Development and design of a uPVC diffuser pipe system for activated sludge plants

The business of ASL is in providing aeration equipment for the biological oxidation of domestic sewage and suitable trade wastes. Very briefly we provide equipment to aerate tanks from, say, a 2 m cube up to those at major sewage works, the largest of which is 41.0 m wide and 223.0 m long, operating at a water depth of 3.0 ie.; 27,430 m3 capacity (8 in number).

Atmospheric air is filtered, compressed and distributed through pipes over the aeration tank floors being finally passed through an Alundum ceramic dome diffuser to obtain a large number of small bubbles with the object of increasing the surface transferring oxygen to the mixed liquor, this being a mixture of settled, or sometimes crude, sewage and activated sludge.

By maintaining aerobic conditions in the aeration tanks the activated sludge (which is a complex culture of bacteria) can perform its work of flocculation and oxidation of the wastes in sewage.

Since the war dome diffusers mounted on 4 in diameter cast iron pipe have been our company’s standard equipment, each being secured to the pipe by a headed brass bush screwed into a boss on the cast iron pipe, suitably drilled and tapped along its length, generally at 300 mm centres with the pipes themselves being 750 mm apart.
Pipe diameter is standard but dome and pipe centres are varied to suit the requirements of each scheme.