (to minimize air obstruction) and with constant air circulation generated by the air conditioning unit of the ventilation unit. The system also made it possible to implement an additional PU filter (10mm thick), called Proxy 1, beyond the main filter without disrupting air circulation during the test, with Proxy 1, in order to capture the remaining phages in the airflow.

The slats could be closed, with the airflow becoming 0 m/s, either 1/4, 2/4, 3/4 or fully open. Results show that the position of the slats in the ventilation system was crucial for the virus trapping capacity of the developed filter system. This experiment showed that the filter must be opened 2/4 (approximately 45°) to ensure a virus capture of 92.0 +/- 4.7% (n=4) by the paraffin -coated PU filters.

This angle was then also maintained for further experiments.

Applying a pa raffin -based viscous coating does not only require a special nozzle, but also a supply of compressed air. Therefore, the purpose of the following experiments was to determine whether it is possible (by spraying) to apply an aqueous antiviral compound as a second coating layer over a paraffin (hand-coated) PU filter without adversely affecting the virus trapping capacity of the system. In summary, 20, 10 and 5 mL of the 5 g/L carrageenan suspension in water was post-treated on the pa raffin-treated filters already installed in the ventilation tube.

Higher volumes tested (10 and 20 mL) of the aqueous solution, manually sprayed over paraffin -coated PU filters, resulted in a decrease in the system's ability to capture viruses. However, when 5 ml of water-based coating was applied, the virus trapping capacity of the system was only slightly lower than shown in the previous experiments (89 versus 92%). In addition, applying the additional coating had no effect on airflow.

Another problem to be solved was those sulphated polysaccharides, such as carrageenan, all dissolve completely in water heated to about 65°C, but once the solution cools, the gel forms. On the other hand, when suspended in water, carrageenan deposits quickly, which can be disadvantageous when used in the spraying system.

In order to develop an atomization system that can reactivate both the virustrapping and the virus-killing capacity of the PU filter treated with paraffin and carrageenan (by reapplying the coating), a stable water-in-oil emulsion is therefore required. The final concentration of the active substance carrageenan remained the same as in all previous experiments, namely 5 g/L, but the water/oil fraction ratio was adjusted to 1 part water per 9 parts paraffin. Add 1.0% (w/v) of the emulsifier #16031 increased stability even at a higher temperature (10 days stable at 30°C).

As such, by adding 1.0% (w/v) of the emulsifier #16031, a coating formulation could be prepared that remained stable at 30°C for at least a week. After that time, a small separation of the water and oil phases was observed. However, gentle mixing was sufficient to restore the homogeneity of the emulsion.

It is worth noting that this formulation was prepared by mixing with a household homogenizer, therefore it is believed that by applying stronger shear forces during the preparation of this coating formulation, the stability can be extended. Nevertheless, the obtained emulsion showed a promising virus trapping capacity when applied in sufficient amounts to the 30 mm PU filters.

Concluding, we can state that a 100 mL of a formulation for coating the PU filter consisting of 90% (v/v) paraffin + 10% (v/v) water-based carrageenan (from 50 g/L stock solution) + 1 % (w/v) emulsifier #16031, which is sprayed on a PU filter (30 mm (28 x 28 cm), angle of 45°) removed 94% of the bacteriophages from the ventilation system. As a result, the formulation remains extremely efficient. This result is in agreement with the previous experiments, where 100 ml of coating was sufficient to guarantee high virus trapping through a vertically placed PU filter.

Furthermore, it is important to note that no significant detachment of the trapped phages from the treated PU filters could be measured, that no bacterial growth on paraffin treated PU foam was noted over a period of 2 months (static tests), and that no Legionella growth was observed on a treated filter which was incubated in the air duct for one month.

Example 7: Long-term testing of a solution to limit the spread of viruses, using a ventilation system

The purpose of this experiment was to continue the development of a stable paraffin/water-based carrageenan formulation and to evaluate the coated filter performance over a long period of time. In addition, the antiviral activity of carrageenan/paraffin emulsion against the porcine reproductive and respiratory syndrome viruses (PRRSV), a validated surrogate for the SARS-CoV-2 virus. Different combinations of filter coatings were also examined to select the most suitable solution from a practical, ecological and performance point of view. a) Further development of a stable paraffin-carrageenan emulsion

In a first step, an attempt was made to further stabilize the paraffin-carrageenan emulsion. However, the first promising emulsion of Example 6, obtained by mixing 1 part water with 9 parts paraffin and adding 1.0% (w/v) of the #16031 emulsifier, was found not to be stable for more than a few days. Therefore, in the further development of the paraffin-carrageenan emulsion, a number of emulsifiers, oil/water ratios and conditions were included.

Table 5. List of emulsifiers and other conditions tested to develop a stable paraffin / carrageenan emulsion.

* Emulsifier was dissolved in paraffin fraction unless otherwise specified ** in the total volume The main challenge in formulating paraffin with a carrageenan solution was the relatively high oil/water content and low solubility of carrageenan in water (up to 5 g/L). The limited water volume was pursued as it was found to have no negative effect on trapping. However, none of the 10: 1 or 10:2 oil/water ratio formulations resulted in a stable emulsion.

In addition, the addition of a stabilizer such as xanthan had a negative effect on emulsion stability contrary to expectations, probably due to the competition for water between xanthan and carrageenan molecules.

An increase in water content to an oil/water ratio of 2: 1, a higher concentration of an emulsifier and a controlled temperature during the mixing process resulted in an emulsion #24 that was stable for more than 3 months. Nevertheless, it should be noted that due to the limited solubility of carrageenan in water, the final concentration of this antiviral substance is 2.5 g/L, thus two times lower than the most effective dose against Sars-CoV-2, but it is still considered sufficient to combat this corona virus. b) Antiviral effect of the paraffin-carrageenan emulsion

The antiviral activity of carrageenan suspension was demonstrated in Example 5. However, the antiviral activity of carrageenan in oil emulsion has yet to be determined. Due to the complicated nature of the matrix (water-in-oil emulsion).

Recently, the porcine reproductive and respiratory syndrome virus (PRRSV) was validated as a suitable surrogate for SARS-CoV-2 (COVID19) virus. The procin Corona virus (PRCV) was used for further testing.

Six samples were analysed, including a control sample, a freshly prepared emulsion with or without additives such as zinc and citric acid, and an emulsion sample exposed to the environment for 40 days (static incubation of a coated filter in a petri dish). In summary, 250 pl of a paraffin-carrageenan emulsion sample was mixed with 250 pl of undiluted PRCV virus. The titration was performed after 4 hours incubation. A control sample (addition of medium) was used as the reference virus titre. The results of this analysis are presented in Table 6. Table 6. Activity of the paraffin-carrageenan emulsion against the PRCV model.

*Fifty-percent tissue culture infective dose (TCID50) is the measure for the infectious virus titre.

This endpoint dilution assay quantifies the amount of virus required to kill 50% of the infected hosts or cause a cytopathic effect in 50% of the inoculated tissue culture cells. Due to obvious differences in test methods and principles, TCID50 and pfu/mL or other infection test results are not equivalent.

The results show the following:

Due to the low solubility of carrageenan in water and the high oil/water ratio needed (to retain the virus from the coating), the final concentration of carrageenan in the tests was 2.5 g/L. Nevertheless, at least one log reduction (factor 10) in virus titre was observed in most samples within 4 hours of incubation.

Interestingly, an emulsion incubated for 40 days showed no antiviral effects against the PRCV model. Unexpectedly, fresh emulsion with citric acid showed a lower virucidal effect than the rest of the fresh emulsion samples. Surprisingly, the control sample showed a greater reduction than the carrageenan samples. Repetition of the test for sample 1 and sample 2 showed 93% and 97% killing effect, respectively. c) Long-term laboratory scale RIG 3 ventilation testing system experiments

The ventilation set-up of Example 6 was used for subsequent experiments.

Long-term experiment 1 : filter coated with the paraffin-carrageenan emulsion

The ventilation set-up of Example 6 was used for the first long-term experiment, where 30 mm PU filters were placed on slats that were open at position 2/4. The filters were then manually coated with 100 mL of formulation 1 (45 mL paraffin, 5 mL 50 g/L carrageenan in water and 1% emulsifier #16031). The first plaque test on Proxy 1 was performed immediately after the filter preparation. Subsequent phage doses were administered approximately once a week. During the control analysis, the test filter was removed from the air duct, but the slats remained open at position 2/4.

The results of this first long-term experiment showed that the virus trapping capacity of a filter freshly coated with the paraffin-carrageenan emulsion was 94%, which corresponds to the previously obtained results in Example 6.

The virus capture capacity decreased over time to 60% after a one-week incubation period and after two weeks the filter was no longer active. Reactivation of the filter by reapplying the coating (80-100 ml) restored virus trapping capacity (even up to 99%). Coating reactivation intervals appear to have a significant impact on filter performance, as longer pauses resulted in lower capture capacity after recoating.

No physical changes to the filter were observed after the experiment (50 days). The virus-catching ability of a filter that was already "old" could be restored after 50 days by applying a new coating.

It is important to note that for each bacteriophage challenge, 100 mL of virus suspension is atomised directly onto the filter, which may adversely affect the integrity of the coating, causing it to wash off or dilute. This could contribute to the lower virus trapping capacity observed during the first two weeks of the experiment. This "washing out/thinning" effect of the coating was previously observed in the evaluation of a two-layer coating with a water-based part on top (data not shown - Example 6).

Performance of a filter with two-layer coating

Since the paraffin/carrageenan emulsion gave variable results in the antiviral activity test and the formulation limited the carrageenan concentration to 2.5 15 g/L, it was decided to test a two-layer filter coat system, with a water phase under the paraffin layer. The aqueous base fraction (10 mL) consisted of a 5 g/L carrageenan solution and was manually sprayed over the filter. Subsequently, 80 mL of paraffin was also manually injected on top of the carrageenan layer. To check whether virus particles diffuse through the paraffin oil and reach the active substances, the product P solution (2 g/L) was used as a water-based fraction in one experiment.

As such, the two-layer filter coating system with carrageenan guarantees an MS2 virus trapping capacity of more than 90%, and reduced virus diffusion through the paraffin layer by 97%. The two-layer filter coating system can be just as effective in trapping and killing viruses as emulsion-based coating.

Long-term experiment 2: Two-Layer Coating Filter

In the view of the promising results of the experiment with a two-layer coating system, a long-term experiment was performed to evaluate the capture and virucidal capacity of the filter placed in the ventilation duct for several weeks and thus exposed to a continuous air flow. However, in this experiment, the incubated filters were challenged only once with a phage suspension to limit the "rinse out/dilution effect" of the coating observed in the first long term experiment described above.

In summary, multiple coated filters (water-based coating under the paraffin) were pre-provisioned and incubated in the air duct on a laboratory scale. After about a week of incubation, the filters were challenged with MS2 bacteriophages (100 ml virus suspension atomised into the airway), and the virus titre was calculated by plaque assay. If the filter tested does not exhibit at least 90% of the trapping capacity, a second filter (incubated the same time as the first) must be recoated and challenged with the MS2 bacteriophage suspension. If the reactivated filter does not show at least 90% of the trapping capacity, the experiment is terminated.

The claims of the 2nd long-term experiment are that the filtering power of at least 90% is maintained for at least a week, whereafter recoating the two-layer coating effectively regenerates the filtering performance. In contrast to the first long-term experiment, no "rinse-away/dilution" effect of the coating was observed in this experimental set up. d) Long-term laboratory scale RIG 4 ventilation test system experiments For the following experiments, a new (RIG 4) ventilation unit was used to evaluate the virus trapping capacity of the system, the design of which was based on the theoretical modelling. The aim of the modelling was to obtain the lowest possible obstruction of the airflow with the highest possible particle removal.

The RIG 4 of the ventilation system is equipped with the same air conditioning unit (ACU) and the same phage spray system as the RIG 3. However, the dimensions of the air duct and therefore also of the filter slats are larger. This 53 x 53 cm duct is equipped with 11 fixed fins that can accommodate custom elliptical PU filters. The main purpose of this ventilation unit was to test the trapping capacity of the treated PU filters when coated with paraffin, carrageenan and with a two-layer coating system, and to compare this with the theoretical values obtained by the model. The supplied system also made it possible to run a Proxy 1 as previously discussed, without disrupting air circulation during the tests. In addition, particulate mass (PM) and pressure sensors were also installed in the ventilation unit of RIG 4.

Determining the trapping capacity of the virus trap

As with the experiment performed in the past, 100 mL of bacteriophage suspension was atomised into the vent tube at a flow rate of approximately 15 mL/min and an airflow of approximately 2.0 m/s (measured at the exit of the ACU). To ensure the greatest possible accuracy, one phage suspension was prepared for each test (always the same for both the control and the test) and the ventilation tube was cleaned between tests. The principle of determining the virus trapping capacity in the following tests is based on the application of a proxy filter. Briefly, the virus trapping capacity of a filter unit is determined as the difference between the bacteriophage titre recovered from a proxy filter when no virus trap was present in the air duct (Control) and from a proxy filter when the PU foam slats were installed in the ventilation duct (Test). Due to the large size of a proxy filter (52 cm x 52 cm), 1000 mL of water (instead of 500 mL) was used to extract phages from the filter before the plaque test.

In the first test series, the virus trapping capacity of an uncoated "dry" virus trap was evaluated. In addition, the influence of empty slats on the virus titre recovered from a proxy filter was also tested. Interestingly, the simple placement of the filter cassette without PU filters already created a mechanical barrier that stopped almost 50% of the viruses atomised into the air duct. In addition, the installation of uncoated PU filters ("dry filters") on the slats resulted in a greater than 99% reduction in virus titre recovered on the proxy filter.

In the second test series, the virus trapping ability of the PU filters coated only with a 5 g/l carrageenan solution was evaluated. Three different volumes of carrageenan coating were used: 150, 50 and 15 ml. The ability to capture viruses through carrageenan coated PU filters was correlated with the volume of the coating applied, as 1.5 log reduction in phage titre was observed at the highest volume tested (150 mL). With only 15 mL of coating, the virus particle log reduction was approximately 2.0 log values, which is consistent with the results obtained for the "dry" filters.

In the third test series, the effect of the paraffin coating on the virus trapping ability of the new PU filter was evaluated. In these experiments, the paraffin coating consisted of a mixture of solid and liquid paraffin that was applied by immersing PU foam in the preheated paraffin mixture. Once the coating had cooled and solidified, the PU filters were applied to the 11 slats. The highest trapping power observed in this experiment was over 99.9%, and the average virus titre log reduction from three tests was 3.0. This nearly 1 log greater reduction in virus titre recovered from the proxy filters placed behind a paraffin -coated filter than those with carrageenan or uncoated, demonstrated that paraffin is highly effective at capturing airborne particles that flows through the ventilation.

However, the purpose of this project is to develop a high-efficiency filter that not only removes viruses effectively, but also renders them inactive. Therefore, in the fourth test series, a two-layer filter coating system was analogous to that of Example 6, but this time the water phase, which consisted of a 5 g/L carrageenan solution, was manually sprayed over the PU filters previously coated with solid paraffin. The results of these experiments confirmed that the water-based solution negates the effectiveness of paraffin in trapping viruses. In addition, as noted above, the more water-based coating is applied, the less viruses are captured, but these differences were negligible in the tested volume range of the carrageenan solution (100 - 15 mL).

Since in all experiments with or without paraffin, when carrageenan was also used, the maximum virus trapping capacity of the PU filters on 11 slats was approximately 99%, it was decided not to use paraffin as a component of the filter coating any more. Forgoing paraffin will also have beneficial effects on the total cost of the final product, as the special cleaning and recovery of filters will no longer be necessary.

In summary, this experiment showed that the virus trapping capacity of uncoated filters was 99.1%, and the maximum virus trapping capacity of carrageenan coated filters was 98.9%. In addition, an up to 3 log reduction in virus titre was observed for the paraffin coated filters, and the maximum virus trapping capacity of two-layer coated PU filters was 99.2%.

Further experiments showed that the presence of PU filters reduced the amount of particulate matter in the air passing through the filter, that the presence of PU filters reduced the concentration of total volatile organic compounds (TVOC), and that there was no large effect on the pressure and thus on the perceived air volume in the ventilation duct. Finally, it was also observed that there was a slight decrease in airspeed due to the installed filters. For the latter, however, there was no difference between uncoated and carrageenan-coated air filters.

It is believed that the present invention is not limited to the embodiments described above and that some modifications or changes may be added to the described examples without revising the claims added.

Claims

1. Process for ventilating a space or regulating air quality in a space, wherein air is introduced or air is circulated via a ventilation system, characterized in that that the air is brought into contact with sulphated polysaccharides.

2. Process according to claim 1, wherein the sulphated polysaccharides are applied to a carrier across or through which air to be treated is passed.

3. Process according to claim 2, wherein the sulphated polysaccharides are imbedded in a matrix, preferably an oil-based matrix.

4. Process according to claims 2-3, wherein the carrier is positioned in or on a ventilation duct.

5. Process according to any of claims 2-4, wherein the carrier has a porous surface.

6. Process according to any of claims 2-5, wherein the carrier is an air filter.

7. Process according to any of the previous claims, wherein oil-based aerosols are introduced into the air, preferable via nebulising an oil-base inside an air ventilation duct.

8. Process according to claim 7, wherein the oil-based aerosols are paraffin oilbased aerosols.

9. Process according to claims 7-8, wherein the oil-based aerosols contain sulphated polysaccharides.

10. Process according to claim 1, wherein the suspension of sulphated polysaccharides is nebulised into an aerosol, preferably within a space or in an air ventilation duct.

11. Process according to any of the preceding claims, wherein said sulphated polysaccharides are selected from the group of heparin, heparan sulphates, fucoidan, glycosaminoglycans, carrageenan such as jota-carrageenan, kappa- carrageenan or lambda-carrageenan, agar, ulvans and combinations thereof, preferably said sulphated polysaccharides are selected from carrageenan like jota-carrageenan, kappa-carrageenan and lambda-carrageenan.

12. Process according to any of the preceding claims, wherein at least one of said sulphated polysaccharides is harvested from seaweed or produced microbiologically.

13. Process according to any of the preceding claims, wherein the sulphated polysaccharides inhibit, inactivate and/or eliminate viral particles present in the air.

14. Process according to claim 13, wherein the viral particles are from a virus selected from the family of influenza-virus, coronavirus, herpesvirus such as herpes simplex of cytomegalovirus, and paramyxovirus such as measles virus, preferably SARS-Cov-2.

15. Carrier with a porous surface, characterized in that the porous surface of the carrier comprises sulphated polysaccharides, preferably selected from the group of heparin, heparan sulphates, fucoidan, glycosaminoglycans, carrageenan, agar, ulvans and combinations thereof.

16. Carrier according to claim 15, wherein said sulphated polysaccharides are imbedded into a matrix, preferably an oil-based matrix.

17. Carrier according to claims 15 or 16, wherein the carrier is an air filter.

18. Air ventilation duct with a carrier according to any of claims 15-17, or with a nebulising installation comprising a suspension of sulphated polysaccharides to be nebulised.

19. Use of a suspension or aerosol comprising sulphated polysaccharides, or a carrier according to any of claims 15 or 17 for regulating air quality in a space, wherein viral particles present in the air are captured and inactivated.