A new study has shown that a disinfection solution used by a popular tank cleaning company may contain legionella bacteria, a dangerous waste product that can cause serious health concerns. This worrying discovery was made when members of the public took a sample of bacteria from their water in a nearby sink in Southampton Hampshire. The researchers then performed a sample analysis to identify what the contaminant was. This research was undertaken as part of an environmental health and safety survey that also involved samples taken from the town's wastewater pipe network.
The risks assessment report concluded that the concentrations of legionella found in the samples was a worrying level, with nearly nine hundred times more bacteria than was considered safe for human consumption. It is the highest level recorded in the UK. The team believes that the high water flow rate at the main tank of the treatment plant might be responsible for the contamination. There is a possibility that the bacteria could have entered the sewage system from a breakdown of storm water drains near the Treatment Works. It is also thought that the contaminated water may have originated from a storm water drain inside the house or a storm water pipe near the home.
The tank cleaning firm in question is one of the most popular in the area, operating a number of treatment works including a marine waste treatment centre and a large water tank cleaning facility at the southern end of the county. Its regular clientele are the local residents who take advantage of the fresh water from the treatment plant. They include many children and elderly people who live in rented accommodation. One of the things that the firm does on a regular basis is a pre-treatment cleaning of the tanks and pipes at the wastewater treatment plant. One of the problems that the researchers discovered was that the sediments that had accumulated inside the pipes was blocking the flow of water into the tanks.
Once the sediment was removed, it was found that the water had been polluted with a large concentration of Vibrio vulgaris bacteria. The proportion of the bacteria was such that it was clearly visible to the naked eye. Once the water was filtered out and decanted back into the river, it was found that there was a significantly reduced biological concentration in the treated water. This is because as the sediment was removed, some of the naturally occurring contaminants were washed away. This may explain why there was a reduced biological concentration in the treated water.
There is also the potential connection between the use of ultraviolet light in decontamination and legionella. Ultraviolet light can kill bacteria by damaging their DNA. It is not known how this may have influenced the prevalence of legionella in the environment of Southampton. The scientists involved conducting laboratory tests but could not find a direct link between the two. They did conclude however, that more research is needed to strengthen the link between ultraviolet light and legionella.
The scientists involved carried out wastewater sample assessment in the same place where they carried out the legionella risk assessment. When they performed both tests, they managed to get nearly identical results. This means that the conclusion of each test is more likely to be accurate than a single sample can give. Therefore, if you are planning to install a wastewater treatment plant in your region you should consider both these tests to make sure your chosen facility can deal with the threat.
Total Water Compliance Ltd.
Cumberland House, Grosvenor Square
Southampton, Hampshire SO15 2BG
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