Research on Sterilization Laundry Technology

Abstract: This article mainly introduces the current development status of the laundry industry at home and abroad. By comparing the commonly used disinfection and sterilization methods in China's laundry industry, many problems are found. Combining the domestic and international situation and development trends, a new sterilization and energy-saving laundry technology is introduced. This technology uses ethylene oxide and carbon dioxide to produce a stable sterilization gas for pre-washing sterilization of clothes, allowing clothes to be washed under sterile conditions. It creatively combines ethylene oxide sterilization, wastewater treatment recycling water, and solar energy technology for the laundry industry. It not only improves the internationally advanced laundry production line but, more importantly, improves the internationally advanced laundry industry management standards and service concepts. This technology is environmentally friendly and reliable, has good industrialization prospects, large market demand, and has an immeasurable driving effect on the development of the entire laundry industry and even society.
 
Laundry is an indispensable basic part of people's daily life and a lifelong essential element for pursuing a healthy life. With the rapid improvement of living standards, people increasingly understand that health is the greatest treasure in life, and clothing has long evolved from merely providing warmth to entering the era of health preservation. People not only pay attention to the health of their diet and daily routines but also place greater emphasis on the health of their clothing. In the 1970s, the United Nations World Health Organization defined health in the World Health Charter as follows: "Health is not only the absence of disease but also a complete physiological, psychological state and social adaptability, all of which can be reflected through a person's clothing..." This shows that a person's health is closely and intrinsically linked to their clothing. The attention people pay to laundry and health marks social progress. In some foreign cities' business activities, some shops often close for various reasons, but two types of shops can remain: bakeries and laundries. This is because bread can feed people to continue living, and laundries make people's lives more decent and beautiful. In today's social life, laundry has become as important as food and is an essential part of human social life. From ancient times to the present, washing clothes has been a household chore that is hard to avoid. Before the emergence of the laundry industry, for many people, it was not as enjoyable as pastoral poetry depicted. Hand scrubbing, beating, rinsing, and whipping—these repetitive simple physical labors often left people feeling tired and exhausted. However, with continuous scientific and technological progress, laundry is no longer a headache. People no longer need to repeat simple physical labor, and human hands have long been liberated. The laundry industry started earlier in some developed countries in Europe and America, as well as Japan and Singapore, and is now widespread. Abroad, no one regards laundry work as simple or undignified; it is an industry involving knowledge from machinery, chemical engineering, textiles, and other disciplines, creating huge wealth for society and bringing material enjoyment to humanity.
However, while the laundry industry brings convenience to human life, many problems exist, such as high water and electricity consumption, the environmental impact of detergents in wastewater, and focusing only on clothing cleanliness while neglecting disinfection effects. The laundry industry requires a large amount of water daily; a small laundry factory uses more than 50,000 tons of water annually, causing significant water resource waste. Laundry residues and wastewater are not strictly treated, which can cause great environmental harm. Additionally, a large amount of electricity is needed for drying and ironing washed clothes; a small laundry factory consumes more than 100,000 kilowatt-hours annually, causing huge electricity waste. Traditional laundry emphasizes cleanliness but downplays disinfection. Because the source of washed clothes is complex, cross-contamination easily occurs during washing. According to tests by the Qingdao Center for Disease Control, post-wash clothing contamination rates for Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and hepatitis B virus are 28%, 30%, 8.9%, and 12.5%, respectively, posing great harm to human health. Therefore, thoroughly solving cross-infection of washed clothes, saving water and electricity, and preventing pollution are difficult problems and research focuses in our laundry industry, fundamentally benefiting the country and people. Currently, sterilization and energy-saving laundry has become a hot topic in public health concepts. Comprehensive research on sterilization and energy-saving laundry technology will create huge wealth for society and bring material enjoyment to human health. It is a milestone for improving laundry business concepts and expanding the laundry market depth.
The United States has long used solar medium-temperature systems in industrial processing. In the 1980s, California built a 600-square-meter solar medium-temperature device that could produce steam at 170 degrees Celsius, meeting 75% of a laundry's steam needs. In Bolingbrook, Illinois, 61-year-old Tom Benson operates what he calls the "world's largest self-service laundry"—Laundromat. He installed 24 large solar collectors on the laundry roof. These provide the steam needed for the laundry. Benson enthusiastically calculates the details: with 145 washing machines open 24 hours, the monthly energy cost savings amount to $2,000, which is key to maintaining the laundry's financial success.
Although domestic and foreign businesses pay more attention to energy-saving technological transformations and the cleanliness of laundry surfaces, they neglect water-saving, environmental protection technological transformations, and sterilization of clothes, failing to achieve truly environmentally friendly and healthy laundry. Yet environmentally friendly and healthy laundry has been hyped extensively, even washing machines have begun to associate with health. Using silver nano antibacterial materials, ozone water, chlorine-containing bleaching water, sterilization and deodorization integrated washing and drying machines, etc., but unfortunately, until today, health-related hype in the laundry industry remains unregulated, and consumers remain skeptical and confused, unable to reduce doubts about businesses' health concept hype. After all, health functions can only serve as auxiliary features of products; the health concept merely adds product selling points and functions, and consumers cannot truly experience these benefits. Whether it is human development and self-value realization or social development participation and achievement enjoyment, everything must be premised on health. Without a healthy body and mind and healthy clothing, nothing can be discussed. Therefore, pursuing laundry and health is pursuing civilization and progress.
China is a country with a population of 1.3 billion, providing vast development space for the laundry and dyeing industry. According to the China General Chamber of Commerce, the number of outlets in China's laundry industry has grown to more than 1.18 million in just a few years, with over 3 million employees. As the laundry industry is an emerging sector, it has its shortcomings, such as employees lacking rigorous technical training; relatively outdated washing technology and equipment; laundry shops facing seven types of hazards: mechanical, electrical, thermal, fire, explosion, solvent, and pollution hazards. Although foreign countries have more advanced washing equipment and include disinfection processes in their washing procedures, the disinfection effect does not reach sterilization, and water and electricity consumption is high. These factors have led businesses to focus more on energy-saving technological upgrades, especially emphasizing laundry technology, washing quality, and management culture. Currently, the domestic laundry market is just starting, and the washing equipment is far behind that of developed countries abroad. Most domestic laundries still use first- and second-generation washing machines, with wastewater discharged arbitrarily, causing water resource loss and environmental pollution. Most laundries do not disinfect washed clothes, and a few that do use toxic, irritating, corrosive disinfectants that pollute the environment and have poor disinfection effects, causing cross-contamination of clothes from various sources during washing. The backward equipment, high water and electricity consumption, and serious environmental pollution are the main obstacles to the development of the domestic laundry industry.
Currently, the commonly used disinfection and sterilization methods in the laundry industry include ozone, ultraviolet light, and liquid detergent disinfection, but each method has certain drawbacks. Ozone can cause clothes to fade, has limited sterilization effects, and cannot effectively kill hepatitis B virus; ultraviolet light has poor penetration and incomplete sterilization; liquid detergents have a certain corrosive effect on clothes, and the discharged liquid may cause environmental pollution. There are few domestic brands of liquid disinfectants for clothes on the market, mainly focusing on hygienic washing, generally with poor bactericidal activity, requiring large doses and high costs. Most clothing disinfection products on the market are foreign brands, mainly using chlorophenol compounds as the main disinfectant and bactericidal ingredients. Long-term use has shown significant skin irritation to humans and strong corrosiveness to metals, affecting metal utensils and the environment to varying degrees. Extensive research and investigation have found that these disinfectants have a narrow bactericidal spectrum, require large actual usage amounts, and are costly, so these compounds are gradually being phased out. Recently developed disinfectant detergents are mostly oxidants, such as oxygen bleach and chlorine-containing agents, which are unstable and easily decompose, reducing bactericidal activity. Additionally, strong oxidants like sodium perborate and sodium percarbonate soaking can cause fabric fading, affecting their usage range.
According to domestic and international status and development trends, sterilization and energy-saving laundry technology will be the inevitable trend for the future development of the laundry industry. Qingdao Jieshen Laundry Co., Ltd. has developed sterilization and energy-saving laundry technology that uses ethylene oxide sterilizing gas to sterilize clothes before washing, cutting off the source of pathogenic contamination, preventing cross-contamination before and after washing, and eliminating bacterial transmission. This technology uses low-temperature gas fumigation, overcoming the various drawbacks of sterilization by ozone, ultraviolet light, and liquid detergents, and for the first time introduces "ethylene oxide disinfection and sterilization technology" into the laundry field, opening a new chapter of environmentally friendly, energy-saving disinfection and sterilization in the laundry industry. The technology performs well in disinfection and sterilization, water saving, and energy saving. From the sterilization perspective, ethylene oxide molecules can alkylate carboxyl (-COOH), amino (-NH2), sulfhydryl (-SH), and hydroxyl (-OH) groups on essential metabolic gene proteins inside cells, replacing unstable hydrogen atoms on these groups to form compounds containing hydroxyethyl groups (-CH2CH2OH). This compound disrupts essential reaction groups in microbial metabolism, affecting bacterial enzyme function and causing microbial death. Ethylene oxide has strong penetration ability and can effectively kill various bacterial vegetative cells, spores, viruses, and fungal spores without damaging clothes.
The greatest advantage of ethylene oxide is that it contains no chlorofluorocarbons or hydrochlorofluorocarbons, does not damage the atmospheric ozone layer, and the residual ethylene oxide after sterilization is discharged into water to form non-toxic ethylene glycol, causing no environmental pollution. Using ethylene oxide sterilizing gas to sterilize clothes before washing also reduces the use of large amounts of disinfectants, causing no environmental pollution and achieving sterilization and environmental protection in the first washing process. This is also the first international application of medical ethylene oxide sterilization technology in the laundry and dyeing industry. Staff classify and pack all dirty clothes collected at the store, then place them into a sealed ethylene oxide sterilizer for low-temperature fumigation. After four to six hours, the clothes are thoroughly sterilized. Additionally, ethylene oxide has extremely strong penetration and can penetrate micro-porous cotton and wool fibers without unpacking, thoroughly removing stains. Thorough sterilization before washing completely cuts off the source of bacterial contamination on clothes before washing. The washing and post-washing processes are sterile, truly achieving healthy and environmentally friendly laundry.
The water-saving technology of sterilization and energy-saving laundry technology uses recyclable water for washing clothes, reducing water loss and environmental pollution, and improving water utilization. First, a complete washing dragon production line was designed and established. This washing dragon classifies clothes into three compartments for pre-washing, using squeezed water from washed clothes (neutralized water after rinsing) as pre-wash water. After pre-washing, clothes undergo six-compartment main washing and three-compartment rinsing. Laundry wastewater is collected in a storage tank, where biological treatment agents and their optimal formula combinations chemically react to precipitate dissolved organic pollutants, heavy metal ions, and harmful salts as tiny particles with solid-phase interfaces, focusing on floc formation. Sand filtration and adsorption filtration remove remaining organics or chloroform and chlorophenol formed by organics reacting with chlorine, treating wastewater into reusable washing water (biologically treated return water after rinsing). This water is returned to the washing dragon's three-compartment pre-wash and six-compartment main wash, achieving water-saving and environmental protection in the second washing process. The entire washing dragon production line ensures good washing quality and extends fabric lifespan. It pioneered large-scale, industrialized, and specialized laundry and dyeing. Currently, laundry water usage is reduced by 80% compared to original usage, saving about 330,000 cubic meters of water annually, generating significant economic benefits.
The energy-saving technology of sterilization energy-saving laundry technology utilizes advanced photonic technology. It uses a solar selective absorption surface to increase the absorption rate of solar energy, and employs vacuum selective coatings and transparent heat insulation materials to reduce heat loss. Forced convection and fin technology are used to increase the heat transfer coefficient. By combining air heaters and water heaters to meet the heat demand of production, it dries and disinfects washed clothes, performs steam ironing, and fully automatic mannequin shaping, greatly reducing power consumption, saving about 320,000 kWh annually, improving economic efficiency, thereby making the third process of washing energy-saving and environmentally friendly.
This sterilization energy-saving laundry technology uses ethylene oxide combined with carbon dioxide to create a stable sterilizing gas for pre-wash sterilization of clothes, allowing washing under sterile conditions. Creatively, it integrates ethylene oxide sterilization, wastewater treatment recycling water, and solar energy technology for the laundry industry. Compared with similar technologies, it has advantages such as comprehensive and thorough disinfection, water and electricity saving, and completing the entire process automatically in one go. It not only improves internationally advanced laundry production lines but more importantly improves international advanced laundry industry management standards and service concepts.
China has a population of 1.3 billion, and the laundry industry's development prospects are broad, with huge market potential for modern washing in our country. With the improvement of living standards, people no longer only care about the cleanliness of clothes; they care more about washing quality. Using sterilization and environmentally friendly washing technology ensures washing quality while preventing cross-infection, effectively blocking bacterial transmission, preventing environmental pollution, and greatly reducing laundry costs. This technology is environmentally friendly and reliable, has good industrialization prospects, large market demand, and has an immeasurable driving effect on the development of the entire washing industry and society. With the continuous development of washing technology, China's laundry industry will surely usher in a new spring.
 
References:
[1] Zhou Mi, Xue Bingzhong, Zhang Fan. Disinfection effect, influencing factors, and decomposition kinetics of ozone [J]. Shanghai Preventive Medicine, 1998, 10(8): 350-352.
[2] Huang Jingxiong. Ethylene oxide sterilization [J]. Chinese Journal of Hospital Infection, 2004, 14(12): 1435-1439.
[3] Huang Jingxiong. Research on low-temperature sterilization [J]. Chinese Journal of Hospital Infection, 2002, 12(8): 601-603.
 
 
 
Author:
Qingdao Jieshen Laundry Co., Ltd. Shandong Qingdao 266033 Sun Shanjia
Qingdao Center for Disease Control and Prevention, Shandong, Qingdao, 266033 Cui Ying