Water & Wastewater Treatment Magazine
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Project focus Water quality Affinity Water in metaldehyde monitoring trial Project focus A ffinity Water has taken an innovative approach to the detection of metaldehyde in a trial at a karstic groundwater treatment works in Hertfordshire with promising results. The water-only company has been working with Cambridge-based analytical technology specialists Anatune in a trial involving their gas chromatography mass spectrometry (GCMS) instrument. The instrument, which is more typically used for laboratory testing, has been adapted ● Online monitoring for metaldehyde demonstrated in Hertfordshire trial ● Lab instrument modified and employed at operational treatment works ● Monitoring will support treatment solution and catchment management efforts dealing with metaldehyde, an active ingredient found in slug pellets which makes its way into surface water and groundwater. Currently, Affinity uses other indicators such as UV absorbance in its online monitoring - backed up by lab testing - to establish the presence of metaldehyde, and this imperfect knowledge frequently means it needs to cease abstraction from particular sources, run water to waste, or import water from other regions in order to be sure of meeting drinking water quality standards for individual pesticides (0.1ug/l). Treatment to be optimised The water company is set to install activated carbon metaldehyde treatment at the site by 2020, and already has a well-established catchment management programme in one catchment where farmers are voluntarily using alternative products to metaldehyde. If successful, the improved monitoring regime will allow Affinity Water to optimise the new treatment to minimise operational cost, while providing live data which can assist in its dialogue with farmers and other local stakeholders. Since the trial began in September, the Triple Quadrupole GCMS has been operating 24/7 and is fully connected to telemetry soŠware analysing metaldehyde concentrations from three separate inlets at different stages of the treatment process. "This trial is very exciting and is generating a lot of interest in the industry," says Affinity Water Asset Manager, Debbie LoŠus-Holden. "Online water quality monitoring is currently limited to parameters such as turbidity, UV absorbance, pH and nitrates – up until now, we've not been able to do organic analysis online. Having live data on metaldehyde available within 36 minutes is going to do two things for us. It will help us with more targeted abstraction management, so we can cease abstraction from one or more so that it can conduct automated sampling at the works, providing almost real-time data to the works' SCADA online monitoring system. Using this process means that metaldehyde results are available to Affinity's operational team in 36 minutes, instead of relying on lab sampling which takes several days. The trial is part of Affinity Water's Pesticide Programme of research and development, and has been described by the water company as a 'potential game changer' for the industry in L-R: Jeff Stubbs, Ray Perkins, Alice Elder, Debbie Lo us, Henry Russell and Matthew Rawlinson 18 | MARCH 2017 | WWT | www.wwtonline.co.uk ● Monitoring will support treatment and catchment programmes for water quality ● Abstraction management will allow more efficient use of source water ● Cost of treatment processes will be optimised effectively • Drivers by James Brockett