Turbidity monitors keep Thames Water in the clear

Turbidity monitoring equipment from ABB is helping Thames Water maintain the highest water purity standards at its new borehole extraction site.

Turbidity monitoring equipment from ABB is helping Thames Water maintain the highest water purity standards at its new borehole extraction site.

The borehole, at Bell Green in Lewisham, South London, has a peak extraction potential of 17.3Mlitre/d.

Thames Water sets stringent standards for the turbidity of drinking water of 0.1 NTU (Nephelometric turbidity units - the unit of measurement for turbidity), stricter than the levels set by the Drinking Water Inspectorate.

To achieve this standard at Bell Green, Thames Water worked with water industry specialists Purac to install ten pressure filters for the new borehole.

As part of its framework agreement with Thames Water, ABB supplied 10 AnalyzeIT 4670 series turbidity analysers to monitor the quality of water from the filters.

Designed specifically for monitoring final-treated potable water and filtered water where accurate results below 0.1 NTU are demanded, ABB's 4670 turbidity analysers incorporate sensors which use the 90-degree scattered light principle to measure the concentration of waterborne particulate matter.

As well as helping Thames Water to maintain its high water quality standards, the analysers also bring other benefits.

Alan Barton, Thames Water's Project Engineer on the Bell Green project, says: "By accurately monitoring the level of particulate matter in the water, ABB's turbidity analysers can help us predict when the filters need to be washed out".

"This helps us ensure we wash the filters only when we need to, so reducing maintenance time and replacement costs".

Also supplied as part of the installation were 11 ABB FieldIT MagMaster electromagnetic flowmeters.

These were also installed on the filter outlets to measure the balance across the filters and ensure that each filter is supplied with the correct amount of water.

"All ABB's water quality equipment is simple to use".

"The MagMaster flow meter is also a superb product to work with and very easy to install", says Steve Cole, Project Manager for Purac.

"Thames specified the ABB equipment but it is standard practice at Purac to use ABB whenever possible".

"Reliability and cost-effectiveness are the vital criteria we are looking for in water quality monitoring and using ABB's water analysis products enables us to deliver these benefits to our clients".

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