1. Fine screening
Depending on the specific conditions and data, such as peak flow, screenings load and grit load, one of the following screens is selected:
- ROTAMAT® Fine Screen Ro 1
Bar spacing 6 or 10 mm
- ROTAMAT® Rotary Drum Fine Screen Ro 2 / RPPS
Bar spacing 1 - 6 mm
- ROTAMAT® Micro Strainer Ro 9
Bar spacing 1 - 6 mm
- HUBER Belt Screen EscaMax®
Perforation 1 - 10 mm
- STEP SCREEN® SSF
Slot width 3 / 6 mm
2. Screenings treatment
- Fine Screen Ro 1 / Rotary Drum Fine Screen Ro 2 / RPPS / Micro Strainer Ro 9
All ROTAMAT® Screens include a screenings press.
Screenings washing with IRGA (optional)
Dewatering and compaction in integrated screenings press
Solids concentration of screenings: Up to 45 % DS.
- STEP SCREEN® SSF, Belt Screen EscaMax®
A separate Screenings Wash Press WAP is usually installed behind a Step Screen®.
Solids concentration of screenings, depending on the WAP type used: Up to 50 % DS.
3. Grit separation
The grit channels of our ROTAMAT® Complete Plants are designed in accordance with international standards or the customer’s specific requirements. The grit channels are available as aerated or optionally unaerated units. The selection of the grit channel type (aerated or unaerated) depends on various criteria, such as the storm/dry weather flow ratio or whether further grit treatment systems are planned.
4. Grit removal and discharge
The settled grit is collected from the bottom of the grit channel with a horizontal grit screw. An inclined grit screw conveys, agitates and dewaters the collected grit. The classified grit slides from the upper end of the inclined screw into a RoSF 4/t Grit Washer.
5. Grease separation and removal (optional)
Separation of fats and grease is only available when used with aerated grit channels. The grease is collected in a separate chamber with the partition between the grit trap chamber and grease chamber consisting of a slotted scum board. In contrast to many competitors, the floating fats and oils are skimmed off the water surface with a paddle scraper that is slowly pulled with a stainless steel rope. The paddle is shaped so that it removes virtually all floating matter from the grease trap. Anaerobic degradation of fat and grease and therefore odour nuisance, is thus prevented.