Since the moving rings continuously comb gaps in the de-watering drum throughout thickening and de-watering process, clogging is avoided and therefore cleansing water is not required.
Solid substances separated in the de-watering process are also combed out and are automatically washed away using a times controlled-shower. The solids flow back into sludge tank,returned to the thickening and de-watering process.
The inner pressure increase further as the end plate block the flow.This encourages further de-watering of the sludge cake zone. The gap between the rings and screw pitch gradually narrow , thereby , increasing pressure and encouraging the de-watering process .