Process and aeration tank system for biologically treating sewage

摘要

A sewage disposal for biologically treating the same, comprises aerating one portion of the incoming sewage under a relatively strong aeration condition and another portion thereof under a relatively weak aeration condition, so as to produce a relatively aerobic sludge in the first-mentioned portion of the sewage and a relatively anaerobic sludge in the second- mentioned portion thereof, and admixing the two different types of sludges to produce a secondary sludge for collection or removal.