• The Stjernholm grit washer system for dairy farms separates grit from slurry. The grit can be re-used and the slurry can be used for biogas production.

In close co-operation with agricultural experts, consultants in the dairy industry, veterinaries and dairy farmers, Stjernholm has developed a range of products and acquired unique process knowledge which allows to offer a turn-key solution when it comes to separate sand from slurry, clean the sand and reuse it in the stalls of larger dairy units. Former difficulties handling slurry containing sand can now be eliminated resulting in improved animal welfare and increased profitability.

Stjernholms’s focus is to develop and market technical solutions and systems for the treatment of slurry containing sand, for farmers in Denmark and abroad. With us, you will find a professional partner capable of delivering high quality and reliable machinery working to your benefit and to the welfare of your livestock.
Stjernholm is established in 1997 the company develops, manufactures, markets and installs a wide range of quality equipment for domestic and industrial waste water treatment. Stjernholm products are well known for their high quality and reliability. Adapted to the requirements in agricultural applications Stjernholm products create a solid base for the equipment delivered.

Farming

Every dairy farmer using sand beddings is well acquainted with the challenges in handling slurry containing large quantities of sand..

Opicon’s customised solutions help dairy farmers to meet these challenges, offering simple, reliable and smart systems to handle slurry containing sand.

Opicon’s proces of handling slurry with sand is unique. It is based on many years of development, experience and application of equipment to handle sand holding waste water. Today, the proces is fully adapted for the application on agricultural sites with installations running in both Denmark and abroad.

The proces consists of three steps:​

  • Separering of sand and slurry.
  • Cleaning of the separated sand for reuse.
  • Handling of sandfree slurry, e.g. by separation into at thin and thick fraction for use on biogas plants.

The Opicon sand/slurry separation proces reduces expenses for buying new sand and eliminates, the cost of removing sand sediments in storage tanks. Sandfree slurry can be stored and spread or used on biogas plants without the problems sand containing slurry normally would cause with these activities.

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The process consists of three steps:

  • Separation of grit from slurry with a retention percentage of up to 99.6 %. That means that only approx. 1 g of grit is left per litre of separated slurry.
  • Cleaning of separated grit for re-use.
  • Secondary treatment of grit-free slurry with the option of managing the dry matter percentage, for storage, delivery or use in biogas facilities.

The criteria for a smooth grit washer system function are:

  • 90% or more of the grit must be separated.
  • Following the washing procedure, the grit must contain such a low level of bacteria and fibres that it can be re-used after just a few days of storage.
  • The slurry must be sufficiently free of grit and rich in biological dry matter that it is suitable for biogas production.
  • The criteria for a smooth function are drawn up based on customer needs and each individual situation.
  • In co-operation with the customer, we define the criteria and select a method for sampling and test analysis at approved laboratories.

THE BIOGAS PRODUCERS’ SLURRY REQUIREMENTS

The content of grit and biological dry matter in the processed slurry is highly important to the financial aspect.

Apart from gaining certain economic benefits through improved productivity and fewer veterinarian bills, the content of grit and biological dry matter is highly important when choosing a grit washer system.

A high level of grit retention minimises expenses for new purchases and allows for delivery to biogas production facilities. Furthermore, a high percentage of dry matter provides an income from selling slurry for biogas production.

SLURRY REQUIREMENTS
FOR BIOGAS PRODUCTION
VS*GRIT/LITREINTEREST
< 70
> 10 g
Rejected
> 75
< 5 g
OK
> 78
< 2 g
OK
> 80
< 1,5 g
OK
> 83
< 1 g
OK

*) Organic content in dry matter.

Organic content in dry matter test carried out by Stjernholm A/S:
VS > 83 and grit per litre < 1 g.

DRY MATTER (DM) PERCENTAGE
IN DELIVERED SLURRY
DMTRANSFER PRICE/TON
8%
DKK 0
9%
DKK 4-6
10%
DKK 8-12 *)
11%
DKK 12-16
*) 1,000 COWS PRODUCE 90 M3 PER 24 HOURS. WITH A DRY MATTER PERCENTAGE OF 10% AND A TRANSFER PRICE OF DKK 10 PER TON, THAT AMOUNTS TO DKK 328,500. IN SETTLEMENT FROM THE BIOGAS PRODUCTION FACILITY. OPICON GUARANTEES MIN. 9% DRY MATTER IN WASHED SLURRY.

Watch a video from milk producer Erik Dolby here

The video is also available in Danish, Spanish, Chinese and Dutch.
© Stjernholm A/S 2020