Water & Wastewater Treatment

30 | october 2014 | WWt | www.wwtonline.co.uk The work not only generated energy efficiencies, it saved money by reducing on-site operational requirements Project focus: Pumps & pumping systems sludge at the required temperature and solids content throughout the changeover from the thermal drying process to the HPH plant. During that period the thermal drying process was shut down and decommissioned so that the necessary changes could be made to re-direct pipework, connecting the digest- ers to the new HPH plant. Once the thermal drying process was no longer available, Anglian Water stored waste from the Pyewipe sewage works at other locations as cake, until the new process was fully operational. In the meantime, the sludge in the digesters was brought to a consist- ent 6% solids and 39 °C temperature ready for the switch over. The HPH plant is now fully opera- tional and a new mixing system for the digesters means that the submers- ible pumps are no longer required. "Our 2 new 1.2 megawatt CHP plants process methane from the sludge and are used to generate power for the boilers and site which can provide sufficient steam to heat the digesters to the required level on an as needed basis," says Jennings. "It is an extremely energy-efficient solution, with the sludge at both the beginning and the end of the energy generation cycle." For more info go to wwtonline.co.uk dress that fall in temperature quickly in order to keep the switch over to the new HPH plant on schedule." Bridging the gap Anglian Water contacted pump hire specialist Sykes Pumps, to help ad- dress the situation by sourcing and installing temporary pumps that were better able to cope with the increased dry solids content. Sykes Pumps sales director Chris Graham explains: "We are a preferred supplier for Anglian Water and have a local depot in Scunthorpe close to the Pyewipe site, which meant we could have pumps down there on the same day to tackle the treatment works' immediate needs." "Once we had provided a stop-gap measure to prevent any further tem- perature loss in the sludge, we could then take a step back and recommend an ideal solution to raise the tempera- ture up to 39 °C and keep it there." Sykes Pumps installed two diesel pumps within 24 hours of the first enquiry from Anglian Water. These ensured that the higher solids content was circulated more effectively, rais- ing the sludge temperature. However, as the pumps were required to run on a 24/7 basis, this was not the most cost-effective long term solution. "We were able to provide silenced diesel pumps immediately, which fulfilled the task and minimised noise on site, but the most efficient and cost-effective solution was to use an electric submersible pump on each digester," says Graham. "We were able to locate specialist wastewater submersibles and get them installed on site within two days of the initial enquiry." Commissioning and decommissioning The submersible pumps remained on hire for four months, managing the "It soon became clear that the pumps simply couldn't cope and instead of increasing the tem- perature of the sludge, we were actually seeing a drop in temperature." John Jennings, Anglian Water • Perspectives John Jennings, treatment optimiser, Anglian Water: "The project represented an investment of £28M and was a key part of our strategy to improve effi- ciency, enhance capacity and reduce operational costs. "With such a significant project there is always an element of the unexpected and finding that the pumps could not circulate the sludge effectively once we started to increase the solids content could have been a major setback. That's why it's so important to work with suppliers that can respond quickly and advise on a best-fit solution. "The fact that Sykes Pumps was able to put an interim solution in place immediately and then get the specialist kit to site so quickly meant that we could continue to focus on the major challenges of modifying our process and keep the cap-ex scheme on schedule." Chris Graham, sales director, Sykes Pumps "Because pump hire is so o en driven by the need to provide a solution to a challenge that the client has encountered while a project is being delivered, our business is geared up to respond quickly with both specification advice and fast installation. "Ours is a solutions- based business and we were therefore able to put a quick fix in place while we worked on providing the best long term option."

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