SPECIAL WORKS
VWT UK help Heathrow hit an Environmental Milestone
Veolia Water Technologies UK (VWT UK) has recently completed a pioneering glycol removal plant at Heathrow Airport, the first of its kind to treat glycol in this application in the UK.VWT UK was selected due to its expertise in water treatment technologies and services – and for the cost-effective, yet bespoke solution its experienced team put forward.
The aim of the project was to provide a biological wastewater treatment plant to treat the glycol runoff from the airport runways prior to its discharge into the river Crane. An organic compound from the alcohol family, glycol is commonly found in antifreeze solutions and, as such, is used as a de-icer on aircrafts during the winter months.
For Heathrow, it was necessary to create a solution that could be kept in a semi-ready
state throughout the summer, for use during cold spells when the glycol is used on aircraft and present on the runways. The new plant is part of Heathrow’s environmental ambition to prevent the discharge of any contaminants into the river Crane in the future.
After a competitive bid, VWT UK was selected to design, supply, install, commission and operate the plant. This means that the leading provider of water treatment technologies and services will continue to operate the new plant for the next nine-years - having secured a further operations contract which began in December 2019.
The new glycol removal plant takes water from a runway collection lagoon, processes it and discharges it into a separate four-part clean water lagoon, prior to
its release into the river Crane. The plant itself includes two 1,100 m3 AnoxKaldnes Moving Bed Biological Reactor (MBBR) biological treatment tanks, through which the effluent passes.
Next, the water enters a coagulation tank, followed by a flocculation tank before the solid flocs are filtered through one of VWT UK’s Hydrotech Discfilters. The filtered solids, or sludge, are then thickened and disposed of while the treated water is discharged to the clean side of the lagoon. In total, the plant processes 720,000 litres of runoff water per hour and 550kg of biochemical oxygen demand (BOD) per day.
An aerobic wastewater treatment method, MBBR systems use active biofilm carriers made from plastic with large surface areas on which bacteria can grow with optimal culture conditions. The carriers are kept constantly in motion within the tanks using aeration, allowing the bacteria to break down organic material in the wastewater – in this case BOD, of which glycol is rich, and ammonia. The large surface area of the carriers in the AnoxKaldnes™
64 | October 2021 |
www.draintraderltd.com
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