The ROMAG CSO screen RSU consists of a rugged frame made of stainless steel sections. The horizontal rake bars are braced in this frame. The cleaning carriage which is moved to and fro by a double-acting hydraulic cylinder is located on the upper side. Several comb rows of asymmetrical triangular shape move through between the rake bars. The water flowing through forces the caught material against the bars where it is moved on by the cleaning combs with their „steep end“ in longitudinal direction. The flow direction assists this movement. During return travel, the „flat end“ of the combs slides through beneath the caught material. The traverse paths and shapes of the combs are intermatched so that each cleaning comb transfers the caught material to the next cleaning comb. It is slid to the end of the rake and is then discharged with the outflowing effluent to the sewage treatment plant.
This prevents a problematic concentration of caught material at the inlet end.
The CSO screen RSU has proven successful in many applications. However, close cooperation with the offices and agencies involved is necessary in order to achieve a reliably operating installation. This is necessary in order to determine and comply with the hydraulic boundary conditions.
This relates to streamlined feed to the CSO screen and discharge to the sewage treatment plant with the required downgrade: System planning
The caught material which is transported by the rake to a defined point must move continuously downwards into the discharge to the sewage treatment plant. One good solution is to use a caught material shaft.
Particular attention must be paid to the space conditions in the inlet area. Excessively constrained inlet sections aggravate or render impossible the inspection and maintenance work which is required periodically.
Zürich-Wollishofen sewage treatment plant, left basin half, ROMAG CSO screen RSU in the background. The hydraulic pipe for the cylinder is clearly visible. The hydraulic cylinder can just be seen above the edge of the masonry wall.