suspended growth cultures general principles

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Treatment using activated sludge comprises the following steps fundamental:

  • a reactor in which the micro-organisms responsible for purification are maintained in suspension and aerated;
  • a solid-liquid separation carried out by a secondary settling tank (or clarifier) a membrane. In a SBR-type process, separation is carried out in the main reactor;
  • a mechanism for recirculating the sludge to the reactor.

In most instances, the activated sludge process is combined with physical or chemical processes used in the pre-treatment and primary treatment of wastewater, and often in a post-treatment stage comprising disinfection and, if necessary, filtration.

Parameters applicable to activated sludge were discussed in suspended growth (activated sludge) process. Table 1 summarises biological reactor classification according to loading and performance.

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Table 1. Activated sludge reactor classification based on loading and performance in UWW