Reliable solids measurements for centrifuge control
Dec 19, 2023
Vaasa Water’s Pått wastewater treatment plant, located in Finland, cleans the wastewater of the entire city of Vaasa and part of the wastewater of the neighboring municipalities of Korsholm and Malax.
The wastewater treatment plant was drying its sludge with a centrifuge, mainly on weekdays only, which meant that the efficiency was not the best possible. The drying result was evaluated visually from camera footage which did not provide the exact dry content, and the centrifuge was at times adjusted manually through an automation system. The dry content was analyzed weekly at the plant’s laboratory.
With the centrifuge approaching the end of its lifecycle, the decision was made to replace it with a new one. The starting point for the procurement of the new centrifuge was that it would operate fully automatically 24/7, without a crew. Operation without personnel and the optimal use of the centrifuge require several continuous measurements, which were supplied by Valmet.
The whole project (a new centrifuge, measurements, and controls) paid for itself in about 1.5 years through the considerable savings in the reprocessing costs of the dried sludge.
We are very happy with the equipment delivered by Valmet, as well as the after-sales services.
Timo Auranen, Instrumentation Technician
Summary
Location
Vaasa Water’s Pått wastewater treatment plant, Finland
Customer challenge
The procurement of a new centrifuge for sludge treatment at the wastewater treatment plant was started in 2020.The starting point for the new centrifuge was that it would operate fully automatically 24/7, without a crew.
New centrifuge, measurements and control solutions were needed.
The centrifuge runs continuously at the best possible massflow (kgTS/h).
Polymer dosing before the centrifuge also adapts to the sludge total solids.
Valmet DS is used as the measurement of the dried sludge to monitor whether the desired dry content (~28%) is achieved.
The whole project (centrifuge, measurements and controls) paid for itself in about 1.5 years through the considerable savings in the reprocessing costs of the dried sludge.
