A separator splits slurry into a solid and a liquid fraction. The farm gets solids it can use as bedding or compost, the store is left with thinner slurry that is easier to mix, and spreading is more even without clogged hoses. One such machine is the Stallkamp PSS 2.2-400 press screw separator, which won a gold medal for innovation at the AGRA fair in Gornja Radgona in 2016, as the manufacturer also reported in its news section. Kancler Sistem Pro is Stallkamp's Slovenian partner. Below we explain how the separator works, what you get out of the slurry and when the machine pays off.
What the AGRA gold medal means
The AGRA fair in Gornja Radgona is a fixed date for Slovenian farmers and machinery dealers, and a gold medal for innovation there is a well regarded recognition. Exhibitors can put their new products forward for the competition. In 2016, a panel of specialist journalists and industry experts judged the entries on design, performance and technical novelty and awarded a gold medal to the Stallkamp separator.
How a press screw separator works
A pump feeds the slurry into the inlet chamber, from where a screw moves it through a cylindrical screen with narrow slits. As the slurry is pressed, the liquid runs out through the screen and returns to the store via an overflow or a pump. The solids travel on to the outlet, where they are held back by a hydraulic cone head. The cone creates counter-pressure: the higher it is, the drier the solid fraction. The pressure is shown on a gauge, so the desired dryness can be set during operation and repeated later.
The award-winning PSS 2.2-400 is a compact model with a stainless steel housing, an armoured stainless steel screw and a 2.2 kW gear motor. According to the manufacturer, it can produce solids with up to about 32% dry matter. In the ComPress mobile unit, the separator is combined with a rotary lobe pump and electronic control, with an optional chassis. It is designed mainly for smaller quantities, and the system can be expanded later. For higher throughput, Stallkamp offers larger PSS and PSG separators, the latter with a cast housing.
What you get from one tonne of slurry
Stallkamp gives a theoretical calculation: one tonne of slurry with 8% dry matter yields roughly 900 kg of liquid with about 5% dry matter and around 100 kg of solids with about 30% dry matter. The actual result depends on the slurry, the counter-pressure setting and the size of the separator, which is why the manufacturer recommends a trial with slurry from your own farm.
Nutrients are not split evenly between the two fractions. With cattle slurry, the manufacturer's experience is that roughly a fifth of the phosphorus and around 15% of the nitrogen end up in the solids, while most nutrients stay in the liquid.
Where the solids and the liquid go
Bedding in cubicles. Solids that are dry enough can be used as bedding. The farm produces it itself, when it needs it, and so buys less straw. The condition is good cubicle management: the bedding must be topped up regularly so the bed stays level and the material does not heat up, and it should be used fresh. We described what a cow expects from her bed in our article on lying stalls and cow comfort.
Storage, composting and transport. The solids behave much like farmyard manure. They can be kept on a manure pad, composted or taken to more distant fields, because moving concentrated nutrients costs less than moving whole slurry.
Liquid in the store. When the liquid returns to the pit or lagoon, the store contains less dry matter and fewer solids. This slurry is easier to mix, and the mixer uses less energy to homogenise it. We are happy to help you choose one as part of our range of slurry mixers.
Spreading. Thinner slurry spreads more evenly, does not clog hoses and soaks into the soil faster. Storage and spreading of both fractions must, of course, follow the current fertiliser regulations.
When a separator pays off
A separator is a one-off investment, but the benefits add up: less bought-in bedding, relief for the store, easier mixing, simpler spreading and cheaper nutrient transport. The more of these benefits a farm uses, the sooner the investment pays back. Stallkamp also developed its compact mobile separator for smaller farms and considers it worthwhile from about 80 cows.
Slurry separation is easiest to include during barn planning, when decisions are made about slurry routes, space for the separator and storage for the solids. That way the separator fits in sensibly with the rest of your cattle farming equipment, from cubicles to water troughs.
Need advice?
Stallkamp is a German manufacturer of slurry technology, from tanks and pumps to separators and mixers, and Kancler Sistem Pro is its Slovenian partner for advice, sales and installation. If you are thinking about separating slurry, tell us your herd size, housing system and storage setup, and we will suggest a suitable solution.
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