CSO Technik’s pump action screen has recently proven the effective operation of its cleaning system by removing three months of accumulated debris on the flow side of the screening basket.
The screen at a combined storm overflow at Godre’ graig CSO South Wales was installed by CSO Technik in October 2008. Unfortunately a power supply to the screen could not be secured until February 2009. In the meantime, the pump action screen was effectively used as static screen to protect the overflow to the river.
When the pump action screen came to be commissioned in mid-February 2009, the screen basket was, as expected, significantly blinded by sewage-related debris. With the power supply secured, the submersible pump that is used to provide the motive power for the screen cleaning system became usable.
The pump is mounted in line with the screen basket and draws storm water from the continuation flow, which is then mixed with air from a venturi injector. The mixed water and air is used to scour the underside of the screening basket to remove screenings and then utilises the motive power of the scouring jet to push the screenings well past the end of the screen and back into the continuation flow to avoid re-presentation.
The pump is the only moving part on the entire screen and as at Godre’ graig is normally mounted on a guide rail system so that it can be removed, serviced and replaced without the need for any hazardous man entry. Consequently, there is no need for any confined entry to service or maintain the screen and field servicing can be carried out by just one man leading to significant operational savings.
The pump action screen supplied at Godre’ graig was designed to handle a spill flow of 90l/s through its 6mm perforated stainless-steel screen basket. The screen was tested at the national CSO testing centre in Wigan and achieved a screenings retention value (SRV) of 58%.
The pump action screen was invented, developed and patented by CSO Technik and is now in service in more than eight countries.