RoS 3Q Screw Presses have become a well established solution for sewage sludge dewatering. The number of new customers for these high-torque machines still doubles every year. The maximum throughput capacity of previously 150 kg solids per hour has made it interesting to use of screw presses mainly for plants with a connection size smaller 30 000 PE.
But when we intensively tested the press with bigger plants and could deliver excellent test results, a strong interest arose on significantly bigger WWTPs as well. Meanwhile, even plant sizes bigger 100 000 PE are equipped with multiple-line installations consisting of ’small’ RoS 3Q units.
To meet the high demand, we have added to this successful series the new RoS 3Q 800 model. The figure ‘800’ stands for the screen basket inside diameter in mm. With a nominal throughput of 450 kgDR/hr or 12 m³/h applications of up to 100 000 PE can now be served with one line.
The RoS 3Q 800 has for example achieved the following results when dewatering digested sludge:
- Throughput: 12 m³/h
- Inlet DR: 4.1 %
- Outlet DR: 25.4 %
- Polymer consumption: 10 gWG/kgDS
- Separation degree: 98.2 %
RoS 3Q 800 test setup – digested sludge dewatering
With these performance data the RoS 3Q 800 directly competes with centrifuges of 350 – 400 mm drum diameter. Beside marginal maintenance costs compared to centrifuges, the decisive advantage of screw presses over their fast running ‘competitors’ is their by factor 7 lower connected load. The Screw Press can be operated with only 3 kW, whereas centrifuges need approximately 22 kW to drive the rotor and drum. Assuming 5000 annual operating hours, the Screw Press achieves savings of approximately 10,000 EUR in operating costs on the electricity bill alone.
Another major operating costs item are the costs for wear-related maintenance and repair of equipment. The degree of wear mainly depends on rotation and relative velocities in the machine. Also in this respect, the Screw Press gains considerable advantages due to its slow rotary speed. While the shaft of the Screw Press performs a maximum of 300 000 rotations, a comparable centrifuge performs 1.05 billion rotations.
The RoS 3Q 800 offers a solution that reliably reduces operating costs also on plants designed for up to 100 000 PE.