- 10 August 2006 -

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Looking for a solution

Innovations in water filtration technology in recent years have improved the taste of water, while addressing the problem of bacteria growth inside the filter itself. Several companies have turned to naturally occurring antimicrobials, such as silver, which inhibits bacterial growth.

One company that uses silver-based technology in its water filters is Everpure, a supplier of water treatment systems to the foodservice industry. Everpure has consistently strived to provide its customers with the highest-quality product and services.

To remedy the problem of bacteria build-up and microbe growth in water filters and to address customer requests for filters with antimicrobial properties, Everpure turned to AgION Technologies, a manufacturer of a silver-based antimicrobial compound - that has been approved by the Environmental Protection Agency (EPA) for use in food processing facilities, and approved by the EPA and the Food and Drug Administration (FDA) for food contact surfaces. The compound has also received the approval of the European Food Safety Authority (EFSA), and has received the NSF Food Safety Leadership Award in the category of technology breakthrough.

Silver has been used for thousands of years as a safe and effective way to combat microbes. The ancient Egyptians used silver to line their water cisterns and, more recently, the United States National Aeronautics and Space Association (NASA) used silver in the 1960s to purify water on spacecrafts.

Other water filter providers have incorporated silver into their filtration devices in an effort to limit the growth of bacteria, enhance the quality of filtered water and lengthen the lifespan of the filter. Many use silverised granulated activated carbon filters, which provide antimicrobial protection but can impart a metallic taste on the filtered water. Because the silver-impregnated carbon is based on dissolving technology, it has an unreliable lifetime, often dissolving completely before the unit's filtration capabilities have run out. In addition, it typically releases high levels of silver in the first batch of water to pass through the filter, rendering it unfit for drinking.

AgION has developed a silver-based antimicrobial technology that can be safely and effectively incorporated into water filters. The compound is comprised of naturally occurring silver ions and a ceramic material called zeolite. The silver reversibly binds to the zeolite, which has a unique property of releasing silver when exposed to moisture, killing microbes that generally flourish in moist environments. Because silver release is equilibrium-controlled, not dissolution-controlled, it maintains a low and consistent level of silver for the lifetime of the filter.

This creates continuous, long-lasting protection from a broad range of micro-organisms, including bacteria, algae, and fungus. Compared with traditional filters, AgION protected filters' controlled release provides a dramatic stabilisation in silver levels. This process extends the longevity of protection, and prevents biofilm buildup for much longer than conventional antimicrobial treatments.

Everpure has incorporated the AgION antimicrobial compound into its line of Micro-Pure II filters. The Micro-Pure II technology is a proprietary blend of activated carbon treated with AgION's silver-based antimicrobial compound, which coats the unique pleated fibre membrane. The Micro-Pure II filters offer 40 times more filtering surface area than other systems of similar size. The filters are sold into the commercial food service, beverage and vending markets.

Test results

AgION-treated filters have been proven to have less microbial growth than untreated filters, and thus need to be replaced less frequently. AgION's internal studies of carbon filters treated with the antimicrobial, have shown a dramatic drop in bacteria growth. The effluent bacteria decreased by up to 99.9 percent, depending on water conditions and filter media.

Another study conducted by AgION found that over a six-week time period, untreated filters had over one thousand times the number of microbes - measured by CFU per mL - than comparable filters that had been treated with AgION.

Conclusion

Beneficial innovations in water filter technology increase filter performance and result in higher customer satisfaction.

In an industry where it can be hard for customers to distinguish between different filter products, innovations such as silver-based antimicrobial coatings help set certain filters apart, and give customers the reassurance that their filtered water is clean, good tasting and safe.

Jeffery Trogolo, PhD, is chief technology officer at AgION Technologies, Inc., developer of controlled release antimicrobial solutions for consumer, industrial and medical applications.

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