How does a slurry separator work?

A slurry separator separates the slurry into two parts: a solid phase and a liquid phase. Pressure is applied to separate the substrate into two fractions: a homogeneous, pumpable press water and a dry, stackable solid. For many agricultural, municipal and industrial businesses, separation is now a central component of modern slurry and fermentation residue management. It reduces storage space requirements, improves application and supports biogas technology by stabilising the fermentation process and increasing gas yield.

Below, you can find out how a slurry separator works technically, how the process works step by step and how Paulmichl separators prove themselves in practice.

How a slurry separator works, explained simply

A modern slurry separator works using a mechanical separation process and is pressure-controlled: the slurry is sucked in by a pump and pumped to the separator. In the separator, the substrate is conveyed by a screw conveyor built into a sieve basket. The screw conveyor separates the substrate into solid and liquid components as it passes through the sieve basket. The aim is to achieve a stable, uniform and economical separation effect.

The process consists of several steps:

• Suction of the slurry: Feeding is usually carried out using a self-priming eccentric screw pump, which transports the substrate directly from the pit or pre-tank into the separator. Foreign objects such as stones are separated beforehand to protect the pumps and screens. In addition, the substrate should be sufficiently homogenised beforehand.
• Conveying and pre-pressing: In the separator, a rotating screw transports the slurry towards the screen. The pressure increases continuously during this process – the basis of separation.
• Separation at the screen basket: The liquid medium flows through the stainless steel screen, while the solids are transported further towards the discharge. The screw continuously cleans the screen through friction, ensuring reliable operation. Fibrous materials in the screen gap are reliably cut off by the sharp-edged design of the screw and transported out of the screen gap by the pressure of the screw.
• Regulation of dry matter content: A pressure flap or other counterpressure system allows the desired dry matter content of the solid phase to be adjusted using weights – important for bedding, composting or biogas substrate management. The correct selection of the gap width and the geometry of the screen basket and press screw are also decisive factors here.
• Discharge of solids & removal of press water: The solids fall out of the separator as plugs and can be discharged directly. With mobile devices, the solids can be transferred to a conveyor belt or a discharge screw. The press water flows out via a free drain or, optionally, via an additional press water pump.

The result: a stackable solid phase and a very homogeneous, free-flowing liquid phase that is easier to pump and spread more evenly.

Find out more here in the field report from the Müller dairy farm.

Advantages of separation at a glance

✓ Targeted and precise application of nutrients for optimal fertilisation
✓ Quickly absorbed thin slurry with significantly less plant contamination
✓ Versatile solids for use as bedding, compost or biogas
✓ Up to 20% additional storage volume in the slurry tank
✓ Improved operational nutrient balance through targeted release of surpluses
✓ Reduced environmental and odour pollution through treated slurry fractions
✓ Higher yields through more efficient and crop-oriented nutrient utilisation
✓ Reduced mineral fertiliser requirements and long-term cost savings
✓ Homogeneous, pumpable press water for precise application technology
✓ Stackable solid phase for easy recycling and transport