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PSEUDOMONAS

A PROBLEM FACING BUILDING SERVICES

Previously known as the London Problem pseudomonas bacteria is now being foundin heating and chilled water systems in many parts of the country. Until the last coupleof years bacteria in these types of systems were of little concern and not ofteninvestigated. Now pseudomonas has started to appear in mains water supplies, whereit has no significant health concerns, but can have a major effect on the water systemsin commercial buildings.

Corrosion and Blockages

Pseudomonas is a biofilm or slime-producing bacteria and left to proliferate can causesevere corrosion and blockages within pipework. This particularly affects modernbuildings with the small-bore pipework and small orifices associated with controlvalves. The biofilm can reduce the water flow and provide a habitat for other corrosioninducing bacteria that will lead to pitting and leaking pipework. The net result ofpseudomonas in heating and chilled water systems is a decrease in their efficiency andincrease down time and costs from repairing leaks.

Health Concerns

Most pseudomonas do not have any effects on human health, but one speciespseudomonas aeruginosaunder the right conditionscan cause infections. Its thereforedesirable to remove the pseudomonas to minimise risks to personnel such asmaintenance engineers who may come into contact with contaminated water.

Maintenance

Maintenance of heating and chilled water pipework involves the use of corrosioninhibitors added to the water. These are usually analysed on a quarterly basis by thewater treatment company. The most common types of corrosion inhibitors are those

based on nitrite. Phase Technology has found through its investigations that the ever-increasing problem associated with the inability to maintain a suitable nitrite level iscaused by the presence of pseudomonas bacteria. This is often in systems that havebeen in use for many years. We have found that the bacterium enters the pipework viathe mains, usually as a result of routine maintenance activities. The bacteria can thenutilise the nitrite as a food source, reducing its effectiveness as an inhibitor thereforefurther increasing the potential for pipework corrosion.

Eradication

It is essential that pseudomonas is eradicated from the heating and chilled water

systems. Moves are being made by the industry to improve the quality of water used tofill and flush new systems, such as avoiding using stagnant water and contaminated

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hoses, even the installation of UV radiation on their make-up. An important part of thepre-commission process has become the addition of a biocide to eliminatepseudomonas. Typically these have been the same biocides used by the watertreatment industry for many years and unfortunately have limited effectiveness against

pseudomonas and its biofilms.

Phase Technology has developed a process to eradicate pseudomonas using a uniqueproduct PHASECHEM 586. For two years PHASECHEM 586 has been undergoingtrials in a number of installations where pseudomonas has been a problem. Thesehave ranged from new build, to those that have been operational for many years, andsizes varying from 800 litres to 80,000 litres. In every case the approach taken byPhase Technology has been successful with systems remaining clear many monthsafter the treatment. Phase Technology has been asked on a number of occasions totreat systems where other more traditional biocides have failed, again thePHASECHEM 586 system proved effective.