Screen Assembly for Combined Sewer Overflow Weir

摘要

A screen 12 for a combined sewer overflow weir is in the shape of a cylinder, a longitudinal section of which has been removed, so that the screen is of arcuate form in lateral section. The concave surface of the screen faces downwardly and is traversed by a rotating helical sweeper 20. The screen is preferably semicylindrical as shown, and supported via flanges 14 above a foul water flow. If the water level rises as a result of a storm, water and small solids can pass upwardly through the screen and are carried away to a watercourse over the adjacent weir 24. Large solids including plastics are stopped by the screen and fall back under gravity into the foul water flow. The screen may be made from stainless steel with a non-stick coating, with perforations of 6mm. The helical sweeper 20 has a continuous brush 22 of nylon bristles along its helical edge and is electrically or hydraulically powered. Detritus stopped by the screen is conveyed by the sweeper into a launder chamber downstream of the screen to reduce the clogging effect.