Customised system

For flue gas cleaning, where condensate appears or external scrubber liquid is added, the pollutants are transferred from gas to water. Discharge of such wastewater requires cleaning to applicable strict emission standards. RADSCAN INTERVEX has developed a cleaning system to relieve wastewater from these pollutants, including dissolved metals, fine-grain ash, and dioxins also from dissolved gases, as ammonia, sulphur oxides and hydrogen chlorides.

Broad system knowledge

There is no standard apparatus for water purification. Instead we design for each individual process water a customised system, consisting of necessary functional stages, dosing equipment for chemicals and measuring and control instruments.

Sand filter

Generally the cleaning is done as follows:

Precipitate
The metals are precipitated as hydroxides, by raising the pH to 8-10. To manage the low emission values for mercury and cadmium, these are precipitated as sulphides.

De-gasification
Is done by "stripping" the liquid with combustion air. This is done in a reactor with a surface enlarging inset, where the liquid is finely dispersed over the inset and meets the air on it's way through the stripping tower.

Flocking
Precipitated metals, fine grain ash and dioxin most often appear as small particles difficult to separate. By using additives the particles agglomerate into larger clusters, where after these are separated gravimetrically or by sieving.

Particle separation
Gravimatic separators
In these the flow of liquid is laminar with such low velocity, that the particles settle. The average distance between particle and sediment surface is kept narrow, which promotes sedimentation. The remaining particle content after the gravimatical separation is normally 20-40 mg / l.

Sieves
When filtering using the sieve effect, cartridge filter drum sieves etc., are used. Cartridge filter can be selected to give a remaining particle content after filter of 10 mg / l. The automatically cleaned drum sieve RECO-LW is suitable for high liquid flows and high particle load. It can be selected to separate particles down to 20 mm.

Sandfilter
With demand of very low particle emissions, (less than 10 mg /l), sand filter is used, either alone or as a final filter after gravimatical separators or sieves.

Carbon filter
For example. mercury, cadmium and dioxins the demands are so stringent, that further process stages in some cases are necessary, e.g. adsorption with activated carbon.

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