Home >  Services in Europe >  Industrial waste services > Treatment of sludge 

Treatment of industrial sludge

Sludge is not an isolated waste problem. The entire production process of each type of sludge will be examinated thoroughly as to find an economic, legal and ecologically sound method for the extraction of sludge.

There are different types of sludge:

  • biological or organic sludge originating from all industrial branches
  • physico-chemical or inorganic sludge originating from specific industrial branches: water collection, steel industry, chemical industry, petrochemistry, etc.

Treatment

Sludge is a waste material that usually contains a large amount of water. The water should be properly removed. The removal of the water is often initiated by adding chemical substances to the sludge, such as FeCl3, FeCl2 (Ca(OH)2, CaO, polyelektrolytes, inert products, etc. The pre-treated sludge will then be drained in specialised mechanical or thermal installations.

 

Filter cakes

Purification of waste water results in filter cakes. Depending on their compositon, these cakes will be treated in a different way:

  • If the filter cakes are 'non-hazardous', they can be burned in the Indaver's grate incinerators.
  • ‘Hazardous’ sludge streams and its derivatives have to be treated in Indaver’s rotary kilns.
  • A series of sludge streams with low contamination of heavy metals or other worrying contamination elements can also be treated by co-incineration in for example cement kilns or coal driven power plants.
  • Inorganic sludge streams that contain an exceptionally high amount of leaching metals or anions are treated in the solidification unit.
  • The residue is deposited in a landfill class 1 site. Filter cakes that comply with the legal criteria for disposal can be discharged directly to a landfill class 1 site such as the Indaver site in Antwerp.
  • Sludge streams that contain mainly biologically degradable materials can be transported for possible composting or fermentation. This sludge may even be applied as a means of soil improvement, provided it meets the stringent criteria required.