Veolia Water Technologies & Solutions

Biosolids Sludge Dewatering Solutions

Boosted wastewater sludge dewatering with a piston press

The Dehydris* Twist unit is based on the Bucher Unipektin piston press, which is fed with drinking water sludge or pre-thickened wastewater sludge conditioned with reagents (polymers possibly mixed with mineral reagents).

The press, equipped with semi-solid drainage elements, operates in cycles (from 2 to 3 hours). The length of the cycle depends on the type of sludge and efficiency required (dryness or flow rate). Each cycle is made up of three, entirely automated, main phases:


Dewatering Sludge Treatment Features


    • increased productivity with a possibility of non-stop operation (24/7) without the need of a staff presence, smaller foot-print than a filter press.


    • high dry content obtained without the addition of lime: up to 40% for drinking water sludge and auto-thermicity achieved for urban wastewater sludge, versatile: accepts both drinking water and wastewater sludge (mixed sludge, fresh, digested, thickened or primary).


    • enclosed and ergonomic industrial process 100% automatic operation including emptying.

    • up to 30% reduction in sludge bulk compared to conventional dewatering.

What is the Dewatering of Sludge?

What is dewatering in wastewater?

Wastewater has a solids component within it.  Separating the solids from the wastewater allows each proponent to be treated optimally.

What is sludge and how is it treated?

Sludge is typically treated by digestion.  Digestion gets the sludge into a more stable form for disposal and minimizes the volume. 

What is sludge dewatering?

Sludge dewatering is the process by which water is removed from solids.  Typically local regulations dictate the requirement for the transportation and land application of sludge.  Anaerobic digestate is approximately 5 – 8% dry solids.  In order to get the solids into cake form, 20+% is required.   

What is the sludge treatment process?

Digestion, drying and thermal oxidation can be utilized for treating sludge.

Why is Sludge Treatment Necessary?

Raw sludge is not a stable product and therefore cannot be land applied or sent to a landfill.  Therefore some sort of treatment is required.



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