By Jon McClean

Abstract
Effective microbial disinfection in the bottled water industry is essential. Ultraviolet (UV) disinfection is gaining increasing acceptance as a versatile treatment method. UV destroys the DNA of microorganisms and reduces the need for chemical treatment. It can be used to disinfect incoming water, sugar syrups, clean-in-place water, wastewater, filter systems and the surfaces of packaging. UV systems are easy to install and maintain.

Introduction
In an increasingly regulated and safety-conscious market, the bottled water industry has to meet ever-higher standards of quality. Contamination of incoming water supplies, be they from spring, well, surface or municipal sources, with Cryptosporidium, Giardia, E.coli or other pathogenic or spoilage microorganisms can have serious consequences, for producers. If contamination is detected early enough, then at least the contaminated batch can be rejected and destroyed, (with obvious cost impacts for the producer). Far worse if a contaminated batch is not identified; the legal, financial and health implications of consumers becoming infected does not bear thinking about. The threat of contamination is also higher now than ever before, as producers respond to consumer demands for a reduction in chemical treatment. Effective microbial disinfection of the whole process – from source to final bottling – is therefore essential.

A non-chemical method of disinfection rapidly gaining acceptance across the whole spectrum of food and beverage industries is UV disinfection. UV kills all known spoilage microorganisms, including bacteria, viruses, yeasts and molds (and their spores). It is a low maintenance, environmentally friendly technology that eliminates the need for chemical treatment while ensuring very high levels of disinfection.

How UV disinfection works
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 mounted within a cylindrical stainless steel chamber. The water 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 wastewater 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). Generally speaking, low pressure systems are best suited for small, intermittent flow applications, while medium pressure technology is better suited to higher flow rates. (*Monochromatic pertains to radiation of a single wavelength{or a narrow range of wavelengths}; polychromatic is radiation of more than one wavelength.)

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 water.

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 or pasteurization. As UV has no residual effect, the best position for a treatment system is immediately prior to the point of use (POU). This ensures that incoming microbiological contaminants are destroyed (inactivated) and there is a minimal chance of post-treatment contamination.

UV applications in the bottled industry
Incoming water supplies

Although natural springs and municipal water supplies are normally free from harmful or pathogenic microorganisms, this should not be assumed. Surface water from wells, rivers or lakes can be contaminated and should be disinfected.

Sugar syrups
Sugar syrups used as flavorings 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 that dormant microorganisms are deactivated.

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).

Filter disinfection
Stored water from reverse osmosis (RO) and granular activated carbon (GAC) filters is often used but can become stagnant and serve as a breeding ground for bacteria. UV is an effective way of disinfecting both stored RO and GAC filtered water and has been used in the process industries for many years.

Dechlorination
GAC filters are sometimes used to dechlorinate water following chlorine treatment. Dechlorination removes the ‘off’ flavors often associated with chlorine disinfection, meaning 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, so decreasing operating costs. HOW MUCH OF THE CHLORINE IS REMOVED IF THESE ARE IN SERIES?

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.

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 air-borne spores. To prevent this, immersible UV treatment systems have been adapted to fit in the tank head air space and disinfect the air present.

Wastewater
UV allows effluent from processing facilities to be treated without the use of environmentally hazardous chemicals. This ensures that all discharges meet local environmental regulations. As already mentioned, because process water can be treated and re-used with UV, this also leads to a significant reduction in the amount of wastewater produced.

Conclusion
Meeting the increasingly rigorous hygiene standards required in the production of bottled water 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 must bring quick returns on investment and measurable improvements in product quality.

For those producers seeking to improve the quality of the end product, 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 semiconductor manufacturing, where water of the highest quality is required.

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 12 months, depending on use. This is a simple operation that takes only a few minutes and can be carried out by general maintenance staff.

About the author
Jon McClean is President of Aquionics Inc. in the US and is also Divisional Managing Director of the Halma UV Companies, which include Berson UV-techniek in the Netherlands and Hanovia Limited in Great Britain.

He was appointed President of Aquionics in 2005; before that he was Managing Director of Hanovia. During his six years with Hanovia, McClean developed new markets for the company’s UV disinfection and de-chloramination technology in the pool and drinking water sectors. He also won the Queens Award for Enterprise, Britain’s most prestigious award for business performance.

McClean has over 20 years of experience in the water industry, ranging from municipal and water reuse applications to specialized ultra pure industrial uses. He holds an MBA and a B.Sc. in Physics from Imperial College in London (Great Britain). Reach him at Aquionics Inc., 21 Kenton Lands Road, Erlanger, KY 41018 USA; telephone: +1 859 341 0710; Fax: +1 859 341 0350 or via email: jon.mcclean@aquionics.com. Visit the company’s website, www.aquionics.com

About the company
Aquionics Inc. is a market leader in the manufacture, application and development of UV technology for progressive, non-chemical disinfection and microbiological control. The company’s systems are used in a wide variety of applications including municipal water and wastewater treatment, pharmaceutical and electronics manufacturing, food and beverage processing and brewing.

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