The U.S. Environmental Protection Agency’s (EPA) Water Infrastructure Resiliency and Finance Center, in collaboration with the...
In an increasingly regulated and safety-conscious market, the beverage industry has to keep up with stringent standards of quality. Microbial growth in beverages due to contaminated water supplies or sugar syrups can cause discoloration, off flavors and shortened shelf life, as well as an increased risk of infection for consumers. The threat of contamination is further increased as manufacturers respond to consumer demand for a reduction in chemical additives and preservatives. Effective microbial disinfection of the whole manufacturing process is therefore essential.
A non-chemical method of disinfection that is gaining increasing acceptance is ultraviolet (UV) disinfection. UV kills all known spoilage microorganisms, including bacteria, viruses, yeasts and molds (and their spores).
UV is the part of the electromagnetic spectrum between visible light and X-rays. The specific portion of the UV spectrum between 185 and 400 nm has a strong germicidal effect, with peak effectiveness at 265 nm. At these wavelengths, UV kills microorganisms by penetrating their cell membranes and damaging the DNA, making them unable to reproduce and effectively killing them. Virtually any liquid can be effectively treated with UV, including raw mains water, filtered process water, viscous sugar syrups, beverages and effluent.
There are two main types of UV technology based on the type of UV lamps used: low pressure (LP) and medium pressure (MP). LP lamps have a monochromatic UV output (limited to a single wavelength at 254 nm), whereas MP lamps have a polychromatic UV output (with an output between 185 and 400 nm).
UV disinfection has many advantages over alternative methods. Unlike chemical biocides, UV does not introduce toxins or residues into process water and does not alter the chemical composition, taste, odor or pH of the fluid being disinfected. This feature is especially important in the beverage industry, where the chemical dosing of incoming process water can cause off-flavors and alter the chemical properties of the product.
UV treatment can be used for primary water disinfection or as a back-up for other water purification methods, such as carbon filtration, reverse osmosis (RO) or pasteurization. Because UV has no residual effect, the best position for a treatment system is immediately prior to the point of use. This ensures that incoming microbiological contaminants are destroyed and there is a minimal chance of post-treatment contamination.
Direct contact water: Although municipal water supplies are normally free from harmful or pathogenic microorganisms, this should not be assumed. Any water used as an ingredient in 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 for the reuse of process water, saving money and improving productivity without risking the quality of the product.
Sugar syrups: Sugar syrups can be a prime breeding ground for microorganisms. Although syrups with a 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.
Clean-in-place rinse water: It is essential that the clean-in-place (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. Because of their mechanical strength, medium pressure (MP) lamps are not affected by any sudden changes in the temperature of the CIP water, such as when hot 176?F liquid is instantly followed by cold 50?F.
Filter disinfection: Stored RO and granular activated carbon (GAC) filtrate is often used to filter process water but can be a breeding ground for bacteria. UV is an effective way of disinfecting both stored RO and GAC-filtered water, and it has been used in the process industries for many years.
Dechlorination: GAC filters are also used to dechlorinate process water, removing the off flavors associated with chlorine disinfection, so that the flavor of the final product remains untainted and free from unwanted flavors or odors. Placing UV systems ahead of GAC filters used for dechlorination improves the performance of the filters and results in longer carbon runs, thus decreasing operating costs.
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, food spoilage organisms are eliminated, extending the shelf life of the product and reducing the risk of contamination.
Tank head space disinfection: UV systems can 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 airborne spores. To prevent this, immersible UV treatment systems have been designed to fit in the tank head air space and disinfect the air present.
Wastewater: Effluent from beverage manufacturing facilities can be treated without the use of environmentally hazardous chemicals. This ensures all discharges meet with local environmental regulations. As already mentioned, because process water can be treated and reused with UV, this also leads to a significant reduction in the amount of wastewater produced.
For those manufacturers seeking to improve the quality of the end product, MP UV is an economic, realistic option. It is already a well-established method of disinfecting drinking water throughout the world. It is also widely used for high-purity applications, such as pharmaceutical processing and brewing.
MP UV disinfection systems are easy to install, with minimum disruption to the plant. They need very little maintenance, the only requirement being replacement of the UV lamps every nine to 12 months, depending on use.