Municipal sludge is typically liquid containing 2 to 6 per cent solids prior to mechanical dewatering. The thin sludge enters the drying line and is first mechanically dewatered in a decanter centrifuge or belt press. This is a cost-efficient process that brings the dry substance of the sludge up to 25-30 per cent and accomplishes both weight and volume reductions. The dewatered sludge is then fed to the drier, where indirect heat is used to evaporate water from the wastewater solids in order to bring the dry substance up to approximately 40 to 45 per cent. The heat value of the dried solids is thereby high enough to provide for an optimal energy balance in incineration plants.
The Haarslev TST dryer is indirectly steam-heated and designed for high capacity, gentle drying and consistent product quality.
For condensing vapors from cookers and dryers used in meat rendering and fish meal plants, using liquid as the cooling medium.