WET News

18 WET NEWS FEBRUARY 2017 the High Floc Alarm, where the Sludge Finder 2 makes a secondary assessment of the raw data being analysed and looks specifically for an increase of floc rising close to the top of the process but sitting above the level of the main blanket. Enabler The effective control of the floc layer has meant that some sites have now managed to completely automate the final treatment process. At Barnhurst, a Severn Trent Water site in the West Midlands, 14 Pulsar Sludge Finder 2 systems are relaying data back to a control cabin via radio telemetry links to adjust bellmouth valves, controlling the process automatically to create a 'healthy' sludge level in the clarifiers. Call-outs have been significantly reduced, minimising costs, but the key point here is that this critical compliance control process can now be safely trusted to an automated system, even in final treatment where sludge concentration is very low. Bellmouth valves are one control mechanism, but this THE CONCEPT • Measurement is achieved by profiling the echo so that the changes in density can be identified • A piezo electric crystal in the Viper transducer produces a pulse that is reflected throughout the liquor inside the tank • The Viper transducer incorporates a sweeping arm that keeps the face clean • The Sludge Finder 2 can make a secondary assessment of the raw data being analysed NEED TO KNOW 1 Non-contacting ultrasonic technology has become the standard technique throughout the wastewater industry 2 Sludge at the Stoke Bardolph site is concentrated from 2% to 6% before being processed further in onsite digesters 3 Sludge measurement has historically been a very hit and miss affair 4 A submerged transducer still has issues around fouling THE VERDICT "Call-outs have been significantly reduced, minimising costs, but the key point here is that this critical compliance control process can now be safely trusted to an automated system…" Alistair Mackinnon, Pulsar approach could just as easily be applied to penstock or decant arm operations. Good sludge blanket detection is an important enabler in sludge concentration operations for green energy generation. At Severn Trent Water's Stoke Bardolph site, sludge is concentrated from 2% to 6%, before being processed further in onsite digesters and then used to power turbines that help to make the site self-sufficient in energy. This sort of project is very much in line with the 'spend to save' approach that supports totex strategies. As the old saying goes, 'garbage in, garbage out'. Without accurate, reliable monitoring and measurement, with equipment that is manageable and easy to set up, it would not be possible to rely on the control protocols and, by extension, some of these projects would be difficult, more time consuming and in some cases impossible. n Alistair Mackinnon is director of sales and marketing at Pulsar Process Measurement. HEAVYWEIGHT CHAMPION OF THE DRAINAGE WORLD When the going gets tough, the tough get concrete. Installation costs can be lower than lightweight systems, thanks to less reliance on expensive granular bedding and the labour-saving Pipe Lifter. And concrete's inherent strength and durability mean lower lifetime costs in terms of money and carbon. With systems proven by 150 years' service, concrete is the undisputed heavyweight champion of drainage. Why pick a lightweight? For details, visit www.concretepipes.co.uk THE HEAVYWEIGHT DRAINAGE CHAMPION CONCRETE CPSA Boxer Master 250x176.indd 1 04/08/2016 20:14 Submerged Pulsar Viper transducer mounted on moving bridge

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