Water and Effluent Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/763461
10 WET NEWS JANUARY 2017 Driving out odour issues at Saltend WwTW • With odour levels at its Saltend WwTW having reached 'unacceptable' levels, Yorkshire Water opted to replace the existing rake drive system. projEcT SpEcS • Replace the original rake drive system in the lamella tanks at Saltend WwTW • Specify and install the final drives • Complete scheme within a tight timeframe A nyone working in the UK wastewater treatment industry will be familiar with the type of problems faced by Yorkshire Water at the Saltend Wastewater Treatment Works (WwTW), where long- standing issues around odours disturbed the local community, most notably during the peak load season (late June-August) when the flows into the site peak. Announcing an investment of £30M to address these issues last October, Yorkshire Water's improvement works are now complete with Warrington-based Brevini UK having been awarded a contract which sees it again working on environmental improvements for the residents of East Yorkshire. High output For this major project, Brevini was commissioned to work on the Morgan Sindall Sweco (MSS) joint venture, specifically to replace the original EIMCO rake drive system in the lamella tanks – a significant part of the whole wastewater treatment plant at Saltend. With a very tight timescale – Yorkshire Water set a target for major improvements to be operative for summer 2016 – Brevini had only an eight- to ten-week turnaround to cover concept, design, rapid pricing, manufacture and installation on site for a solution that would interface with existing kit at the plant. Brevini's breadth of product portfolio meant it was able to consider a number of potential solutions, before specifying and installing the final drives. As a general rule applications in the water industry tend towards high output torque and low (or very low) output speed requirements, which make planetary drives the optimal solution. The major exceptions to this would normally be aerators and Archimedian screw drive units but, even here, a planetary solution is suitable for a large proportion of the low- medium power ranges. Brevini offers both helical and planetary gear solutions, as well as a hybrid gear unit – the compact Posiplan range, which features a final helical gear stage, and one or more planetary or spiral-bevel input gear stages, and the option to fit a labyrinth oilseal. For the Saltend project, most gear unit suppliers would consider providing a simple gear unit as a replacement, particularly given the very tight turnaround from commission to completion as this would minimise the risk of problems with specification, design and manufacture, with an in-line planetary unit seeming the most obvious selection. However, the gear unit is only a small part of the system. There would have to be an output coupling of some form, selected to transmit the output torque required, plus supporting Main: The original drive is removed from the treatment works. Inset: Bridge transition pieces had to be installed to accommodate the drive assemblies The drive assemblies are fitted to the rake-arm column ONSITE OdOUR CONTROl