For 30 years, trout have been cultivated at the Winkelmann farm in Wietzendorf (Lower Saxony), southeast of the city of Soltau. What started out as a hobby ultimately became a business. Since then, the main goal has been the preparation of fish eggs, caviar (roe).
The female trout are brought up in concrete semi-circulating basins and slaughtered after 26 to 29 months as salmon trout. The annual fishing quota is 650 - 700 tons. The company itself sells the caviar throughout the world. The fresh fish goes to processors.
“Spa area” for fishes
“A fail-safe supply of oxygen is mandatory for our breeding tanks”, explains junior manager Stephan Winkelmann. This supply ensures not only the oxygen vital for the fish to breathe, but also a constant circular flow of water. The fish constantly need to swim against the flow of water to remain active.
For an optimal supply, approximately 7 kilogrammes of pure oxygen dissolved in the water is required per tank each hour. The corresponding compressed air require- ment is approximately 10 - 12 cubic metres per minute per tank. Winkelmann covers this requirement exclusively with compressed air produced by AERZEN’s positive displacement blowers. Only in the case of higher temperatures does additional pure oxygen need to be provided via surface aeration or ceramic diffusers.
Highest security of supply
“Since the start of the intensive breeding, we produce the required oxygen exclusively with AERZEN positive displacement blowers”, says senior manager, Hermann Winkelmann. Even now, the first units in- stalled in containers operate continuously around the clock - without showing any signs of wear. In parallel with the extension of the breeding tank, nine further ma- chines of the current series Delta Blower “Generation 5” work in a central location at Winkelmann. Seven units of type GM 25 S are driven electrically and two machines of type GM 60 S have diesel motors.
At the same time as the commissioning of the circular tank in mid-2014, three additional electrically-driven units and one diesel- powered unit were installed. In order to be well prepared in case of a longer power failure, the company also has two emergency generators.
... and energy efficiency
“Besides the high security of supply, the- re is one further argument in favour of AERZEN positive displacement blowers”, says Winkelmann. “Thanks to these machines we produce the oxygen with optimal energy efficiency. This is a very important consideration for us, as energy costs are a principal component within our overall profitability calculation. Only when the entire company works economically, it is possible for us to sell our products successfully in the market.”