A dairy processor produces milk powder by extracting water from milk in a vacuum evaporator. Approximately 15% of the milk becomes powder and about 85% is water. The water must be evaporated under vacuum to separate it from the solid components.
After condensation, the water is discharged as warm wastewater at about 30°C and contains a small amount of fat. Before entering the municipal sewer, this fat must be separated. At the company’s wastewater treatment plant, a settling tank collects fat at the water surface, where a layer approximately 2–3 cm thick forms each day. A floating open trough was used for separation, but the recovered mixture contained about 80% water and only 20% fat. Because the fat was highly viscous, the surface also required manual cleaning with a scraper, and the water-fat mixture had to be sent to a waste contractor.
To reduce disposal costs, the customer sought a food wastewater oil skimmer capable of separating the fat with as little water as possible.
At a maintenance trade fair in Munich, the company’s maintenance manager saw a FRIESS S100 oil skimmer in operation. Its simple design and reliable removal of floating fat immediately impressed the Bayerische Milchindustrie eG team. The manager initially questioned whether the collection tube could remove the viscous fat. During a site visit, the local FRIESS representative demonstrated the technology with a tube sample. Pulling it through the floating fat showed clearly that fat particles and globules adhered to the tube. The test also showed that the collection tube is unsuitable for very thick fat layers of 5 cm or more, because a hard layer forms and particles no longer adhere effectively.
The maintenance team and the FRIESS representative agreed to test an S100 oil skimmer under operating conditions. Before installing the rental unit, the hard fat layer was removed manually. Once the surface was clean, the skimmer was installed and started. The test showed that fat particles adhered to the collection tube and were removed as soon as they appeared at the surface. During operation, the water surface remained almost clean and no new fat layer formed.
The oil skimmer reduced the water content of the recovered fat to below 20%. Even with the rental system, the company achieved a substantially better recovery value and lower waste-disposal costs.
