Whatever field you are in, being a pioneer entails equal parts determination and innovation. At VWT UK, we understand this process, having brought a number of industry-firsts to different markets throughout our history. Recently, we completed a first of its kind glycol removal plant at Heathrow Airport. Here, Barry Hallam, Project Manager at VWT UK, explains how the unique system, which we designed, built and installed is now helping the site to treat its biological wastewater more effectively.
Glycol is an organic compound, most commonly found in antifreeze solutions, like de-icer. The solution is frequently used during winter months to de-ice aeroplanes, eventually making its way into wastewater run-offs. Unfortunately, even when diluted, glycol can still pose a toxic threat, which is why Heathrow Airport wanted to remove it from its wastewater discharge. In doing so, the famous airport would also move one step closer to its overarching environmental goal; to prevent the discharge of any contaminants into nearby rivers.
So how does the new solution work? The pioneering technology functions as an aerobic wastewater treatment method and includes an AnoxKaldnes™ Moving Bed Biological Reactor (MBBR), chemical conditioning, Hydrotech Discfilter and drum thickener. To begin with, the innovative glycol removal plant takes water from a runway collection lagoon and pumps it into two MBBR tanks operating in series. It is also dosed with nutrients for the biology within the MBBR tanks which work to breakdown organic material in the water. Once processed by the tanks, any solids are separated from the MBBR treated water via the coagulation process. The water is dosed with coagulant and polymer before being passed through a Hydrotech Discfilter. Finally, the treated water is discharged into a separate ‘clean’ side of the collection lagoon. Once this process is completed, the water is safe to be released into the nearby River Crane, a tributary of the River Thames. Meanwhile, the backwash wastewater from the Discfilter is dosed with more polymer and the solids are separated via a drum thickener. Finally, the solids, or sludge, from the drum thickener is tankered off site and disposed of.
Thanks to its design, our MBBR system is able to provide the optimal culture conditions on which bacteria can grow, using active biofilm carriers with large surface areas that are made from plastic to achieve the most effective result. The carriers are constantly kept in motion using aeration, allowing the bacteria to break down organic material in the wastewater. Then, the large surface areas of the carriers in our patented AnoxKaldnes™ MBBR systems enable the treatment of a high quantity of wastewater using a very small footprint.
This bespoke solution, which was initially developed and tested at AnoxKaldnes’™ laboratory in Sweden is decommissioned during the summer and reactivated in Autumn, ready for use during the colder months, when it is most required.
On top of its effective design, the project team at Heathrow was also impressed by our ability to offer a full service solution, enlisting us to design, supply, install, commission and operate the plant. VWT UK will continue to operate the new plant for the next ten-years having secured a further operations contract, which began in December 2019.
So far, the team at Heathrow is really happy with the build and the initial trial of the technology has proven to be very successful. This has not gone unnoticed by other facilities across Europe. Moving into the new year, we hope that we will be able to use this technology and our expertise in its application to help other airports and similar facilities remove one of the most harmful contaminants from their effluent wastewater discharges. What’s more, we will be helping to improve the health and wellbeing of local rivers, as well as the plants, animals and fish that call them their home.
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