DAF2 Dissolved Air Flotation Machine for WWTP Sludge Thickening and Concentration Our DAF2 Dissolved Air Flotation Machine (Model DAF2-ST Series) provides efficient sludge thickening and concentration for WWTP (Wastewater Treatment Plant) operations. By floating and concentrating sludge to 30-100% solid content, the DAF2 reduces sludge volume before digestion or dewatering, cutting downstream processing and disposal costs. The upgraded DAF2 design with W-type sludge hopper