Biofilm - Disinfecting using Hydrogen Peroxide Silver Biocides

Biofilm - This short paper examines the use of Accepta 8101, a highly effective disinfecting biocide formulated from hydrogen peroxide and silver, for the removal of biofilm. Biofilm are bacterial communities that can appear almost anywhere, fouling machinery, clogging pipes, and contributing to many forms of human disease.

Scientists and researchers have found that biofilm plays an important role in many medical conditions such as kidney stones, chronic ear and urinary tract infections and gum disease. Experts at the Centre for Disease Control (CDC) in Atlanta, USA now believe that biofilm are involved in 65% of all human bacterial infections. And, roughly 5% of patients who annually receive catheters and stents go on to develop serious infections from biofilms growing on these devices. Biofilm can also be found in water filters, on the hulls of boats and in drinking water pipes, where they can do great harm.

Worldwide, industry spends about $7bn on toxic chemicals that are only partially successful in blocking this bacterial scum.

At the earliest stages, this strange thing called a biofilm is little more than a layer of cells attached to a surface. But as the bacteria grow and divide, something wondrously conspiratorial happens. When enough of them - a quorum - have gathered, they send signals around, telling each other to reorganize. They begin to arrange themselves into an array of pillars and mushroom shaped structures, all connected by convoluted channels that deliver food and remove waste. They become in effect a community, with its own defence and communication systems. As the biofilm matures, the bacteria become as much as 1,000 times more resistant to antibiotics and biocides than they were when they were separate. So once a biofilm takes hold, getting rid of it is tough, though not impossible.

Traditionally, it has been believed that dosing water services and supplies with a conventional biocide such as chlorine will keep it free of harmful and possibly life threatening bacteria and viruses. Unfortunately, this is simply not true!

Bacteria can penetrate systems in several ways, these bacteria, once inside the system are not easily dislodged. The bacteria then gravitate towards the surfaces of the water tanks and pipes, where nutrient levels of adsorbed organic molecules are at their richest. Owing to their small size, the bacteria could very easily be swept away in the water flowing through the system. To prevent this happening, they secrete a polysaccharide glue like substance that fixes them to the surfaces and enables them to pick out nutrients carried along in the water. This polysaccharide matrix is what makes up the biofilm - surrounding each bacterium in layers of slime and creating a miniature "static pond" for it, safe from disruptive water currents.

The biofilm also acts as a barrier to biocides like chlorine, which react with its surface layers while letting the protected bacteria population grow unchecked, until they break out of the biofilm to cause disease and infection, such as an outbreak of Legionnaires disease. Fortunately, there is an answer to the problem created by biofilm. That answer is Accepta 8101.

"Solutions of Accepta 8101 will penetrate biofilm and destroy the bacteria on contact"

The necessity of using powerful biocides for biofilm removal is illustrated in recent work, which demonstrated that it took four times as much Bromide to destroy bacteria in biofilm as it took to destroy bacteria in water flow. Accepta 8101 can reduce bacteria levels to single figures, and more particularly it is very effective against Legionella, which can exist in systems even when the TVC water condition is well within accepted standards.

Its effectiveness against Legionella in both hot and cold systems will enable a building facility manager to provide safe water, even in systems which have difficulty in maintaining the 60°C level recommended. Dosing the system with Accepta 8101 can also prevent pipe corrosion caused by the co-existence of two quite different types of bacteria in the biofilm. The upper layers of bio-film are populated by aerobic bacteria, and the lower layers (lacking in oxygen) by anaerobic bacteria. This co-existence creates corrosion potential between the oxidising and reducing bacteria, resulting in the removal of pipe metal by natural electrolysis. Bio-film develops faster in plastic pipes than in metal pipes, as the bio-film will find nutrients in the organic content of the pipe.

Apart from its effectiveness in penetrating bio-film and killing the actual bacteria, solutions have a long residual level of disinfection. It is also less reactive than other biocides such as Chlorine or Ozone, which stay in the water for a significantly shorter period of time. By using solutions of Accepta 8101, protective levels of biocide can be maintained in water systems for 14 days or more and so provide protection during "Shut downs". The need to flush out systems or carry out Chlorinations prior to reopening can be eliminated.

Additional Information & Technical Support

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