The roots of the activated sludge process date back to the early 1900's and the pioneering work carried out at Davyhulme, Manchester which led to the formation of Activated Sludge Ltd. The following are some of the highlights in the development of the diffused aeration technology which is the heart of the activated sludge process.
The first public mention of the word "diffuser""a continuance in the nature of a box, the top surface of which is composed of a specially prepared porous tile. The air was admitted underneath and diffused through the porous tile".
The first commercial diffuser produced from foundry slag and cement. First installations at Worcester and Manchester.
Diffuser design based on plates and tray - the "made-in" type, in ridge and furrow aeration tanks.
Activated Sludge Ltd established with Mr J A Coombs, as Managing Director, Dr G Fowler, co-founder of the activated sludge process, Mr W Jones, owner of Jones & Attwood Ltd.
Removable plate diffusers introduced.
The "Alundum" porous plate comes into general use.
Extensions at Davyhulme STW, Manchester completed (72.5 tcmd).
Complete new activated sludge works at Mogden opened for operation, based on population equivalent of 1,000,000.
Large scale trials of 100 mm diameter dome diffuser began.
Tests at Maple Lodge STW, near London, were begun with a 178 mm diameter dome diffuser.
The 178 mm diameter dome diffuser accepted as industry standard after successful completion of trials at Maple Lodge STW.
Work begins to develop a reliable probe for instantaneous read-out of dissolved oxygen levels in activated sludge plants; the Mackereth electrode results.
Trials begin at Rye Meads STW, Herts with eight Mackareth electrodes at various positions, in a four pass aeration tank; produces 20% power cost savings.
Extensions at Oxford STW include, for the first time: plastic floor pipework, internally coated cast iron bus mains, ultra filtration pre coat air filters, diffusers with 2:1 turndown ratio, variable speed air blowers, linked to D.O. control circuit, tapered floor layout.
Extensions to Beckton STW, London's northern outfall treatment works, to treat a population equivalent of 3,000,000.
Extensions at Norwich, for population equivalent of 110,000, with computer control for the first time.
Extensions at Longreach STW, Dartford, for population equivalent of 1,115,000, bringing pollution relief to the lower reaches of the River Thames.
Refurbishment of Hyde STW, near Manchester (population equivalent 97,000), seeing the FBDA process return to its northern birthplace.
Extensions at Cotton Valley STW, Milton Keynes and the merging of two plants into one, (population equivalent 270,000).The use of anoxic zones now fully developed and understood, reducing nitrate levels in UK rivers.
Introduced membrane disc diffusers.
Installed deeptank aeration in Macau with 8.0 m deep tanks.
Developed an interchangeable diffuser system with flat disc ceramic and membrane disc on interchangeable saddles.
Replacement and extension of the Minworth Activated Sludge Plant for Severn Trent with 122,000 ceramic diffusers.
Introduced membrane tubular diffusers in 0.5-3 m lengths mounted onto fixed or lift out pipe systems.
New e-commerce website providing an on-line spares service and a user friendly design and budget price facility for new FBDA systems.
Market Parker agreement with Environmental Dynamics Incorporated (EDI) with increased product portfolio including 9" membrane/ceramic interchangeable discs and mini panel tubular systems.
Enhancement of global support for enhanced fine bubble aeration with Environmental Dynamics Inc. purchase of the operating assets at Water Engineering Ltd.