Water & Wastewater Treatment

BETWEEN FREE PASSAGE AND HYDRAULIC EFFICIENCY The SE and SL ranges offer the highest total efficiency yet in a wastewater pump Highest wire-to-water efficiency: The best yet, reducing your total costs and making life easier Best hydraulic efficiency: No compromise on free passage, meaning better solids handling and greater non-clogging capabilities Continual operation: Unprecedented reliability from high motor and mechanical efficiency, with all aspects of pump operation controlled intelligently The SE and SL ranges of wastewater pumps provide the highest total efficiency currently available. Innovative technologies from Grundfos bring together intelligence, motors, hydraulics and functionality to meet the challenges of modern wastewater, maximising the hydraulic, electrical and mechanical efficiency of your pumps. See more at uk.grundfos.com/no-compromise.html NO COMPROMISE 10697_SE_SL_annonce_210X297_WWT_ART01_JW.indd 1 4/14/14 10:35 AM www.wwtonline.co.uk | WWT | MAY 2014 | 9 Comment M odern sewage treatment became 100 years old on April 3. The story started in Davyhulme, Manchester with a revolutionary new process called "activated sludge". Here at United Utilities scientists from around the world have come to Manchester to celebrate with us and learn more about this innovation, which had an enormous impact around the world. Before 1889 Manchester was served by a network of local sewers that tended to discharge untreated e€ uent into rivers and streams. As the population grew, this situation was untenable and solutions had to be found. Before the treatment plants were set up sew- age from the growing industries was discharging into the rivers. It was so bad that there was a report around 1891 that claimed one of the rivers was so polluted that the birds could hop across it on the scum that was formed. However, innovation was on its way. In 1914, two Manchester Corporation employees based at Davyhulme sewage works called Edward Ardern and William T Lockett invented a new process Activated sludge – past, present and future Centenary of modern sewage treatment called 'activated sludge'. It harnassed the power of micro-organisms and meant that waste from millions of people could be treated in a relatively small space. This factor alone enabled cities to grow and develop. What the activated sludge process did was reduce the amount of land you need to provide the equivalent level of treatment. The new process was published in a scientiŒ c paper on April 3, 1914. Sewage treatment plants around the world use the system to this day. The initial invention looked at nutrient re- moval as well, speciŒ cally at removing nitrogen and phosphorus. Interestingly, we are still draw- ing a lot on what those initial inventors did. The basic biology and chemistry is still the same. Davyhulme treatment works The spirit and foresight of Ardern and Lockett a century ago has not waned. There is evidence that the desire to test, improve and innovate has been an important part in the development of the Davyhulme's wastewater treatment works, which opened in 1894, over the years. In 1918 a large-scale plant was installed at Davyhulme using the activated sludge puriŒ ca- tion method, operating a Œ ll-and-draw system, which was superseded by continuous ' ow, with di' users to create bubble aeration. The plant at Davyhulme was treating 4.5Mld by 1920 and the di• culties with disposal of surplus activated sludge were resolved by co- settling with sewage prior to aeration. Turning to today, the new thermal hydrolysis digestion plant (Sludge Recycling Centre) at Davyhulme is the largest of its kind in the world. It takes a problem waste stream, the sludge le™ over a™ er sewage treatment, and converts it into renewable electricity and a high-quality fertiliser for farmers.š Later this spring the story continues as a £200m modernisation project gets underway at the plant. By 2018 the oldest parts of the site, some dating back to the 1930s, will be replaced with the latest energy-e• cient equipment. Challenges for the future Overall, our main future challenge is the Water Framework Directive. The continued pressure on the environment means that nutrient removal will become more and more of a driver for us. We already have tight e€ uent standards at Davyhulme and even more ammonia will need to be removed in the future. Phosphorous removal could also become necessary at Davyhulme and we would need to consider the most sustainable way of treating for this. It is likely that recovery of phosphorous from the waste will be a key consideration for the future as this is an essential chemical for life and natural global resources are being depleted. There is a lot of innovation at present around nutrient removal and recovery of phosphorous. It is an area in the Œ eld of wastewater treatment that has continued to develop since it Œ rst came to prominence in the 1970s. The activated sludge process and its variants will give us a resilient and sustainable solution. MARIE HART HEAD OF ENGINEERING DISCIPLINES UNITED UTILITIES "Without the invention of activated sludge – the world – not just Manchester – wouldn't be how it is today. You wouldn't have the capability to sustain large, urban developments that you do now. In terms of its importance to the world's social and economic development it's been a really important invention." PHIL SWEENEY AREA BUSINESS MANAGER UNITED UTILITIES

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