Applications For UV Disinfection Technology In The Beverage, Bottled Water And Food Processing Industries
Ultraviolet (UV) technology was originally used in Europe as an alternative to chlorination to ensure the adequate disinfection of municipal drinking water supplies. It is now applied globally for the disinfection of drinking water, wastewater, process water and industrial affluent. It is also used for non-disinfection applications such as dechlorination in many process industries.
UV technology is particularly suited to the beverage, bottled water and food processing sectors, where extremely high standard of hygiene are expected. Contamination of the process at any point by pathogenic or spoilage microorganisms can have extremely serious consequences for manufacturers. Effective microbial disinfection of the whole process is therefore essential.
UV is rapidly gaining acceptance across the whole spectrum of food and beverage industries as a highly efficient, non-chemical method of disinfection. UV kills all known pathogenic and food spoilage microorganisms, including bacteria (including Cryptosporidium and Giardia) viruses, yeasts and molds (and their spores). It is a low maintenance, environmentally friendly technology which eliminates the need for chemical treatment while ensuring very high levels of disinfection.
UV disinfection 101
UV is the part of the electromagnetic spectrum between visible light and X-rays. The specific portion of the UV spectrum between 185-400nm (also known as UV-C) has a strong germicidal effect, with peak effectiveness at 265nm. At these wavelengths UV kills microorganisms by penetrating their cell membranes and damaging the DNA, making them unable to reproduce and effectively killing them.
A typical UV disinfection system consists of a UV lamp housed in a protective quartz sleeve which is mounted within a cylindrical stainless steel chamber. The fluid to be treated enters at one end and passes along the entire length of the chamber before exiting at the other end. Virtually any liquid can be effectively treated with UV, including spring, surface or municipal water, filtered process water, viscous sugar syrups and industrial effluent.
There are two main types of UV technology, based on the type of UV lamps used: low pressure and medium pressure. Low pressure lamps have a monochromatic UV output (limited to a single wavelength at 254nm), whereas medium pressure lamps have a polychromatic UV output (with an output between 185-400nm). Low pressure systems are usually best suited for small, intermittent flow applications, while medium pressure technology is better suited to higher flow rates.
Benefits of UV disinfection
UV disinfection has many advantages over alternative methods. Unlike chemical biocides, UV does not introduce toxins or residues into the process (which themselves have to be subsequently removed) and does not alter the chemical composition, taste, odor or pH of the product.
UV treatment can be used for primary disinfection or as a back-up for other treatment methods such as carbon filtration, reverse osmosis or pasteurization. As UV has no residual effect, the best position for a treatment system is immediately prior to the point of use. This ensures incoming microbiological contaminants are destroyed and there is a minimal chance of post-treatment contamination.
Installing UV systems
UV systems can be installed at various points along a process system, with minimum disruption to the plant. Installation or retrofitting to existing pipework and vessels is relatively straightforward, requiring minimum disruption and site preparation. Depending on the level of use, the only routine maintenance required is replacing the UV lamps every 12 months, depending on lamp type and use. Lamp replacement is a simple operation that takes only a few minutes and can be carried out by general maintenance staff.
UV applications in industry
Direct contact water
Although municipal water supplies are normally free from harmful or pathogenic microorganisms, this should not be assumed. In addition, water from private sources such as natural springs or wells could also be contaminated. Any water used either as an ingredient in food or beverage products, or coming in direct contact with the product, can therefore be a source of contamination. UV disinfects this water without chemicals or pasteurization. It also allows the re-use of process water, saving money and improving productivity without risking the quality of the product.
CIP (Clean-in-Place) rinse water
It is essential that the CIP final rinse water used to flush out foreign matter and disinfecting solutions is microbiologically safe. Fully automated UV disinfection systems can be integrated with CIP rinse cycles to ensure final rinse water does not reintroduce microbiological contaminants. Medium pressure lamps are ideal for this application because of their mechanical strength, meaning they are not affected by any sudden changes in the temperature of the CIP water, such as when hot (80oC) liquid is instantly followed by cold (10oC).
Using UV to disinfect the water used to rinse or wash process equipment and work surfaces can dramatically decrease contamination, increasing shelf life. UV also reduces the amount of chlorine needed to disinfect rinse and wash water.
Stored reverse osmosis (RO) and granular activated carbon (GAC) filtrate is often used to filter water, but can be a breeding ground for bacteria. Installing UV systems post-filter is a highly effective way of disinfecting both stored RO and GAC filtered water.
GAC filters are also sometimes used to dechlorinate water following chlorine treatment. Dechlorination removes the ‘off’ flavors often associated with chlorine disinfection, meaning the flavor of the final product remains untainted and free from unwanted flavors or odors. Placing UV systems ahead of GAC filters improves the performance of the filters and results in longer carbon runs, so decreasing operating costs.
Sugar syrups used as flavorings in the beverage, fruit juice and bottled water industries can be a prime breeding ground for microorganisms. Although syrups with a very high sugar content do not support microbial growth, any dormant spores may become active after the syrup has been diluted. Treating the syrup and dilution water with UV prior to use will ensure any dormant microorganisms are deactivated.
Packaging & surface disinfection
Surface disinfection systems are used to reduce microbial counts on all kinds of packaging, including glass and plastic bottles, cans, lids and foils. By irradiating the surfaces with UV prior to filling, spoilage organisms are eliminated, extending the shelf life of the product and reducing the risk of contamination.
Air disinfection in ductwork and storage tank head spaces
Special UV air disinfection systems are available to treat air in the ductwork of air conditioning systems serving cleanrooms and other high purity areas. Air treatment systems can also be used to disinfect displacement air for pressuring tanks or pipelines holding perishable fluids. Storage tanks are particularly susceptible to bacterial colonization and contamination by air-borne spores. To prevent this, immersible UV treatment systems have been designed to fit in the tank head air space and disinfect the air present.
UV systems can be used in conjunction with other waste treatment processes to disinfect wastewater without chemicals, making it fit to use again or fit to discharge into watercourses. By using this low-maintenance technology, plant production capacity can be increased and hazardous chemicals are eliminated.
While reusing wastewater means a dramatic reduction in discharges to watercourses, any effluent that does have to be discharged can also be disinfected with UV to meet with local environmental regulations.
Meeting the increasingly rigorous hygiene standards required in the beverage, bottled water and food processing industries is becoming more of a challenge, particularly as more consumers are demanding a product that has not been treated with chemicals. If improvements need to be made to plant and equipment, they need to bring quick returns on the investment and measurable improvements in product quality.
UV is already a well established disinfection method in high purity applications such as pharmaceutical manufacturing, where water of the highest quality is required an economic, and is an ideal solution for those operators seeking to improve the quality of their product.