Ozone–Vacuum-Based Decontamination: Balancing Environmental Responsibility and Textile Waste

Abstract

This study explores the use of ozone decontamination as a sustainable approach for eradicating pathogens from various environments. Ozone, a highly reactive gas, demonstrates remarkable efficacy in eliminating bacteria, viruses, and fungi. Decontamination of textile materials using an innovative ozone treatment method conducted under vacuum conditions has been investigated. A hybrid apparatus comprising a vacuum and an ozone generator was employed for the decontamination process. Ozone decontamination offers environmental benefits by avoiding harmful by-products and minimising long-term environmental exposure. However, challenges include the need for proper equipment and training to ensure safety and effectiveness. This research underscores the promise of ozone decontamination as a powerful and eco-friendly method for pathogen eradication in textile materials with future developments in diverse settings.

1. Introduction

Textiles play a pivotal role across various industries, notably, in sectors such as healthcare and food service, where maintaining impeccable cleanliness is imperative to curtail the transmission of infections. However, textiles are susceptible to contamination by bacteria, viruses, and other perilous microorganisms, which can engender disease. Consequently, the implementation of effective decontamination strategies is imperative to uphold the well-being and safety of users. In recent years, there has been a burgeoning emphasis on textile and footwear recycling within the fashion industry, largely in response to their adverse environmental footprint. Notably, prior to recycling, these products necessitate thorough decontamination to eliminate the dissemination of bacteria and other noxious substances.

Textiles routinely harbour bacteria, encompassing Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa [1]. These bacterial strains are potential instigators of afflictions ranging from skin infections to urinary tract infections and respiratory diseases. Furthermore, textiles and footwear may also harbour fungal organisms, such as Aspergillus, Candida, and Trichophyton species [2], which can trigger various ailments, including nail infections, skin conditions, and respiratory tract disorders. Additionally, viruses can also persist in textiles and footwear, even if for relatively brief durations, retaining the capacity to remain active and propagate within crowded settings, such as gyms and sports training facilities [3]. Such viral entities encompass the influenza virus and the herpes simplex virus.

It is evident that textiles and footwear can serve as reservoirs of infection, harbouring pathogenic agents within their fibres. Therefore, meticulous attention and the application of cleaning and disinfection measures are imperative to eliminate the spread of diverse infections. The decontamination of textiles and footwear must assume importance in the textile waste recycling process.

The predominant utilisation of ozone in industrial settings is frequently linked to its antimicrobial attributes and its capacity to disintegrate organic compounds through oxidative processes. Ozone’s swift reactivity and its lack of selectivity in targeting various categories of microorganisms render it highly advantageous for a wide spectrum of applications [4,5,6,7,8,9]. The utilisation of ozone in garment processing, notably in laundry systems, has garnered significant attention in the past decade. This heightened interest is largely attributed to its potential for energy conservation when contrasted with conventional thermal laundry systems. Ozone exhibits distinct mechanisms when employed for the disinfection of microorganisms, exerting its disinfecting action by directly oxidising the constituents found in cell walls and membranes, including proteins and amino acids of spores [10,11]. This characteristic is particularly advantageous in large-scale applications, where expeditious processing and ensuring worker safety are important concerns.

Several studies throughout the specialised literature [5,12,13] have shown very high disinfection rates using ozone due to its fast reactivity and ability to penetrate difficult areas, textures, and substrates, including the textile industry as airborne disinfection for garments [14,15,16]. The study in [14] explored the effectiveness of using gaseous ozone to disinfect garments contaminated with E. coli bacteria, providing insights into optimising ozone disinfection of garments and highlighting factors such as ozone dosage, garment structure, arrangement, and recirculation for efficient disinfection. The research found that ozone was effective for disinfection, underscoring the importance of accurately determining the appropriate ozone dosage for efficient garment disinfection. Additionally, the study revealed that the weave structure of garments had a significant impact on ozone penetration, highlighting the necessity of systematic garment grouping to enhance disinfection in large-scale operations. Moreover, the arrangement and orientation of garments were shown to substantially influence ozone penetration and disinfection effectiveness and demonstrated that ozone gas is a valuable feature for small-scale disinfection chambers and for maintaining worker safety and commercial efficiency.

Ozone treatment versatility extends to various domains, encompassing its utilisation in medical and pharmaceutical products through the formulation of ozonated oils, commonly referred to as oleozone [17], and the food sector [18], as well as its incorporation into the textile industry [19]. Ozonated red pepper seed oil has been successfully applied to nonwoven fabrics for an antimicrobial effect, even against antibiotic-resistant micro-organisms. Another application of ozone involves the decontamination of medical waste in hospital settings [20]. Additionally, a study demonstrated that ozonated water effectively reduced the colony-forming units per millilitre of Candida albicans on denture plates [21]. Ozone finds further utility in disinfection procedures and in mitigating microbiota on toothbrush bristles [22], while serving as a fungicidal and detoxifying agent against aflatoxins [23]. Other research has illuminated the collaborative potential of ozone in combination with chlorhexidine 2%, which has enhanced efficacy against C. albicans [24]. Furthermore, ozonised olive oil has exhibited noteworthy antifungal properties in scientific investigations [25].

Tailoring decontamination methods to suit the nature and extent of contamination is vital, and the execution of this process must be undertaken with care to ensure both efficiency and safety. Another important aspect is that the act of purchasing and selling used clothes and garments has gained significant traction in contemporary society. This emergence of thrift culture has streamlined the accessibility of second-hand clothes and garments for individuals, often at significantly reduced prices relative to their original value. In the backdrop of the prevailing COVID-19 pandemic, it has become imperative to subject second-hand clothing to thorough disinfection protocols prior to their utilisation. Such comprehensive disinfection procedures are requisite due to the potential prior wear by individuals afflicted with infectious diseases. The meticulous implementation of disinfection measures, specifically under ozone treatment, assumes a leading role in attenuating the transmission of pathogenic microorganisms.

1.1. Cleaning Textiles

The process of cleaning relates to the removal of dirt, germs, and impurities from surfaces. It is important to note that cleaning does not entirely eradicate germs but serves to diminish their presence and the likelihood of infection dissemination. Effective cleansing of textile waste is of vital importance to mitigate these destructive effects and promote a circular economy within the textile industry. Within the realm of cleaning and hygiene, various concepts are commonly employed, including sanitisation, disinfection, and decontamination. While these terms share a common objective of sustaining a clean and safe environment, they hold distinctive meanings and objectives.

Sanitisation encompasses practices and measures directed at the improvement of public health and the preservation of cleanliness in diverse settings. Its focal point is the creation of hygienic conditions by eradicating visible impurities, such as dirt and debris, from surfaces, objects, or environments. Sanitation embodies a comprehensive concept that encompasses a spectrum of activities, including cleaning, waste management, personal hygiene, and the establishment of proper sanitation infrastructure. The primary aim of sanitation is the prevention of disease transmission by minimising the presence of pathogens and endorsing overall cleanliness and hygiene in both public and private spaces.

Conversely, disinfection pertains to the process of eradicating or reducing the population of microorganisms, encompassing bacteria, viruses, and fungi, to a level deemed safe for public health. The central objective of disinfection is the inhibition of infectious disease propagation through the targeted elimination of specific pathogens present on surfaces or objects. Disinfection methods commonly involve the utilisation of chemical agents, such as disinfectants, administered in accordance with prescribed guidelines to achieve effective microbial reduction [26].

Decontamination, on the other hand, is an all-encompassing process that entails the removal, neutralisation, or eradication of contaminants such as biological, chemical, or radiological substances from surfaces, objects, or environments. Decontamination strives to eliminate or limit potential risks associated with hazardous materials and pollutants. It is frequently conducted in settings characterised by a susceptibility to exposure to toxic or harmful substances, including laboratories, industrial facilities, or areas affected by chemical spills or biological incidents. The techniques employed in decontamination are contingent upon the nature of the contaminants and may encompass physical methods, chemical treatments, or specialised equipment, all orchestrated to ensure the secure elimination or neutralisation of hazardous substances and biological load.

In summary, disinfection primarily targets pathogens to block the propagation of infectious diseases, predominantly on surfaces and solid objects. In contrast, sanitation endeavours to promote public health by upholding cleanliness, while decontamination is centred on the eradication or neutralisation of hazardous substances and the reduction in biological contaminants across diverse environmental settings and contaminated elements. Microbiological aspects are even considered as possible recycling methods. There is a more recent biotechnological approach, in which enzymes and microorganisms are being investigated for their potential to selectively degrade specific components of textile waste, such as dyes and chemical finishes, while preserving the integrity of the fibres [27].

1.2. Textile Waste Decontamination

Cleaning textile waste presents several challenges. These include the presence of contaminants such as dyes, chemicals, and pathogens, as well as the variability in fabric composition and structural integrity. Traditional cleaning methods, such as water-based laundering, may not be suitable for all types of textile waste and may require significant energy and water consumption. Regarding decontamination, an important role is played in mitigating associated risks by either eliminating or diminishing the levels of contaminants. This process typically encompasses four primary methodologies: thermal decontamination, chemical decontamination, biological decontamination, and physical decontamination.

Thermal decontamination entails the utilisation of elevated temperatures to purge contaminants from textiles. Among the prevalent techniques, laundering, more specifically, washing of textiles at temperatures exceeding 60 °C with suitable detergents, stands out as an effective means for eradicating microbial contaminants [28]. Similarly, steam sterilisation, characterised by the exposure of textiles to high-pressure steam at temperatures surpassing 100 °C, proves highly adept at exterminating pathogens. Also, laundering at elevated temperatures exceeding 60 °C has demonstrated remarkable efficiency in reducing microbial contamination on textiles [29]. Steam sterilisation finds extensive application in healthcare settings due to its profound efficacy in eliminating pathogens from fabric substrates [30].

Chemical decontamination methods refer to using disinfectants or chemical agents for the elimination of contaminants. The disinfectant treatment method involves immersing or spraying textiles with disinfectant solutions, such as quaternary ammonium compounds or chlorine-based disinfectants, which effectively reduce microbial contamination [31]. Gaseous decontamination techniques, such as ethylene oxide (EtO) or hydrogen peroxide vapor (HPV) treatments, have been proven highly proficient in sterilising textiles. Disinfectant treatments exhibit noteworthy efficiency in mitigating microbial contamination on textiles, especially gaseous decontamination methods, like EtO and HPV, which excel in achieving sterilisation [32].

Biological decontamination methodologies harness biological agents to counter contaminants. A prominent approach involves enzymatic decontamination through the application of enzymes, such as proteases or lipases, which degrade and remove protein-based contaminants from textiles [33].

Physical decontamination techniques encompass the utilisation of ultraviolet (UV) light, ozonation, and ultrasonic cleaning to reduce contamination levels [17]. While washing was previously considered a part of physical methods, it now stands as a distinct category, with high-temperature washing being the sole effective method [34].

In the pursuit of achieving sustainable textile waste management, the adoption of environmentally responsible practices becomes predominant. This comprehensive approach includes various aspects, including waste reduction, reuse, and recycling, as well as the integration of eco-friendly detergents and energy-efficient cleaning technologies. Within this framework, decontamination assumes a focal role, involving the removal or neutralisation of contaminants present on personnel, equipment, and recycling materials. It holds utmost significance in ensuring the well-being and safety of individuals operating in hazardous waste sites and recycling hubs. Decontamination serves as a protective shield, guarding workers against unsafe substances and contaminants that may infiltrate and compromise the integrity of their protective clothing, respiratory gear, tools, vehicles, and other equipment utilised on site. Simultaneously, it acts as a safeguard for the entire workforce by minimising the transfer of harmful materials into clean areas. Moreover, decontamination plays a vital role in shielding the broader community by averting uncontrolled contamination transportation from the site [35].

The process of decontamination entails the removal of noxious substances from diverse surfaces, materials, or areas. It is worth noting that, in many instances, decontamination imposes the use of potent chemicals, which, regrettably, can also inflict damage upon the material being cleaned. Consequently, the identification of substances possessing decontamination properties without adverse effects on textile fibres becomes imperative.

Certain substances, fortunately, exhibit compatibility with textile fibres and can be used safely without causing any harm or alteration to the fibres themselves. These substances fall into distinct categories based on their origin, composition, and application.

Organic solvents like ethanol, methanol, and acetone are benign to synthetic fibres such as polyester, nylon, and acrylic due to their organic polymer composition. These solvents find utility in the manufacturing of synthetic fibres by dissolving polymer granules and forming a solution suitable for extrusion into filaments.

Inorganic compounds, specifically acids and bases, have the potential to inflict substantial damage on textile fibres. However, there exist exceptions within the realm of inorganic compounds. Water-soluble salts, oxides, and metals, for instance, do not adversely affect textile fibres and are often deployed in various stages of textile fabric processing, including dyeing, printing, and finishing.

Additionally, enzymes, which function as biological catalysts accelerating chemical reactions, do not pose a threat to textile fibres. They are consistently used in the textile industry for the removal of starch, scale, and other impurities from textile fibres in preparation for dyeing or finishing processes [36,37,38].

1.3. Ozone-Based Sanitisation

One of the increasingly prominent sustainable approaches in the realm of decontamination is ozone-based sanitisation. This methodology hinges upon the utilisation of activated oxygen, known as ozone, to eradicate deleterious pathogens from both surfaces and the ambient air. Ozone decontamination has gathered rising interest as a method for cleansing industrial and healthcare facilities, given its dual merits of effectiveness and environmental compatibility. This approach represents a highly efficacious means of eradicating bacteria, viruses, and other pathogenic entities within industrial and healthcare environments [39].

Ozone, constituting a highly reactive gas comprising three oxygen atoms, has found extensive utility as a disinfectant and decontaminating agent due to its potent oxidative and antimicrobial attributes [40]. Remarkably, ozone stands out as one of the most formidable oxidants known, boasting a substantially higher oxidative potential than chlorine or hydrogen peroxide. Moreover, it functions as an efficacious broad-spectrum antimicrobial agent, proficient in eliminating a spectrum encompassing bacteria, viruses, fungi, and protozoa [41]. Notably, ozone stands apart from other decontamination techniques, such as chemical disinfectants, by virtue of its innate and nontoxic nature, which leaves behind no harmful residues [42]. Furthermore, ozone exhibits proficiency in permeating hard-to-access regions, including small crevices or the internal components of medical apparatus, rendering it an ideal manner for decontaminating confined spaces. In addition to its effectiveness and safety profile, ozone-based decontamination confers several environmental advantages. Unlike harsh chemical agents, ozone engenders no production of noxious by-products that could detrimentally affect the ecosystem. Furthermore, ozone boasts a shorter half-life and exerts reduced persistence in the environment when compared to alternative disinfectants, thereby mitigating the likelihood of prolonged exposure to hazardous substances.

However, despite its manifold merits, ozone decontamination does present a series of challenges that warrant careful consideration to ensure its optimal efficiency. Foremost among these challenges is the required provision of suitable equipment and training. The careful employment of ozone generators is imperative to yield the desired ozone concentration, demanding comprehensive staff training in the operation of these devices to enforce rigorous safety protocols. Alongside this, concerns persist regarding the potential health repercussions of ozone exposure. While ozone remains safe under appropriate usage, elevated concentrations can induce respiratory irritation and other health issues. To remove such risks, meticulous training of personnel in the secure operation of ozone generators and other decontamination equipment is indispensable [43].

2. Materials and Methods

The experiments were based on 2 different groups of pathogens: a pathogenic bacterial strain, mainly E. coli, isolated from contaminated water samples, and a yeast strain—C. albicans, isolated from skin. The experiments were carried out in the microbiology laboratory of the Faculty of Chemical Engineering and Environmental Protection.

E. coli is a Gram-negative coliform bacterium with a rod-shaped cell from the genus Escherichia, commonly found in the lower intestine of warm-blooded organisms (endotherms). Most strains of E. coli are harmless, but some serotypes can cause serious intoxications in their hosts. The bacterium can be easily and inexpensively cultivated in the laboratory. The optimal growth of E. coli occurs at 37 °C, but some laboratory strains can multiply at temperatures of up to 49 °C. E. coli thrives in a variety of defined laboratory media, such as nutrient broth or any medium containing glucose, ammonium monobasic phosphate, sodium chloride, magnesium sulphate, dibasic potassium phosphate, and water [44,45,46,47].

C. albicans is an opportunistic pathogenic fungus responsible for the occurrence of candidiasis in the human body. C. albicans cells develop in various morphological forms, ranging from single-celled yeast to true hyphae with a parallel-sided cell wall alongside the plasma membrane. In its yeast form, C. albicans has dimensions ranging from 10 to 12 microns. Additionally, this species has the ability to form spores on pseudohyphae to survive when development conditions are unfavourable. On solidified culture media, C. albicans forms opaque colonies that can vary in colour from white to cream, depending on the composition of the medium and growth conditions [48,49,50,51,52].

In the conducted experiments, the following types of samples were used, made from cotton (CO), polyester (PES), spandex (SPX), and pig leather lining (PLL) in different blends (Figure 1):

• 1—Cotton + polyester + spandex (Figure 1a);
• 2—100% cotton (Figure 1b);
• 3—Pig leather lining (Figure 1c);
• 4—Polyester + spandex (Figure 1d).

Figure 1. Textile samples (4/4 cm): cotton, polyester, and spandex mix (a), 100% cotton (b), pig leather lining (c), and polyester and spandex mix (d).

Figure 1. Textile samples (4/4 cm): cotton, polyester, and spandex mix (a), 100% cotton (b), pig leather lining (c), and polyester and spandex mix (d).

The textile material samples (4/4 cm) were sterilised by autoclaving at 121 °C for 30 min to ensure their sterility.

2.1. Research Methods

In the conducted experiments, solidified culture media and liquid culture media with a general chemical composition that allows the development of a diverse range of microorganisms were used. Two solidified culture media and one liquid culture medium were employed, as follows:

• Yeast extract–glucose–peptone (YPG) agarised medium was used for the growth of C. albicans cultures, with the following composition (g/L): glucose—20; peptone—10; yeast extract—3; agar—15; distilled water—1000 mL; pH—6.8 to 7.0; sterilisation at 0.8 atm for 20 min.
• LB agarised medium (LA) was used for the growth of E. coli cultures, with the following composition (g/L): tryptone—10; yeast extract—5; NaCl—10; agar—15; distilled water—1000 mL; pH—7.0; sterilisation at 1 atm for 15 min.
• The liquid medium (nutrient broth) was used for obtaining the inoculum of each microbial strain and for their submerged cultivation. It had the following composition (g/L): glucose—20; meat extract—5; peptone—10; NaCl—5; distilled water—1000 mL; pH—7.0; sterilisation at 0.8 atm for 20 min. For conducting the experiments, the liquid culture medium was distributed into 150 mL Erlenmeyer flasks, each containing 50 mL.

2.1.1. Contamination of Textile Materials through the Submerged Cultivation Method

The method involves bringing the test samples into contact with the test microorganisms through cultivation in a liquid culture medium under aeration and agitation conditions for 48 h. The procedure is as follows:

• First, an inoculum is prepared by inoculating colonial fragments (5 × 10⁷ CFU/mL) of the bacterial or yeast strain into a liquid culture medium distributed in Erlenmeyer flasks. It is allowed to develop for 18–20 h under aeration and agitation conditions (Figure 2).

For the next stage, depending on the number of samples, 150 mL sterile bottles were prepared, into which 50 mL of liquid culture medium was added. Then, 5 mL of the cell suspension obtained in the previous step was added to each bottle, followed by the introduction of 2 textile samples for analysis in each bottle. All samples were set up in triplicate.

These prepared bottles were then incubated for 48 h under aeration and agitation conditions (240 rpm) to allow the growth of microorganisms and the contamination of the textile samples (Figure 3).

After 48 h of submerged cultivation of textile samples with pathogenic microbial strains, the textile samples were aseptically transferred from the contaminated medium with E. coli and C. albicans into sterile bottles. One specimen from each contaminated textile sample was washed several times (5 times) with sterile physiological saline, and the washing solution (final volume 50 mL) was used to perform decimal dilutions for each contaminated textile sample to assess the degree of contamination (Figure 4).

For this purpose, decimal dilutions were prepared by setting up 7 test tubes, each containing 9 mL of sterile physiological saline solution, for each textile sample. After the decimal dilutions were prepared, 1 mL of each dilution suspension was inoculated onto a specific agarised medium for each microbial strain and spread onto Petri dishes. These prepared plates were then incubated in a thermostat at a temperature of 37 °C for 24 h to allow the growth of microorganisms. Subsequently, the colonies that appeared on the surface of the culture media were counted at the dilution at which they could be quantified. The results obtained are presented in

Table 1. The initial degree of contamination of textile samples with pathogenic microbial strains.

Textile Sample	CFU/mL 1
	E. coli	C. albicans
1—CO + PES + SPX	33 × 104	28 × 104
2—100% CO	30 × 104	29 × 104
3—PLL	38 × 104	31 × 104
4—PES + SPX	35 × 104	30 × 104

¹ colony-forming unit per millilitre.

and illustrated in Figure 5.

2.1.2. Decontamination of Textile Materials through the Ozone Treatment Method under Vacuum

The decontamination process was performed using a hybrid device composed of a vacuum chamber, a vacuum pump, and an ozone generator.

The contaminated textile samples were placed between layers of textile materials (cotton, spandex, and polyester) to simulate the presence of biological contaminants within a cluster of materials (Figure 6).

The contaminated cluster was placed in a plastic chamber equipped with a unidirectional mechanical extraction valve connected to the vacuum pump to remove air from the chamber and the contaminated textile materials at a pressure up to 47.41 kPa (Figure 7).

The initial vacuum stage was chosen to eliminate possible gaseous influences on the research, to create an oxygen-depleted unfavourable culture environment, and to facilitate better ozone dispersion. This first stage of the disinfection process has the advantage of removing air from the treatment chamber and from between the layers and the interior of the textile products undergoing disinfection, thus ensuring ozone access deep within the fibres.

Ozone was produced by an ozone generator and introduced into the chamber at a concentration of 83.33 MgO₃/h, maintained for 30 min for one set of samples and 60 min for the second set of samples (Figure 8). The quantity of ozone used is minimal and the process does not require additional operations because the disinfection is carried out with a gas that depletes proportionally over time without producing residues and toxic byproducts.

3. Results

After decontamination, the effectiveness of the decontamination method used was checked. Textile samples of the four fabrics (two pieces) were washed with sterile saline solution (five times), with a total 50 mL of saline solution for each individual sample from 10 studied exhibits. A standard (etalon) sample could not be studied due to contamination risks and safety requirements. The wash waters have been used for serial dilutions and for the media insemination of solid culture distributed in Petri dishes. The inseminated plates were incubated in a thermostat at 37 °C for 24 h to allow the growth of microorganisms. Subsequently, the colonies that appeared on the surface of the culture media were counted in

Table 2. The influence of the decontamination method on the two microbial strains.

Textile Sample	CFU/mL 1
	E. coli		C. albicans
	30′	60′	30′	60′
1—CO + PES + SPX	4 × 102	2 × 10	6 × 102	2 × 10
2—100% CO	3 × 102	2 × 10	5 × 102	1 × 10
3—PLL	10 × 102	4 × 10	12 × 102	4 × 10
4—PES + SPX	7 × 102	3 × 10	7 × 102	5 × 10

¹ colony-forming unit per millilitre.

, Figure 9 and Figure 10, taking into account the dilutions made.

The colony-forming unit values vary from 3 × 10² to 12 × 10² CFU after 30 min of ozone treatment and from 1 × 10 CFU up to 5 × 10 CFU per millilitre after 60 min. The pig leather lining samples seem to keep a higher degree of contamination after the 30-min treatment for both E. coli and C. albicans strains, with respect to the other fabrics, but all samples reach a very low degree of contamination after the 60-min treatment.

Analysing the obtained data, a significant reduction in the number of bacteria is observed, even after a 30-min decontamination period. The numerical reduction can be observed with the naked eye, even after 30 min (Figure 11), and, by treating the samples for 60 min (Figure 12), there is an even more impactful reduction in the number of contaminating bacteria.

A notable decrease in the number of C. albicans colonies is detected, which depends on both the decontamination time and the specific textile sample analysed. Even from a basic perspective, the reduction in contaminants is substantial, with almost no colonies forming after the 60-min decontamination process.

All decontamination rates as shown in

Table 3. Comparison between the contaminated and the decontaminated samples on the two microbial strains after 30 min and 60 min of O₃ treatment.

CFU/mL 1		CFU/mL 1
E. coli	C. albicans	E. coli		C. Albicans
Initial contamination degree		30′	60′	30′	60′
1. 33 × 104	28 × 104	0.04 × 104	0.002 × 104	0.06 × 104	0.002 × 104
2. 30 × 104	29 × 104	0.03 × 104	0.002 × 104	0.05 × 104	0.001 × 104
3. 38 × 104	31 × 104	0.10 × 104	0.004 × 104	0.012 × 104	0.004 × 104
4. 35 × 104	30 × 104	0.07 × 102	0.003 × 104	0.07 × 104	0.005 × 104

¹ colony-forming unit per millilitre. 1—CO + PES + SPX; 2—100% CO; 3—P.L.L.; 4—PES + SPX.

and

Table 4. Degree of decontamination on the two strains after 30 min and 60 min of O₃ treatment.

Decontamination Rates (%)
E. coli		C. Albicans
30′	60′	30′	60′
1. 99.88	99.99	99.79	99.99
2. 99.90	99.99	99.83	99.99
3. 99.74	99.99	99.96	99.99
4. 99.80	99.99	99.77	99.98

1—CO + PES + SPX; 2—100% CO; 3—P.L.L.; 4—PES + SPX.

are over 99%. The lowest rates for the 30 min ozone treatment are 99.74% in the case of E. coli contamination, registered for the pig leather lining samples, and 99.77% in the case of C. albicans contamination, registered for the polyester–spandex mix samples. For the 60-min ozone treatment, all samples reached a 99.99% degree of decontamination for both strains, except the polyester–spandex mix sample infested with C. albicans, which registered a 99.98% degree of decontamination.

4. Discussion

The presence of pathogenic agents within textile waste is a matter of concern, primarily due to the potential threats it poses to public health. This underscores the imperative for the implementation of robust mitigation strategies and a heightened focus on research endeavours aimed at comprehending the intricate dynamics of pathogen transmission. Simultaneously, these efforts seek to develop efficacious prevention and control measures [53]. Through the concerted and diligent pursuit of these objectives, the potential health hazards stemming from textile waste can be effectively mitigated, ultimately fostering a safer and more sustainable environmental milieu. Unfortunately, without long-term sustainable strategies, even the most outstanding decontamination processes and rates might not be appropriately applied in various industries.

Mitigation strategies, aimed at curtailing pathogen contamination in textile waste, encompass a multifaceted approach. These encompass the adoption of stringent hygiene practices, including meticulous handwashing and the utilisation of protective attire, with the primary goal of minimising the inadvertent transfer of pathogens onto textile materials. Additionally, the implementation of highly effective disinfection modalities, such as heat treatment or the judicious application of antimicrobial agents, holds promise in diminishing pathogen viability within textile waste [54]. Furthermore, advancements in textile manufacturing processes, coupled with the innovation of antimicrobial textiles, offer substantial potential for reducing the prevalence of pathogen contamination in textile waste.

The effective cleaning of textile waste stands as a fundamental attempt in the broader context of mitigating the environmental impact generated by the textile industry and advancing towards a sustainable future. The amalgamation of innovative cleaning methodologies, when complemented by sustainable waste management practices, presents a promising avenue for addressing the multifaceted challenges associated with textile waste. By embracing and implementing these strategies, the textile industry assumes an instrumental role in fostering a circular economy, curtailing resource depletion, and championing environmental and social responsibility. In focusing on the imperative task of textile waste cleaning, this article contributes substantively to the formulation and evolution of eco-friendly and socially responsible textile waste management systems.

5. Conclusions

The efficient decontamination of textiles holds significance in safeguarding the well-being and safety of end users. Various approaches encompassing chemical, thermal, and physical decontamination methods have proven effective in the removal of microorganisms from textile substrates. The selection of a particular decontamination method hinges upon a multitude of factors, including the typology and abundance of microorganisms, the inherent nature of the textile material, and the considerations of cost-effectiveness and operational feasibility associated with the chosen decontamination approach. Consequently, a comprehensive risk assessment must precede the determination of an appropriate decontamination method.

Ozone-based decontamination emerges as an efficacious and environmentally responsible technique for eradicating hazardous pathogens within industrial and healthcare settings [55]. When executed with the requisite equipment and proficiency, this method serves to reduce the dissemination of infectious diseases while concurrently minimising adverse environmental repercussions. Given the persistent threat posed by COVID-19 to public health, the significance of ozone decontamination is ready to escalate, as it assumes an increasingly central role in disease prevention and control. The method’s effectiveness, encompassing broad-spectrum activity and the absence of detrimental residues, renders it an optimal choice for decontamination.

Ozone has exceptional microorganism eradication capabilities, rendering it an efficacious agent with antibacterial, antiviral, antifungal, and antiparasitic attributes [56,57]. This research adds to the specialised literature findings and shows a significant reduction in the number of both bacteria and fungus contamination at a 99.9% rate for the 30-min ozone treatment and a 99.99% rate for the 60-min treatment.

The most notable advantages of the hybrid vacuum–ozone treatment are:

• The disinfection process is dry and achieved using ozone gas;
• The disinfecting agent, namely ozone, is depleted without leaving residues;
• The ozone requirement is minimal because, by eliminating air from the disinfection chamber, it directly interacts with the treated products, achieving maximum concentration and a shorter depletion time.

One hypothesis stands out and needs further research: by vacuuming the disinfection chamber and removing air from both the disinfection space and between the textile products, as well as from the interior of the textile structures (knits and fabrics), ozone can efficiently act on pathogens regardless of their positioning.

Elevating awareness concerning the decontamination of textile waste marks the initial stride towards enhancing extant frameworks and directives, generating novel standards for operational protocols within waste management. These developments are acutely pertinent within the context of a post-pandemic environment that necessitates heightened regulation to forestall disease transmission and cross-contamination effectively.

All in all, the research has demonstrated that even a 30-min vacuum–ozone treatment shows impressive decontamination results for E. coli and C. albicans, but further research is needed to assess a minimum exposure time for decontamination and, ideally, over a wider range of contaminants.

6. Patents

Patent application at the Romanian State Office for Inventions and Trademarks (OSIM) no. A100556—Disinfection process for used textile products with pathogen agents contamination risk.