Huber Technology RoDisc secondary disc filter

The Huber Technology RoDisc secondary disc filter, sometimes known as a rotary mesh screen, provides efficient secondary filtering of clarified effluent for municipal and industry applications.

The filter has been designed for fine screening of up to 1500 m³/h with a mesh size down as small as 10 µm.

The filter is used for: separation of fine suspended material (sludge flocks) after secondary clarification; preliminary filtration in drinking water recovery from surface waters and UV disinfection applications; and advanced phosphate reduction through precipitation and flocculation.

With a small space requirement and modular design, the secondary disc filter can be tailored to meet any specific site requirements.

The filter works on the basis of the drum filter principle. The screen consists of horizontally arranged rotating filter discs, each covered with square mesh, installed on a central shaft.

The rotating discs are submerged by up to 60%. Wastewater to be treated flows through the segments from inside to outside and the filtrate is discharged at the inlet end of the screen.

During the filtration process, the filter discs remain in rest position. The solids settle by gravity on the disc surfaces, leading to gradual blinding of the square mesh by the retained solids and resulting in an increasing pressure differential.

When the predefined maximum pressure differential is reached, the solids are removed from the filter surfaces by the slow rotation of the filter discs, combined with a spray nozzle bar.

The removed solids are washed into a trough prior to being discharged. The filtration process runs continuously while the filter discs are being cleaned.

Benefits include: reduced wastewater discharges and reduction of filterable solids; effluent polishing; compact design maximising filtration area to footprint area; can be designed for future works enlargement by adding discs; and high hydraulic throughput capacity.