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Freeze Dewatering Unit

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Value from Waste


Volume reduction


Eliminate process steps


Energy efficient


No additives


Safe and reliable operations

The FDWU is developed to separate bound water from solids. It is well suited for dewatering of sludge and sediment where the viscosity allows for the material to be pumped. Examples of industries where the FDWU can be used include:

  • Mining industry

  • Municipal and industrial wastewater treatment plants

  • Remediation and restoration projects

  • Oil and gas industry

  • Pulp and paper industry

  • Chemical and pharmaceutical industry

  • Research applications and laboratory use

  • Metallurgy and materials science

  • Energy/nuclear industry

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Fully automated, flexible and low energy freeze based dewatering solutions for a vast variety of sludges, sediments and waste materials


The FDWU pumps input materials to an intermediate buffer tank where the material is homogenized before the FDWU processes it further to the freeze cycling.

Freeze cycling

The material is cycled through the FDWU cooling tower. In this stage, the FDWU initiates water crystallization, which is a key operation to achieve separation. At this stage, water and solids separate, and also the bound water is drawn out.


After the freeze cycling is finished for a batch, the FDWU releases the frozen material which is cut into manageable pieces. The pieces are collected in an output container and from there conveyed to the Thaw Collector.

Thaw & Drying

The frozen pieces are blasted with heat exhaust from the FDWU's condenser packages, thereby achieving micro-cracking in the frozen material which heightened the performance of the thaw and drying stage. The material is conveyed for a duration and at the end of the conveyor, the material output is at the desired dry matter content. Much of the reject water evaporates and the rest is drained and released.

Collect & Create Value from Waste

Collect your dewatered material and benefit from the overall process efficency of

  • Reduced disposal costs

  • Recycling, re-process or re-use

  • Extraction of key resources from the waste

  • Low energy bill compared to thermal based dewatering

  • No polymers or chemical material or handling costs

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Plant Solutions

Siccum offers tailored solutions for your processing needs. The versatility of the FDWU makes it ideal for many different process chains with the need of achiving high dry matter substance.  It is important to ensure performance of the installations, thats why Siccum have  developed the Siccum Material Evaluation process to guarantee that no customer need or requirement are overlooked in the planning and installation process.

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How it works

Water in materials can be separated into four different categories:

1. Free water.

2. Interstitial water.

3. Surface water.

4. Bound water.

The free and interstitial water can be removed with mechanical methods. But to remove surface and bound water other methods are needed. The most common method is to use oil burners to force the water to evaporate. Another method is our freeze dewatering modules, where Siccum freeze the material to separate the surface and bound water from the material.


When water go through a state change from liquid to ice it will behave in certain ways. One physical phenomenon that Siccum make use of is, that water want to push the solids away when it go through its state change to ice. water molecules attract other water molecules and thereby create a flow towards the freezing front, the particles are ejected and clumped together. As the process continues, surface water and bound water also begin to move towards the freezing front.


With our knowledge of the this behavior of water Siccum are able to control the separation of water from the material. Thereby able to deliver targeted dry matter content of materials.

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