Monitors keep check on nitrates

An ABB Automation Tech (Instrumentation + Automation) product story

Edited by the Engineeringtalk editorial team Apr 12, 2004

Nitrate monitoring equipment from ABB is being used by Wessex Water to regulate the level of nitrates in drinking water to ensure that all water into supply remains within the prescribed standard.

Nitrate monitoring equipment from ABB is being used by Wessex Water to monitor and regulate the level of nitrates in drinking water to ensure that all water into supply remains within the prescribed standard.

15 AnalyzeIT 7330 UV nitrate monitors have been installed at various sites in Dorset, Somerset and Wiltshire.

The Water Supply (Water Quality) Regulations 2000 impose a limit of 11.3mg/l as N (50mg/l as NO3) on the level of nitrate in drinking water.

If left untreated, excessive nitrate levels can result in "blue baby syndrome" a rare blood condition that can affect young babies.

Although nitrate levels in drinking water supplied by Wessex Water are well below the UK and EU limits, levels are increasing at a number of underground water source sites.

This is due to leaching of nitrates from agricultural land during winter and spring when rainfall is refilling the underground storage aquifers.

ABB's UV nitrate monitors are being used to provide continuous online measurement of the nitrate levels in the raw water from the aquifiers.

Depending on the level of nitrates present, the source may be either temporarily taken out of service until the nitrate level decreases, blended with a low nitrate source or treated.

On sites where treatment or blending is employed, ABB's monitors are used to determine the level of treatment required and the blend ratios.

As well as monitoring and controlling the treatment process, ABB's monitors are also being used by Wessex Water to collect data on nitrate levels at the sites.

"By using the monitors to collect data, we can explore correlations with rainfall and groundwater levels to better predict future nitrate pollution", says Andy Purvey, Supply Planner, Wessex Water.

"We can also use this information to help us to design more effective and efficient treatment processes".

The ABB UV nitrate analyser features two programmable alarms as standard, which are used by Wessex Water to help provide early warning of any potential problems.

The ABB Series 7330 nitrate analyser is a straight-through system requiring no consumable reagents or pump tubes, which can be simply calibrated and commissioned.

Designed for use on potable water treatment plants, it includes advanced features such as automatic online diagnostics for maintaining measurement integrity and automatic compensation for turbidity and organics which eliminates the need for expensive, maintenance-prone sample filtration facilities.

The analyser also incorporates an automatic optical cleaning facility, minimising the need for manual intervention.

"Wessex Water continues to supply high quality drinking water to all of its customers", says Purvey, "As part of this process ABB's nitrate monitors make a significant contribution to ensuring these high standards are maintained".