UV disinfection techniques can be used to treat air, water and surfaces
By Robert McIlvaine and Karen Vacura, The McIlvaine Company
Cleanrooms in hospitals, food processing, pharmaceuticals, medical devices, biotechnology, and animal research are all concerned with biological contaminants and therefore are candidates for ultraviolet irradiation to treat air, water and surfaces. The technology can also be used in the semiconductor industry to treat water for dechlorination and removal of total organic compounds (TOC).
Germicidal UV is delivered by a mercury-vapor lamp that emits UV at the germicidal wavelength, known as UV-C or shortwave UV, which ranges from 200 to 280 nm with 254 nm being the ideal wavelength for eradicating pathogens. Many bulbs use special transformers to ensure even electrical flow to the bulbs to maintain the correct wavelength. The three basic groups of biological contaminants-mold/fungi, bacteria and viruses-are all susceptible to UV energy. The dose of UV needed to affect each group varies, however. Viruses are the easiest to sterilize, followed by bacteria. Mold and fungi are the hardest to eliminate and require very long exposure times.
Air disinfection techniques include:
- upper room disinfection systems, which create beams of UV rays parallel to the ceiling that are confined to the upper portion of a room volume. Air that gravitates into this field is disinfected.
- in-duct UVGI systems, which serve the purpose of disinfecting an airstream in a building or room ventilation system. Such systems often serve a dual purpose, disinfecting either internal air handling unit surfaces or cooling coils, depending on their location and arrangement.
- lower room UVGI systems, which create a UV field in the lower 1 to 2 feet of floor space much the same as upper room systems for ceilings. Though rare, such systems have been and could be used in operating rooms and other facilities where the predominant problem is airborne microbes, like spores or bacteria, that tend to settle downward.
- portable forced-air recirculation equipment using both UVGI and HEPA filtration.
Many UVGI systems are coupled with a filter. The filter not only protects the UV lamps from dust but also forms an integral part of the air disinfection capabilities. The filters will tend to remove larger microbes, such as fungal spores, that may be resistant to UV.1
In the residential and commercial sectors, surface microbial growth control accounts for about a third of total UVGI systems applications, based on manufacturers’ estimates. In-duct applications and upper air units each have about a quarter of the market; and portable units for room recirculation make up the remainder. Most of the systems are being installed in healthcare facilities, followed by homeless shelters and prisons, which use upper air systems.2
The use of systems for disinfecting air and controlling microbial growth is growing in the United Sates and Europe, according to manufacturers. In third-world countries, however, demand for upper air disinfection systems is high because of the TB pandemic, strained economics and the common use of natural ventilation.3
Biopharmaceutical manufacturers are evaluating UV as a supplement to HEPA filters in filtering critical environments and reducing ductwork sanitization. UV installed in a cleanroom HVAC system can act as a secondary barrier against introduction of bioburden into ducts, onto filters and into the cleanroom.4
The major bulb manufacturers include Philips Lighting, First Light, Osram Sylvania and Light Sources. Some smaller Chinese companies have entered the market, but the quality is unknown.
Philips offers five ranges of lamps for disinfection purposes. All are based on low-pressure mercury technology. Increasing the lamp current of low-pressure lamps produces higher outputs for lamps of the same length. The application of mercury amalgams rather than pure mercury in the lamps maintains the UV efficiency when faced with higher self-absorption levels and temperature influences.5
First Light manufactures both low- (185 and 254 nm wavelengths) and medium-pressure UVC lamps. Besides producing 254 nm wavelengths of ultraviolet, some germicidal lamps are designed to produce controlled amounts of a shorter wavelength of ultraviolet measured at 1,850 angstrom units (commonly referred to as 185 nm). This wavelength has the power of generating ozone, which is a form of oxygen that is an extremely effective germicidal agent. Ozone also has the power of oxidizing odor molecules and therefore acts as a deodorizer. A further advantage is that ozone can be carried by air into places that the UV rays cannot reach directly. Ozone-producing lamps are commonly used for pool and spa water treatment, TOC reduction and air purification.
Air purification systems manufacturer Lumalier (Memphis, TN) offers a complete selection of UVGI fixtures for upper room air and total building (in-duct) air disinfection. Lumalier’s president, Chuck Dunn, estimates the current total U.S. market for UVGI air purification at $30 million. The company’s products are used in the healthcare, educational, institutional, residential and commercial markets. Additionally, Lumalier works with government-funded programs and Partners in Health, a Boston-based non-profit organization that aims to bring western medicine to poor countries, to effectively eradicate TB and other pathogens in third-world prisons, hospitals and shelters.
Roger Stamper, vice president of Steril-Aire (Burbank, CA), sees tremendous growth in UVGI air applications. He estimates the current market at $50 million to $75 million worldwide, with most of it in the United States. Steril-Aire manufactures UVGI units in varying sizes, from very large units for airstreams to handheld units for surface disinfection.
Stamper expects the market will double in the next two years and could reach $0.5 billion in five years. He predicts U.S. commercial buildings and hospitals to be the highest growth areas. Additionally, there is interest in the Far and Middle East due to increasing hygiene standards and cost efficiency. Also, according to Stamper, hospital studies currently underway are expected to show a significant reduction in hospital-acquired infections (HAI) due to UVGI air applications.
Ultraviolet Devices, Inc. (UVDI; Valencia, CA) has 90 percent of its business in commercial HVAC applications. UVDI’s Larry Randall says the primary market is in the U.S., but estimates that the worldwide market is at least $50 million. He states the current growth rate is 15 to 20 percent per year and says the market has a huge potential to grow much larger. The company sees applications in schools as a growing area.
Triatomic Environmental (Jupiter, FL), manufacturer of the Fresh-Aire system, has a background in water and cleanroom disinfection and has now entered the air application market. Vice president Ron Saunders explains the company’s new product available for homeowners, the Fresh-Aire UV-filter system, which allows for a UV light and 1-inch filter to be combined for installation into any standard 1-inch filter slot. This approach provides not only filter and air sterilization but also allows the UV light to target hard-to-reach areas downstream of the filter element. The filter media is designed to increase the ability of the UV light to react with the moving airstream, increasing its reactivity with captured particulate to reduce airborne pathogens.
Saunders believes the market for residential indoor air in the U.S. is growing at a double-digit rate annually. Canada also has a large part of the market. The commercial market is also growing, but at a slower pace. For that market to grow, training is needed for facility managers on the cost-effectiveness of UVGI technology. He estimates the total market to be around $100 million.
Sanuvox Technologies (Quebec, Canada) offers units for residential and commercial applications, hospitals, casino smoking rooms, and also stand-alone portable units. Residential in-duct HVAC applications comprise a majority of its business. Aaron Engel, vice president, estimates a $70 million market for the entire in-duct and stand-alone UVGI air applications industry. Engel concurs that with more consumer education regarding UVGI in-duct applications, the market will continue to grow.
Currently there are no consensus standards for the design, application or testing of UVGI systems, but several agencies are investigating the development of guidelines. The International Ultraviolet Association (IUVA) UV Air Treatment Group has developed a set of draft Standards and Guidelines for UV Air Treatment Systems, which is being circulated for public discussion. These documents can be downloaded at http://www.iuva.org/public/Documents/IUVAG01A-2005.pdf.
The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) is working on testing standards for UV, with completion expected in 2 to 3 years, to provide mechanical and electrical engineer specifications for different applications. Additionally, the U.S. National Institute of Occupational Safety and Health (NIOSH) and the American Refrigeration Institute (ARI) are looking at UVGI applications. Such documents will ultimately provide a basis for the development of consensus standards that will support the rapid adoption and advancement of UVGI technology.
University and hospital studies, in addition to the development of guidelines, will increase facility manager and public knowledge of indoor air quality issues and cost efficiency. An increase in residential, school and commercial building applications is expected.
Forecasts for air treatment using UV include all applications. Since less than 10 percent of these applications are in cleanrooms, we have not segmented this market further.
Growth in the Americas and Europe is anticipated to be eight percent per year, while growth in Asia is anticipated to be 12 percent. The total market will grow from $80 million this year to $120 million in 2012 (see Table 1).
Cleanroom operators use UV not only in the pretreatment process for intake water but also for treatment of wafer rinse water, dechlorination and other special uses.
Table 1: UV air purification market ($ millions)
Major soft drinks groups use UV disinfection to provide microbiologically pure water and ingredients, which help protect the flavor and shelf life of their products. Soft drinks and bottled water producers build their reputations around the purity of their products, emphasizing the fact that they’re natural. UV is the only effective method of treating bottled water without compromising marketing assets.
Minute contaminants in rinse water, including microorganisms and total organic compounds (TOC), can adversely affect yields and must be removed by the water purification system. In order to meet these demands, UV technology for disinfection and organics removal is often used in the water treatment scheme. UV offers protection without the use of chemicals, and with recent developments in high-energy UV technology, higher quality standards are now achievable in a more simplified, efficient and cost-effective manner.
Table 2: UV water purification market-Electronics industry ($ millions)
Bacteria control is critical in areas of microbial proliferation such as carbon filters, deionized (DI) resins and storage tanks. Additionally, UV can be used to reduce biofouling of reverse osmosis (RO) membranes and minimize biofilm growth within the distribution system.
Table 3: UV water purification market-Food and beverage industry ($ millions)
TOC reduction is achieved with special photochemical UV lamps that can break down low-level organics by dissociation of molecular bonds and through photochemical oxidation. Some organics are also “conditioned” for subsequent removal in the DI resins.
Table 4: UV water purification market-Pharmaceutical industry ($ millions)
Deozonation is accomplished by cleaving triatomic oxygen molecules with ultraviolet rays, which converts ozone to oxygen. UV is commonly used to remove residual ozone used for sanitation purposes to protect downstream equipment from ozone attack. Additionally, the use of ozone followed by UV is often utilized to enhance organics removal in primary treatment steps or in reclaim water systems.
Dechlorination is achieved with special high-energy UV lamps to protect chlorine-sensitive RO membranes. Low-level free chlorine is destroyed at specific wavelengths in the medium-pressure UV lamp spectrum. UV can replace chemical dechlorination or activated carbon filter removal steps upstream of the RO equipment.
Four leaders in the electronics sector are Aquionics, Aquafine, Wedeco and Photoscience.
The water segment is dominated by the municipal wastewater and drinking water applications. However, the worldwide industrial sector accounts for sales of $125 million. Two thirds of this market is in industries with cleanrooms.
The market for UV in the semiconductor industry is currently $47 million, forecasted to reach $71 million by 2012 (see Table 2).
The food and beverage market will reach $24 million by 2012 (see Table 3).
Water purification using UV in the pharmaceutical industry is currently about $13 million, and is expected to grow to $18 million in 2012 (see Table 4).
Robert McIlvaine is president and founder of The McIlvaine Company in Northfield, IL. The company first published Cleanrooms: World Markets in 1984 and has since continued to publish market and technical information for the cleanroom industry. He can be reached at [email protected]
Karen Vacura is the air filtration market editor for The McIlvaine Company. She can be reached at [email protected]
- International Ultraviolet Association (IUVA), Draft Guideline: IUVA-G01A-2005 General Guideline for UVGI Air and Surface Disinfection Systems.
- Kowalski, W.J., and William Bahnfleth, “UVGI Design Basics for Air and Surface Disinfection,” HPAC Engineering, January 2000.
- Speer, Samuel E., and Rao S. Chatty. “Designing in Ultraviolet Technologies for Bioburden Reduction,” CleanRooms Magazine, June 2003.
- Philips UV Purification Brochure, January 2006.