Lockett found that the sludge played an important part The basic activated-sludge treatment process, as illustrated on fig. 7-la and b consists of the following three basic components:(1) a reactor in which the microorganisms responsible for treatment are kept in suspension and aerated:(2 liquid-solids separation, usually in a sedimentation tank; and 3) a recycle system for returning solids removed from the liquid-solids separation unit back to the reactorLockett found that the sludge played an important part. The basic activated-sludge treatment process, as illustrated on Fig. 7-la and b, consists of the following three basic components: (1) a reactor in which the microorganisms responsible for treatment are kept in suspension and aerated; (2) liquid-solids separation, usually in a sedimentation tank; and (3) a recycle system for returning solids removed from the liquid-solids separation unit back to the reactor