Gravitox

While the activated sludge procedure that was developed at our Davyhulme wastewater treatment works in 1914 is reliable, effective and used worldwide, it does require a lot of electricity to power the machinery needed. Sewage is aerated to allow bacteria to 'eat' harmful micro-organisms and other pollutants. But with power-hungry surface aerators involved, companies like us can spend tens of millions of pounds on energy every year.

Gravitox - a project funded by the Carbon Trust - could offer acompelling alternative.

Although currently only a laboratory demonstration, Gravitox is a promising technology that could reduce the energy consumption of our aerated sludge process by up to 75 per cent.The idea is that by drawing a fluid down a specially created borehole, and the smart use of pumps, we can increase hydrostatic pressure, dissolve air and increase the oxygen transfer to the liquid.

So, with the relatively low cost of drilling a borehole and basic construction work, we can depend less on our current surface aerators, which consume a lot of electricity.
The low capital costs of implementing Gravitox, coupled with the potentially vast energy savings makes this innovation one we're committed to investigating further.

Ian Carline studied Environmental Chemistry at University of the West of England (UWE) before joining UU. He's since worked on several research and design projects involving the optimization of biological processes in Enzymic Hydrolysis and sludge digestion.

Ian has vast experience in pilot plant design, construction and operation in all areas of wastewater treatment. For the last two years, he's helped to support the knowledge transfer programme at Ellesmere Port and in January 2009 became project engineer for Gravitox.