Gratt Centrifugal Decanter
Quality and tradition in effluent treatment!
The Gratt Centrifugal Decanter is a high-efficiency solid-liquid separation equipment designed for continuous clarification, thickening, sludge dewatering and raw material recovery operations in industrial processes.
Using the principle of centrifugal force, the system significantly accelerates the natural sedimentation of particles, promoting fast, stable and high-performance separations, even in effluents with a high solids load.
It is widely applied in both production and post-processing stages, allowing the recovery of value-added products, reducing disposal volumes and adapting effluents to current environmental legislation.
What is a Centrifugal Decanter?
The decanter centrifuge, also known as centrifugal decanter or horizontal centrifuge, is a machine designed for the continuous separation of phases with different densities.
Its mechanical set consists of:
- Rotating cylindrical-conical drum;
- Conveyor helical thread (helicoid);
- Pressurized feeding system;
- Continuous discharge system for solids and liquids.
The drum and helicoid rotate in the same direction, but at slightly different speeds (differential speed), an essential condition for the continuous transport of the separated solid.
How does it work?
The separation occurs due to a difference in densities, enhanced by high centrifugal forces (G-force), much greater than gravity.
When the mixture enters the drum at high speed:
- the solid phase (denser) is projected against the inner wall;
- the liquid phase (less dense) remains in the central region.
This stratification promotes rapid and efficient phase separation.
Advantages of the Gratt Centrifugal Decanter
Process steps
Step 01 – Food
The homogeneous mixture is introduced through a feeding tube directly into the rotating drum.
Step 02 – Centrifugal acceleration
The material is immediately subjected to high rotation, generating intense centrifugal forces that accelerate the sedimentation of solid particles.
Step 03 – Formation of the solid ring
The solids settle on the inner wall of the drum, forming a compacted layer.
Step 04 – Mechanical transport
The helical screw, rotating with a speed differential, continuously drags the solids along the drum towards the conical discharge zone.
Stage 05 – Solids discharge
The dewatered material is continuously expelled from the solids end, reducing volume and facilitating transportation, stacking or final disposal.
Step 06 – Output of the clarified liquid
The clarified liquid flows through the opposite end, being collected by internal spillways and directed for reuse or subsequent treatment stages.
Differences
Gratt is a pioneer in the manufacture of Centrifugal Decanters in Brazil, with more than 6,000 units installed in the country and abroad.
The equipment stands out for:
- High solid-liquid separation efficiency;
- Continuous and automatic operation;
- High product recovery yield;
- Lower consumption of physical area;
- Exclusive and patented regulation systems;
- Excellent performance with concentration variations;
- Easy maintenance;
- Long service life;
- Technical know-how consolidated over more than 39 years.
They are a national reference in two-phase separation machines.
Applications
Recommended for clarification, solids recovery, thickening and sludge dewatering processes in:
- Industrial Waste Treatment Plants (ETDI);
- Water Treatment Plants (ETA);
- Effluent Treatment Stations (ETE);
- Food industry;
- Refrigerators and slaughterhouses;
- Dairy products;
- Beverages;
- Feed and by-products;
- Chemical industry;
- Fuels and biofuels;
- Mining and minerals;
- Between others.
Operational control and adjustments
Gratt Centrifugal Decanters have exclusive regulation systems that allow precise adaptation to process conditions.
Among the main controls:
- supply flow modulation;
- differential speed adjustment;
- helical torque control;
- adjustment of the depth of the liquid mirror;
- adaptation to variations in solids content.
This set guarantees operational stability even under large load fluctuations.
Construction
Gratt Decanters are designed for severe industrial operation, with a focus on mechanical robustness, reliability and long service life.
Constructive features:
- Reinforced structure for high rotation;
- Dynamically balanced drum;
- Helical thread with high wear resistance;
- Internal components prepared for abrasion and corrosion;
- Industrial sealing system;
- Motorization and drives; designed for continuous operation
- Compact set, easy to integrate into the plant.
The design is designed to withstand large variations in solid load without loss of performance.
