To meet the discharge requirements of an environmental licence, all the wastewater from a landfill site had to be treated before being discharged into the surface water. There are two types of water flows on the site, which is located in Sint-Gillis-Waas, Belgium. On the one hand there is the leachate water from the landfill, and then there is also potentially contaminated rainwater, which falls on the landfill and needs to be collected and sent to the wastewater treatment plant. Given the heterogeneity of the former landfill site, and the potentially different composition of future deposits, the client wanted a flexible system that could remove a wide range of pollutants.
A special water treatment plant was designed that can remove the most common organic pollutants, most heavy metals and even ammonium, but this is to a limited extent. The plant has a hydraulic capacity of 10 m³/h. Variations in flow are buffered in a newly designed reception basin. In the aerated influent buffer, the oxidation of iron, manganese and organic components occurs.
Subsequently, ferric chloride and polymer are dosed in a pipe flocculator to capture the dissolved heavy metals, which leads to the formation of sludge flocks. The pH, ranging from pH3 to 12, is corrected slightly in order to allow the flocculation to take place. The iron sludge is then separated in a settling tank and disposed of periodically.
The water runs from the outlet of the settling tank into a mixing tank where chlorine oxidation of nitrogen compounds (ammonium) can be performed. The remaining suspended solids are then captured in an automatic, cleanable sand filter. Thereafter, the dissolved organic compounds are removed in activated carbon filters. After the filters there is an optional ion exchange to polish any residual concentration of heavy metals or to remove certain ions, such as cyanide. Finally, the effluent is discharged into the surface water.
Based on a modular containerised system, the plant is fully automated and can be monitored and controlled remotely. We are also responsible for monitoring the installation and the preventive and curative maintenance.