Water & Wastewater Treatment

www.wwtonline.co.uk | WWT | november 2014 | 33 In the know Research round up: pipes and pipelines T he water distribution networks of England and Wales are age- ing faster than we can afford to replace them; at the current rate of replacement, new assets would need a lifespan longer than a century in order to maintain operations. At the same time, public expec- tations and austerity politics put pressure on network managers, who must find operational savings while Pipedreams: Exploring the world of biofilms within pipe networks The secret to managing water quality in ageing networks is to stop thinking of the network as a pure engineering problem, and wake up to the biological world within also delivering service improvements – new ways to do more with less, to make do and mend. As such, tomor- row's replacement strategies must be targeted for optimal value for money, and less expensive interventions deployed wherever possible. The Challenge But how to decide where, when and how best to intervene? The Pipe- dreams project began with the premise that any thorough understanding of water quality (WQ) risk must be rooted in an understanding of what goes on inside the pipes, and especially on the pipe's internal surface. For while a WDN can (and must) be understood as a complex hydraulic system, it is also a bioreactor, a microbial ecosystem teeming with life – and the environ- mental conditions of that ecosystem turn out to have a lot to do with discolouration, the WQ failure most prevalent and apparent to customers. Methods The Pipedreams project has focussed on biofilms. In layman's terms, a bio- film is a build-up of organic gunge on the inner surface of a pipe; its matrix is largely made up of carbohydrates and proteins, and acts as a support structure for colonies of microbes and as a 'sponge' for accumulating inor- ganic material from the bulk water. These biofilms accumulate with time, until some hydraulic event or another manages to break them free from the pipe surface – which is when you'll start getting discolouration complaints from disgruntled customers. The jewel in the project's crown is a unique and world-leading experimen- tal facility based at Sheffield. The facil- ity comprises 600 meters of 79mm- diameter HDPE pipe in three isolatable loops, each equipped with storage tanks, WQ instrumentation, pumps ProfEssor Joby boxall Pennine WaTer GrouP universiTy of sheffield Paul ravEn Pennine WaTer GrouP universiTy of sheffield Key points ● robust WQ prediction and management offers an alternative to costly asset replacement ● Discolouration events are caused by changes in hydraulic regime which dislodge "biofilm" from the inner pipe surface ● Hydraulic regimes can be managed so as to minimise build- up and mobilisation of biofilms, thus avoiding discolouration events ● Predictive WQ models offer a field-ready toolset for strategic planning ● Increasingly affordable monitoring technologies could lead to live event detection and systems management in the control room The University of Sheffield research facility features 600m of pipes in three isolatable loops

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