The existing water treatment installation at Indaver NV, Antwerp, which treats the water streams coming from the flue gas treatment implemented on the rotary kilns, has reached the end of its lifetime. Based on several tests, the international waste management company developed a process scheme that formed the basis for the design for a new installation that would replace the current one. Purazur NV was responsible for the detailed engineering, construction, testing and commissioning of the new wastewater treatment plant.
A new physico-chemical water treatment plant was built for the treatment of the water streams.
This installation consists of the following consecutive steps:
- Pre-neutralisation by dosing of Ca(OH)2
- Neutralisation and coagulation by dosing of Ca(OH)2 and FeCl3
- Complexation with TMT
- Flocculation with polymer and precipitation with Na2S
In the last step the flocculated water runs to three parallel settling tanks. The clear water is discharged at the top and flows to the sewer. The sludge settles at the bottom of the tank and is pumped to two sludge buffers, which are equipped with a light conical bottom and a slowly rotating racking bridge.
After thickening, the sludge is further dewatered in a vacuum belt filter press. The resulting sludge cakes fall onto a transport belt system which transfers the cakes to a sludge container. The transport belt system is equipped in such a manner that the cakes are equally divided over the container. Furthermore, the installation is equipped with a platform at a height of 1 m below the top of the reactors in order to ensure that all parts of the installation (valves, instrumentation, mixers) are reachable in a safe and ergonomic way.