Control of the clarification processes associated with the removal of natural organic matter remains one of the main challenges currently facing water utilities around the world. This is especially true when changes in source water, weather events or equipment issues result in a need for rapid action to maintain stable floc formation and reduce any potential impact on downstream processing.
Severn Trent Water, a leading UK supplier of water and waste water treatment services, has introduced the new Zetasizer WT, an innovative online zeta potential analyzer, to reduce operational risk and coagulant costs, at Tittesworth water treatment works (WTW). Severn Trent has conducted the UK’s first trials which have successfully demonstrated the ability of online zeta potential measurements to provide reliable, continuous and fully automated clarification monitoring. Plans are now in place to extend application of the technology to other WTWs across the Severn Trent Water group.
The Zetasizer WT is a standalone, fully automated analyzer that continuously monitors the charge of contaminant particles in water during coagulation to provide precise and reliable data for optimizing chemical dosage levels. The associated optimization of charge neutralization processes results in substantial financial benefits due to a reduction in chemicals usage. The new system delivers highly sensitive analysis, via continuous monitoring with associated alarms, which enables a proactive response to changes in the process, resulting in minimal manual input whilst enhancing plant stability and reducing the risk of significant events from rapid naturally occurring changes in raw water quality.
Emma Sharp, Water Treatment and Quality Lead at Severn Trent Water, comments, “We’ve been investigating the ability of zeta potential measurements to enhance water treatment control for close to a decade at Severn Trent now. The successful outcome of recent trials at Tittesworth has confirmed that online analysis provides a far more robust platform for effective process control, than traditional techniques such as jar tests. The installation of Malvern’s Zetasizer WT has been extremely beneficial in providing numerous improvements over lab based measurement in terms of rapid, real time data acquisition, while at the same time reducing reliance on manual analysis.”
“At Tittesworth this technique has now been adopted as our lead measure of clarification performance, as online zeta potential has securely established its ability to enhance coagulation control. Additionally, the data provided by the Zetasizer WT can be easily interpreted and responded to with appropriate action, providing a robust platform for effficient process control. We are now looking to roll the technology out to other sites with comparable source water quality/properties.”
The value of zeta potential measurement is further underlined by successful evaluation and permanent uptake of the technology, by water companies in the US. Aurora Water in Colorado adopted zeta potential as primary metric for coagulation monitoring in 2010. The technology is well-established in the lab and the plant team also carried out trials with an early online system from Malvern during 2012 and 2013, reaping substantial savings as result. The primary gain has been savings in chemical coagulant usage, which has been reduced by around 20% compared to the levels used when relying on traditional analyses alone.
Tacoma Water in Washington, has a Zetasizer WT operating on a new hybrid water treatment plant that came on-stream late in 2014. The analyzer was installed early in March 2015 and has run reliably since, providing the operational team with a continuous measure that indicates whether or not the plant is running acceptably, and indicates how to change operation if it isn’t. For Tacoma Water the cost of the Zetasizer WT is more that offset by the reassurance that it provides.
‘When you look at the cost of installing the Zetasizer WT for online zeta potential measurement compared with the cost of your plant, and consider the value of truly assured operation, then it is not really a difficult investment to justify.’ says Gary Fox, Plant Manager at Green Giver Filtration Facility. ‘Having the utmost confidence in the quality of your product is essential in our industry. Zeta potential measurements allow you to keep the first steps of the water treatment under tight control, setting up the rest of the plant for reliable and consistent operation.’
To find out more about the Zetasizer WT please visit: http://bit.ly/1QL4BNu
Contact details:
Alison Vines, Malvern Instruments Ltd
Enigma Business Park, Grovewood Road, Malvern, Worcestershire, WR14 1XZ, UK
Tel: +44 (0) 1684 892456; Fax: +44 (0) 1684 892789; salesinfo@malvern.com
