WET News

WN August 2016

Water and Effluent Treatment Magazine

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AUGUST 2016 WET NEWS 13 AUGUST 2016 WET NEWS 13 SCOTLAND'S FLAGSHIP ANNUAL WATER CONFERENCE The 5 th WWT Water Scotland Conference is the only event that brings together the whole sector to share leading case studies and strategic expertise specific to Scotland. Roseanna Cunningham MSP Cabinet secretary for environment, climate change and land reform Alan Sutherland Chief executive officer Water Industry Commission for Scotland Peter Farrer Chief operating officer Scottish Water Terry A'Hearn Chief executive officer SEPA Lucy Darch Managing director, Northumbrian Water Group Business David Grzybowski Data manager Drinking Water Quality Regulator Keith Aitken Journalist, author and broadcaster EXPERT SPEAKERS INCLUDE CHAIR BOOK NOW www.wwt-scotland.net SCOTLAND WATER CONFERENCE 5 OCTOBER 2016 | GLASGOW SUPPORTED BY SUPPORTED BY • Hear the latest on retail competition both in Scotland and south of the Border • Learn how the sector is tackling floods and SuDS through regulation, collaboration and modelling • Share ideas on how to drive a cutting-edge and efficient sector through innovation FOLLOW US @WWTlive #waterscotland The use of UV as a primary disinfection is on the increase, offering significant savings in operational costs. T he water industry, with good reason, is very conservative and the familiarity of chemical disinfection by chlorine or ozone, easily monitored by redox potential, is somehow reassuring whilst monitoring electromagnetic radiation is largely unfamiliar – in spite of the fact that the pharmaceutical industry has relied on UV disinfection for over a quarter of a century. However, more and more water companies are discovering that UV as a primary disinfection strategy reduces the environmental, health and safety risks associated with large scale chlorination or ozonation and gives significant savings in both capital equipment expenditure and operational costs. The efficacy of UV disinfection is dependent on the dose of radiation required to handle the microbiological load. The third factor is the UV transmissivity of the water – this is a measure of how much of the applied radiation is absorbed by the water. The lower the transmissivity the higher the applied dose has to be to achieve the required dose. But the critical factor is how the UV dose is delivered and that depends on the design of the UV reactor. UV disinfection has been used for water supply in the US for more than ten years and, rather than re-invent the wheel, the DWI UV Disinfection Guidelines closely references the US EPA guidelines for equipment validationiv. This requires validation by independent third-party bioassay to the EPA protocols. Validation testing by biodosimetry uses the log inactivation of specific challenge microorganisms passing through a UV reactor, in combination with known UV253.7nm dose-response relationships, to determine a corresponding Reduction Equivalent Dose (RED) and, therea'er, a validated dose for A solution: Going ultraviolet target pathogens. Minimum required REDs derived during reactor validation are expressed in terms of a UV253.7nm equivalent dose. Once the RED for the specific reactor type has been validated then the control system has to maintain it over the full range of works flows and UV transmissivities by monitoring UV intensity in each reactor and automatically adjusting the dose. Not all UV reactors are capable of achieving this. The first UV systems in the water supply industry were, not surprisingly, installed on good quality borehole sources with high UV transmissivity and fairly constant flows. With increasing experience, and growing confidence, the technology is increasingly replacing traditional chemical systems on surface water sources. The growth has been impressive. The number of atg UV Technology systems delivered under AMP5 has topped 50, including plants for Affinity Water, South East Water, Southern Water, Sutton & East Surrey Water and Thames Water, with three systems for Portsmouth Water under construction. So, the future looks good for UV disinfection but manufacturers are far from complacent. New developments include high output, ultra- efficient 800W Amalgam UV lamps like atg UV's 800W UVLX series. These offer a range of benefits including guaranteed lamp life of 16,000 hours, optimised UV reactor design for reduced head loss and a low installation footprint. The ultra-high output of the 800W Amalgam UV lamps reduces the number of lamps, quartz and seals by more than 50% by comparison to traditional 330W systems, giving significant capital and operating cost savings. Barry Hopton is municipal business manager at atg UV Technology. Cryptosporidium inactivation achieved with UVLW systems featuring ultra-efficient 800W Amalgam UV lamps designed to provide optimum flow distribution and hydraulic performance

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