CODECAL^®, an efficient process for sludge treatment

 

The use of lime for sludge conditioning before dewatering in filter presses (pre-liming) is a widely used concept.

 

In centrifuge dewatering, lime is usually not used for pre-liming, as it hydrolises organic polymers by the high pH that lime brings. 

For sludge hygienisation, usually compulsory for agricultural recycling, an additional post liming step is commonly practiced, mixing lime with the centrifuged sludge.  However, this has the disadvantage of de-structuring sludge making it more "pasty" and adding an additional step into the process. 

 

The CODECAL^® process, developed by CARMEUSE, enables the use of quicklime for pre-liming (sludge conditioning) in centrifuge together with organic polymers, combining the advantages of the filter press process with those of the centrifuge.

After mixing, CODECAL® enhances a perfect flocculation at all pH values, including >12, and then reacts exothermically with the water of the sludge only after dewatering.  The relatively coarse particle size compared to hydrated lime mineralises sludge, enhancing the dewatering to an even greater extend. This technique enables to by-pass the post-liming step, ensuring a perfectly homogeneous and consequently guaranteed hygienised mixture while using less reagents and emitting less bad odours.   On plate filter presses, CODECAL® makes lime introduction easier, by direct dosage instead through a milk of lime solution, while enhancing the dewatering by the mineral effect that it brings.