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Gravity Drainage Deck

Dewatering for thinner sludge

Gravity Drainage Deck, 3m GDD in workshop

The Gravity Drainage Deck is a simple yet effective sludge thickening solution that meets the needs of various industries, providing a practical and economical waste management solution.

Introducing the Gravity Drainage Deck (GDD): Efficient mechanical sludge thickening

SIEBTECHNIK TEMA Gravity Drainage Decks are used to dewater thinner sludge, with low suspended solids of 0.3-1.5 %. We manufacture the GDD’s in our factory in Revesby (greater Sydney, NSW) and have supplied over 60 units to various industries over the past 30 years.  In many processes, the Gravity Drainage Decks is coupled with a Belt Filter Press (BFP), thus feeding thickened sludge to the BFP for more effective dewatering.


Typical applications for the Gravity Drainage Deck include

  • Sewage Treatment Applications: The GDD is highly effective in treating various types of sewage sludge, including raw waste activated sludge, primary sludge, and both aerobically and anaerobically digested sludge.
  • Other water treatment applications: It is also adept at handling sludge from extended aeration ponds, sludge from dissolved air flotation, and sludge from alum-lime water treatment processes.
  • Industrial Applications: The GDD is used extensively in industrial settings, particularly for the treatment of waste sludge from the pharmaceutical, food and dairy processing industries. It is also effective in treating sludge from paper mills, tanneries and abattoirs.
  • Power and steel mill waste: In the power and steel sectors, the GDD efficiently treats fly ash and sinter waste sludge, making it a valuable tool for waste management in these industries.
  • Mineral Processing Wastewater: The GDD is also suitable for managing wastewater from mineral processing operations.


How does the Gravity Drainage Deck work?

The Gravity Drainage Decks operates on the principle of free drainage of liquid by gravity. This process is facilitated through a porous belt, enhanced by a plow turning action, which helps to effectively separate the liquid from the solids in the sludge.

Benefits of the Gravity Dewatering Deck:

  • Compact design: The GDD has a small footprint, making it suitable for facilities where space is at a premium.
  • Cost-Effective Installation: It is economical to install, providing a budget-friendly option for sludge thickening.
  • Low maintenance and operating costs: The GDD is designed for easy maintenance, resulting in lower operating costs.
  • Reduced sludge transport costs: By thickening the sludge, the volume that needs to be transported is reduced, saving transportation costs.
  • Improves drying bed performance: The GDD speeds up the drying bed process, making overall sludge handling more efficient.

Optional Extras

The Gravity Drainage Deck comes standard with a complete set of features for efficient operation. These include a flocculation tank equipped with a 0.37 kW mixer, safety lanyard switches for emergency stops, low air and water pressure switches, and belt drift switches for alignment control. It also includes guards and a mechanically variable main drive that is compatible with variable speed drive (VSD) control systems (provided by others).

We generally offer the following optional extras:

  • Other dry sludge handling equipment such as conveyor belts, sludge bins etc.
  • On site installation by our service technicians
  • On site commissioning assistance by one of our engineers

Materials of Construction

The Gravity Drainage Deck’s frames are constructed of epoxy-coated mild steel for durability and corrosion resistance. All parts in contact with the water, such as the filtrate trays, flocculator tank, spray bars, and fasteners, are constructed of 316 stainless steel and the rollers are rubber covered for improved performance and longevity.

In addition, there is an option to manufacture the frames entirely in stainless steel, providing an alternative for those seeking this specific material for their equipment.

2m Gravity Drainage Deck installed on site
Gravity Drainage Deck with protective cage - 0,5m GDD
Gravity Drainage Deck in use
Gravity Drainage Deck, 3m GDD in workshop
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