From the 19th century, coal has been converted to coke at a large facility in Zeebrugge. During the process, PAHs, benzene, naphthalene, cyanide, sulphates and nitrates were released, which have contaminated the groundwater. Due to the proximity of the sea and the Boudewijn Canal the groundwater also has a high salt content.
The extracted groundwater is first treated with primary flocculant and poly-electrolyte in order to flocculate the suspended solids. Subsequently, the formed sludge settles in a settling tank which is emptied periodically.
After aeration, the water is successively treated by means of sand filtration, bags filtration, active carbon filtration and ion exchange. The treated water is eventually discharged into the surface water.