Water & Wastewater Treatment

● UU invests in disc filtration for phosphates removal ● DynaDisc mechanical system from Hydro International chosen ● Two units to operate on 50% duty in standby system 46 | SEPTEMBER 2015 | WWT | www.wwtonline.co.uk • IN ACTION • I USED IT United Utilities has invested in DynaDisc disc filtration technology from Hydro International to improve phosphates removal at its Congleton and Saddleworth wastewater treatment works and meet Urban Wastewater Directive water quality targets. The DynaDisc installations have been put in at both plants in a project to supplement secondary trickling filter beds treatment. Contractor Nomenca also installed new dosing systems and integrated the new equipment with existing instrumentation systems as part of United Utilities' AMP5 investment programme. Both DynaDisc units are capable of treating 100% of the final effluent flow, but will normally operate at 50% duty with standby to ensure continuous service. The wastewater treatment works had to meet new phosphorous consent limits of 2 mg/l based on the Urban Wastewater Directive. Congleton, in Cheshire, also had to meet an aluminium consent of 1mg/l, while Saddleworth, in Greater Manchester, faced an iron consent of 2mg/l. The DynaDisc systems were allied with a polyaluminium dosing plant and ferric sulphate dosing plant respectively in order to meet these consents. Focus on… filtration Products The DynaDisc mechani- cal disc filtration system offers high efficiency microscreen filtration which can be tailored to wastewater composi- tion, flow and discharge requirements. It is made up of modular disc- shaped screen cassettes covered with fine woven filter media to specified pore sizes, suspended on a rotatable sha within a drum. Key benefits include a very compact footprint, low head requirements and high suspended particle removal. As part of the filtration process, the removed solids and backwash are returned through the site systems for treat- ment. The filter water is then used as the supply WhAT ElSE IS NEW? Severn Trent purifica- tion business sold Industrie De Nora has completed its £60M-plus acquisition of Severn Trent's water purification business. The new business will be called De Nora Water Technologies (DNWT). Carbon nanotubes explored for filtration Scientists in China have discovered that the use of carbon nanotubes can lead to more efficient water filtering. The tiny hollow structures are able to filter impurities without impeding flow. placement of cassettes with a minimum of fasteners. A constant level tank allows any variations of flow rate to be accommodated, and minimises the filtered water retained by the vessel whilst still providing a reservoir for the backwash pump. A variety of filter cloth can be used within the system to suit the desired application. Typical applications involve DynaDisc be- ing used for tertiary solids removal in both activated sludge and trickling filter plants. Industrial applications include purification of process water and cool- ing water recirculation. Phil Algawi, Project Manager for Nomenca, says: "We were asked by United Utilities to look at a range of options for improving phosphates removal at the two sites. One of the criteria, apart from meeting the set limits, was to expand the range of technologies that United Utilities was using so as to have a more diverse range of solutions. "Before recommending the Hydro solution to United Utilities, we examined the operation of a DynaDisc at an established site elsewhere in the country and were very impressed with its operation. Hydro worked with us very professionally to achieve an installation that met the specifications of a compact site and satisfy the requirements of United Utilities. We found DynaDisc easy to install, connect to the existing site systems and commission. Following the installation we conducted a fourteen day trial, which was a success." of washwater to clean the filter cloth when the headloss through the filter reaches a pre-set level. Considered engineering design is used to keep the seal length to a mini- mum and allow quick re-

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