A&J Fabtech has developed an innovative, high performance surface scum removal system for use in activated sludge processes that uses a collector arm to retain scum around the scumbox for effective withdrawal.
Removed continually in small batches, scum presents few problems in settlement tank processes. However, if it is allowed to build up it can become an issue. There are several existing procedures for dealing with scum, although there is room for improvement in them all.
Traditional systems use a scum blade mounted on the rotating bridge to direct the scum into a scum box, which is mounted to at the tank wall.
In the A&J Fabtech system scum is collected by the scum skimming blade and directed towards the scum box, as in the traditional solution above.
The concentrator arm extends towards the centre of the tank and acting to obstruct the scum, retaining it around the scumbox for efficient withdrawal of the scum when the scumbox actuates with the passing of the bridge. The passing bridge pushes the concentrator arm back against tank wall as it passes (by which time the scumbox has fully dipped).
Once the bridge has passed, the mechanism slowly returns the concentrator to its extended position. In use, the arm concentrates the scum with each pass of the rotating bridge, collecting scum at the scum box rather than allowing it to be pushed endlessly around the tank. Thus, the scum is continually collected so that there is no troublesome build up.
Used in conjunction with the dipping scumbox, the scum concentrator arm can be retro-fitted to existing settlement tanks.