Front Line Defence

The sewage works inlet and the initial removal of screenings must be considered the front line of the sewage treatment process. If the initial screening and removal of debris from the incoming flow is successfully accomplished then the downstream operations and treatment of the influent can be successfully achieved.  

Time and again we see sewage treatment works where no coarse screenings exists to intercept bulk debris and the flotsam and jetsam which makes its way into the sewerage network.

Initial coarse screening, especially on large works with gravity feed should be considered an essential element to provide a barrier to damage. In addition, a coarse screen with a nominal 25mm bar gap somewhere in the region of 20% of the incoming screenings would be expected to be removed, reducing load on the downstream fine screens.

SPIRAC has two main coarse screen selections to offer. CHAINGUARDTM our multi-raked bar screen and The RAKEGUARD our single articulated rake screen. Depending on channel dimensions and expected incoming screenings and debris loads we can advise the optimum solution for your treatment works inlet.

With the initial interception of influent successfully achieved with a coarse bar screen, we can turn out attention to fine screening.

SPIRAC again have two main fine screenings solutions. BANDGUARDTM and FINEGUARDTM can offer 2D screenings of sewage flows down to 3mm. 

The BANDGUARDTM, vertical band screen can be supplied in a range of sizes to accommodate civil structure limitations and flow requirements. With Ultra High Molecular Weight Polyethylene panels the BANDGUARDTM offers a robust screenings solution.

The FINEGUARDTM, inclined screen has a number of features to maximise screenings removal. Asymmetric stainless steel screening panels offer the benefit of a step to help retain debris and eliminate rag rolling in front of the screen. The panel profile and self adjusting rotary brush mechanism maximises primary debris removal, while panels are finally cleaned with wash water spray nozzles to complete the cleaning process. 

SPIRAC fine screen designs incorporate cranked link chains which enable the screens to be supplied with odd numbers of panels, more accurately achieving the required discharge height and dispenses with a number of small screen assembly items. This simplifies production and future on site repairs and this way maximising screen availability.

As suppliers of screw (spiral) conveyors and screenings handling systemsfor many years, the addition of a range of screens to the SPIRAC Catalogue means there are no third party interfaces. Equipment selection can be optimised so all elements work together to provide a total inlet solution.