Water & Wastewater Treatment

WATER TREATMENT some cases 24 months. The exceptions were a small minority of Yorkshire water sites that had very high manganese levels. AT, working closely, with Yorkshire Water's water quality scientists and project managers did identify a few sites would need to be buffered. A combination of unusually high pH, large pH swings and high iron and manganese concentration issues were the contributory factors in the selection process. Around 10% of the installations run with buffer. The AT monitors, however, use very small amounts of reagent, 25l/year compared to 25l/month with the incumbent systems, due to the unique low-volume flow cell in the new technology. Technology focus: chlorine Chlorine is the most widely used disinfectant in domestic settings. However, it is also used in industrial settings for the purification of water. Chlorine is used to destroy agents that can cause disease, such as viruses or bacteria, and therefore pose a risk to human health. It also leaves a residual that can be controlled and measured to monitor chlorine levels. Despite its main function as an effective water purifying agent, chlorine is also useful for other purposes in water treatment plants. These include the removal of iron and manganese, bleaching of certain organic compounds and prevention of algae growth. Chlorine monitoring is of great significance to water management and supply services as chlorine also has its associated drawbacks. Excessive levels of chlorine in drinking water or water used for washing can have an effect on the respiratory system and can also cause taste and odour problems. Chlorine has a long history of safe use for hygiene purposes; however, the World Health Organisation has provided a health-based guideline that no more than 5mg/l of chlorine should be present in water. Installation AT supplied and installed 450 Q46H62 free chlorine monitors, which have been engineered to overcome the traditional issues associated with buffered amperometric monitors. The monitor features a variable water quality pH correction algorithm which allows the monitors to de deployed in processes that derive their raw water from all types of sources - rivers, boreholes, surface water et cetera. The standard AT pH sensor is designed to work over a very wide range of conductivities reducing any pH errors. Around 50 Q45H79 Total Chlorine monitors were also supplied to the sites with high and varying pH and high iron and manganese levels. These monitors provide the same accuracy and reproducibility as the free chlorine monitors. In order to provide YW with the most efficient and effective system, AT designed bespoke single and triple-validated chlorine monitoring boards which were installed on every sample point throughout the process, to ensure full disinfection control in accordance with their best water quality practice. All signal marshalling, power supplies and the entire 'wet end' were custom designed to allow quick and easy replacement of existing monitors with minimum disruption to operations. The investment in design time up-front dramatically reduced the time needed on site and reduced the installation cost for the scheme. Training All the instrumentation was installed in three phases over a two-and-a-half-year period, allowing for the plants to continue operating while adapting to changes in requirements. Following installation, AT then provided full operational training to Yorkshire Water employees. The final phase of Analytical Technology's framework agreement was successfully Perspectives The client "Now that the roll-out is complete, the scheme has realised around £336K of OPEX savings per annum, and operators will no longer have to manhandle 25l containers of buffer around our sites. ATi has provided an excellent service and it is a pleasure working with a company who are very customer focused. "The high level of technical support that Analytical Technology provides really differentiates the company, and all staff have extensive knowledge of their products. The monitors also run without reagent in the majority of installations, resulting in cost savings and Analytical Technology has tailor-made a solution to fit our needs rather than just supplying a monitor." Alan Henson, project manager, Yorkshire Water The Operator "The asset replacements were well managed on site, and everyone worked together to minimise risk to water production and any other site issues. AT working closely with Yorkshire Water also resolved the SCADA issues on each site, sorting out RTS [remote test station] alarms and left every site clean and tidy, something which is not always the case. "This extra 'added value' has helped Operations in their day-to-day jobs." Rod Black, production manager, Yorkshire Water completed in May 2013, with 103 chlorine monitors installed throughout sites in the south area. This included a mixture of buffered, bufferless and pH corrected units, which were deployed depending on water quality and expected pH range. These monitors were installed into a total of 52 water treatment plants and nine secondary chlorination sites throughout Yorkshire Water. The utility has replaced its region-wide chlorine monitoring system with monitors that are more efficient, reliable and cost effective. The intuitive interface of the monitors enables operators at YW to easily calibrate and operate the instruments. 20 Water & Wastewater Treatment January 2014 In the vast majority of installations there is also no longer any need to handle 25l containers of buffer around sites. In addition, the chlorine monitors supplied help to achieve compliance with EU directives, as well as the stringent internal guidelines set out by YW. AT's monitors work within the parameters required by these directives. AT's Q46H monitors have proved to be extremely easy to maintain and operate and provide reagent-less operation in the majority of applications. The roll-out has resulted in an operational expenditure saving of up to £336K a year and whole-life cost savings of up to £5.37M. nnn wwtonline.co.uk

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