Image Number 2 for United States Patent #6120687.
A vessel (10) for placement on a land site for treatment of wastewater, in which an inlet (22) communicates wastewater, grit, and suspended solids into a grit collecting chamber (24) for settling grit particulates therefrom. An aeration zone (34) receives air from nozzles (37) for facilitating biological digestion of the suspended solids and conversion to activated sludge. The activated sludge communicates through an airlift (70) to a mixing chamber (30) which also receives wastewater with suspended solids from the grit collecting chamber. The air from the nozzles (37) creates an upflow of wastewater and activated sludge to secondary clarifiers (42) having sludge receiving plates (48) on which the sludge settles, accumulates, and falls from, resulting in treated water in the upper portions of the secondary clarifier (42). The treated water discharges in a trough (62) from the vessel (10). A method of sanitary treating of wastewater is disclosed.