Water & Wastewater Treatment

www.wwtonline.co.uk | WWT | APRIL 2014 | 25 Aeration has been part of the treatment process at Worcester WwTP for nearly a century Project focus: Severn Trent site trial Benefits The Lontra Blade Compressor was first run at Worcester in September 2012 and aer running full time as a 'duty blower' without issues for more than seven months, STW acknowledged its core reliability and performance. The site's instrumentation and supervisory control and data acquisition system (SCADA) showed that the conventional blowers used more than 20% more electricity to deliver an equivalent amount of air when compared to the Lontra Blade Compressor. These remarkable results prompted Severn Trent Water's chief executive Tony Wray, in his presenta- tion of preliminary results to the City in May 2013, to report that, were the Lontra Blade Compressor to be rolled out across all of Severn Trent's WwTWs, the com- pany could save more than £1.8M a year in electricity costs, with a commensurate reduction in the company's overall carbon emissions of 3%. The magnitude of the potential sav- ings was enough for STW to consider a large-scale replacement programme. To confirm the savings beyond doubt, it was decided that the on-site instrumen- tation for the Blade Compressor and the comparative blower should be upgraded to laboratory standard. Consultants ABB were engaged to specify and supply the instrumentation and the flowmeters were replaced by brand new Orifice plates to ISO standard 5167. The data from this instrumentation was logged for seven months between June 2013 and December 2013 over all conditions, from summer to winter, to give a view of the true saving potential of the Lontra Blade Compressor in a fully operational wastewater treatment works. "Our upgraded instrumentation showed that the Lontra Blade Compres- sor used, on average, 21.2% less electric- ity to deliver an equivalent amount of air when compared to the existing blowers, which is a really positive result", said Jones. "Importantly for us, as well as being efficient, the machine is simple, using well understood and proven materials and engineering. This fits well with the needs of an industry that needs minimal downtime and long service life from its assets." He concluded, "The Blade Compres- sor has now run for more than 10,000 hours, the equivalent of more than three years of normal operation, without is- sue. This gives us significant confidence in its reliability." The Lontra Blade Compressor was voted the Most Innovative New Technol- ogy at the 2013 Water Industry Achieve- ment Awards. www.wwtonline.co.uk • Perspectives The client "We have worked closely with Lontra over a number of years to bring to reality the tremendous potential of this very clever invention. This technology should make a significant contribution to the business efficiency challenges we have, to allow us to keep bills low for our customers. We look forward to taking the next steps together to make the most of this exciting development." Mark Jones, wastewater R&D manager, Severn Trent Water The supplier "Severn Trent Water's long-standing support for the Blade Compressor has ensured that we develop the compressor in the context both of the commercial priorities of the water industry and the technical specification for compressors for activated sludge aeration. The Carbon Trust's support is hugely valuable in bringing the project together, and recognises the substantial carbon reduction potential in improving efficiency in wastewater aeration." Simon Hombersley, business development director, Lontra • Innovation ● Severn Trent saw the tremendous potential in Lontra's revolutionary Blade Compressor, which takes the traditional compressor's basic design and engineering principles and gives them a new spin – literally! ● With a traditional piston and cylinder, as the piston drops down in the cylinder it draws in air above it and, as it goes up again, it compresses air in front of it. The Lontra Blade Compressor is best imagined as a piston and a cylinder, but with the piston wrapped around inside. ● There is a constantly open intake port, without valves. As the piston rotates, it induces a volume of air behind it in the same way as the piston dropping down in the cylinder. ● As it gets back to the starting point, it has induced a complete volume behind it. However, unlike the traditional piston and cylinder that has to stop and change in direction, the blade passes through the disc with the volume that was trapped behind the piston now in front. ● This means that it has an almost continuous cycle of inducing air behind and compressing air in front, a new geometry that is quieter, smoother and highly efficient.

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