Dehydris™ Twist - Boosted Sludge Dewatering Using Piston Press Technology



Based on proven Bucher Unipektin piston press technology (with more than 2,000 food industry references), Dehydris™ Twist represents one of the most innovative and efficient systems in the dewatering market.

Dehydris™ Twist Technology...

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 effi ciency required (dryness or flow rate). Each cycle is made up of three, entirely automated, main phases:

Supply phase: The cylinder-piston unit is closed and rotation started. The piston moves back and forth; at each return stroke sludge is fed into the unit until the nominal volume in dry matter has been reached. Sludge is automatically introduced into the unit and concentration and flow rate measurements are recorded.

Pressing/filter cake fragmentation phase: The piston continues to go back and forth whilst the entire cylinder-piston unit continues to rotate: granulation of the sludge by the drainage elements during the return stroke allows renewed contact to be made between the sludge and the fi ltering media, thus facilitating the release of interstitial water trapped during pressing. According to the incoming dry content and the volume of extracted water, this phase is stopped at a precise, automatically calculated value on a return stroke.

Discharge phase: The cylinder casing slides along the machine axis uncovering a part of the pressing chamber. The cylinder/piston rotation continues while the piston moves forward. The dewatered sludge fi lter cake is discharged by gravitational force, helped by the drainage elements, which tips during rotation. Emptying is automatically performed in only a few minutes.


Product Videos

Dehydris™ Twist
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The Dehydris™ Twist process is explained in this video animation


Product sheet

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Main Advantages

    • 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 autothermicity 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.