EMD and VERSA: Rotary Drum Screw-Screen

Typical Applications:

• Pre-treatment of Municipal Wastewater
  
• Solids Recovery and Processing from Industrial Efflients
  
• MBR Membrane Bioreactor Inlet Screening
  
• Storm Overflows and Sea Outfalls

Operating Principle

EMD and VERSA Rotary Drum Screw-Screens are integrated machines consisting of a screen, a screw conveyor and compactor. During operation, solids within the incoming flow will enter into the drum screen and progressively collect onto the screen mesh and cause it to gradually blind. The upstream water level will rise and at a predetermined level, the drum screen and screw conveyor will activate and rotate immersing a clean section of the screen into the effluent.
During rotation the solids or screenings will become inverted and then fall into the screw conveyor. Spray nozzles and a roller brush fixed to the periphery of the drum screen will clean away any residual solids from the mesh. The screenings are conveyed, compacted and dewatered and depending upon the solid properties, a volume reduction of around 40% DS or greater can be achieved prior to disposing the screenings into a skip or wheel bin.
A jet wash facility in the compaction zone will break down and remove faecal and other semi-solid or soluble matter and return it to the inlet flow. Additional jets can be installed in the transport zone to meet higher specifications of organic solids removal. Faecal matter washing efficiencies greater than 90% and screenings weight reduction of 50% can be achieved.
The compactor and wash system can be omitted to suit requirements such as CSO applications where the screenings are returned to the downstream sewer.

EMD and VERSA rotary drum screw-screens can be supplied for direct installation into a channel or as a complete package inside a stainless-steel tank with or without the option of a bypass rake screen. Continuous bagging systems are available to receive screenings and abate odour, the screenings can then be sealed without any personal contact.

Why VERSA over EMD

The necessity was to design one equipment to be installed in each channel and in every condition; for example:

• Absence of lateral channel “bypass”
• Big sizes solids and/or longs fibres present in the effluent
• High solids concentration

Great benefits come from the fact that VERSA rotary drum screw-screen was designed without any bearing and any fix or rotating arms in the lower part of the filtering drum. Screen area is totally free with big advantages not only for the incoming solids, which have no possibility to find any obstacle, but also concerning head loss. In addition, the drum will rotate until that the level before the screen will reduce, instead of only the screw conveyor will continue the rotation lifting up all the solids from the hopper present in the screen zone. These are the reasons because VERSA drum screen is really suitable to be installed in each channel with every kind of effluent.

EMD in a box

EMD/VERSA Operating Principle