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Gravity Belt (GBT) and Rotary Drum Sludge (RDT / PDR) Thickeners – Andritz

Andritz GBT & RDT thickeners for efficient sludge treatment. The GBT has large open area, special feeder, and adjustable ploughs to optimize the drainage effect.

Rotary Drum Thickener (RDT) / Power Drum Thickener (PDR)

Considered to be an easy and efficient thickening solution prior to the dewatering process and can deal with biological sludge.With its simple design and small footprint, the PowerDrum is easy to install and requires little supervision and maintenance.

  • Durable technology (all stainless steel design) for very low wear,
  • Reduction in sludge volume (up to 90%) before storage or shipment•
  • Intermittent or continuous self-cleaning thanks to a stainless steel spraybar with PVDF nozzles
  • Low power consumption and, consequently, low operating costs
  • Entirely closed system to avoid odor pollution
  • Easy maintenance and fast belt removal
  • Efficient and reliable design
  • Dedicated cover for washing ramp access, with automatic rotation of the ramp to give direct access to nozzles for inspection or cleaning
  • Additional hatches for drum inspection and cleaning


Gravity Belt Thickener (GBT) – Andritz

After the sludge is flocculated in the feeding pipe, it enters the gravity zone where most of the liquids and solids are separated. A spreader plate ensures uniform distribution over the working width of the belt. PowerDrain units can be equipped with two to four rows of ploughs which compact, rearrange, and deflect the sludge. The thickened sludge is scraped from the belt. The filtrate is discharged on the drive side. A washing chamber with flat jet nozzles cleans the belt. As an option, the spray bar can be equipped with a self cleaning device. The thickened sludge is now ready to be processed by dewatering equipment.



  • Thickening before a filter press
  • Thickening of municipal or industrial wastewater sludge
  • Thickening before anaerobic digestion