suspended growth cultures

Several reasons have caused the number of processes termed activated sludge processes or similar as well as biological reactor configurations to undergo changes since they were originally designed: the need for a more advanced quality of water, an in-depth knowledge of microbiological processes, technological advances in the field of equipment, instrumentation and programmable logic controllers, the need to reduce investment and operating costs.

Consequently, various reactor designs have emerged since the inception of activated sludge processes: plug-flow tank, complete-mix tank, oxidation ditch, sequential biological reactor ( SBR ), Membrane Bioreactor ( MBR ) multiple stage systems, especially in connection with nitrogen and phosphorous removal.

These various processes together with the elements required for their utilisation (aeration system, sludge clarification and recirculation …) will be examined and discussed in the following paragraphs.