After the closure of a gas plant in Diest, Belgium, the site was found to be heavily contaminated with BTEX, PAHs and cyanides, so it was crucial that it was remediated.
To treat all the drainage water and the extracted groundwater, a water treatment plant was designed so that the effluent met the discharge standards of the surface water. The plant comprised a biological wastewater treatment system, a stripping tower followed by an air-activated carbon filter, an automatic sand filter, water-activated carbon filters and ion exchangers.
The Sequencing Batch Reactor in the treatment plant reduced the nitrogen content and removed the organic BTEX chemicals and naphthalene as much as possible. The BTEX contamination was then removed by means of the stripping tower, and the PAHs were further removed by activated carbon filters. Before the water was discharged into the surface water, cyanides were removed by means of an ion exchanger.
A telemetry system with alarm signals was also installed so it was possible to respond quickly and efficiently to any malfunctions in the system.