- 10 August 2006 -

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Filter media: bacterial growth on filters - the silver solution

Bacterial growth can harm filters through unwanted layers of biofilm, the addition of unwanted tastes and odours, not to mention premature clogging. Jeffery Trogolo of AgION Technologies looks at how one filter manufacturer - Everpure - uses silver in its water filters to counteract these problems.

Food industry - current concerns

To address concerns over contamination, water suppliers treat drinking water with disinfectants such as chlorine, chloramines, ozone and chlorine dioxide. These chemical compounds work to kill potentially hazardous microbes such as bacteria, viruses, and parasites that travel through the water system. However, the addition of these chemicals can have a negative impact on the taste and odour of water. This can have a big impact in the food industry.

As a remedy for this situation, many consumers and commercial drinking water distributors such as restaurants, food service providers, and vending machine owners use filters to enhance the taste and odour quality of drinking water. Filters reduce impurities from the water and can also lower the levels of chemical treatments such as chlorine. Chemical reduction improves the taste and odour of water. However, after initial contact with a carbon medium, most chlorine has been removed, increasing the opportunity for bacterial growth.

What's the problem?

Bacterial growth can cause problems in filters by creating layers of biofilm and imparting unwanted tastes and odours or prematurely clogging filters. Biofilm is a thin layer of bacteria that forms on surfaces that are exposed to water. It develops when bacteria attach to a surface and begin to form a microcolony, which eventually develops into a coating. Biofilm can also have negative effects on the taste, odour and appearance of the water.

When biofilm begins to accumulate, it can clog the filter elements, slowing down the flow of water. This can result in the need to replace the filter prematurely. In the food service business, the unexpected clogging of a filter can mean an expensive service call or even operational problems at the restaurant as water flow decreases to a trickle.

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