A waste water treatment system comprising; at least a first primary settling tank (10; A) and a second primary settling tank (10; B) configured to carry out the processes of grit removal, sludge removal, primary clarification, and fine screening, the primary settling tanks (10; A, B) in operation having a waste water level which changes over time between a high level near the top of the primary settling tanks (10; A, B) and a low level near the bottom of the primary settling tanks (10; A, B); each primary settling tank (10; A, B) having a fine screen box which moves in vertical location, between a low level nearer the bottom of the primary settling tank (10; A, B) and a high level nearer the top of the primary settling tank (10; A, B); the fine screen boxes include a water outlet for removal of screened waste water from within the fine screen boxes, the fine screen boxes having fine screen material, the fine screen material having openings of a first size; each primary settling tank (10; A, B) having a bar screen having screen openings of a second size larger than the openings of the first size, the bar screen located in an influent feed trough with a bottom of the bar screen being lower than an elevation of a weir in the influent feed trough, each primary settling tank (10; A, B) having a water inlet for introducing waste water to the primary settling tank (10; A, B), the waste water containing scum and floatables, each primary settling tank (10; A, B) having a water inlet area separated from an interior portion by the bar screen, each primary settling tank having a scum and floatables trough on a side of the bar screen opposite the water inlet for collecting scum and floatables which pass through and over a top edge of the bar screen, the scum and floatables troughs of the first primary settling tank (10; A), and of the second primary settling tank (10; B) are in fluid communication with one another and separated by a scum valve such that when the scum valve is open, scum, floatables and water in the scum and floatables trough flow from the scum and floatables trough of the first primary settling tank (10; A, B) to the scum and floatables trough of the second primary settling tank (10; A, B), each scum and floatables trough having a collection container (54; 154) for collecting the scum and floatables that flow through the scum and floatables trough. at least a first primary settling tank (10; A) and a second primary settling tank (10; B) configured to carry out the processes of grit removal, sludge removal, primary clarification, and fine screening, the primary settling tanks (10; A, B) in operation having a waste water level which changes over time between a high level near the top of the primary settling tanks (10; A, B) and a low level near the bottom of the primary settling tanks (10; A, B); each primary settling tank (10; A, B) having a fine screen box which moves in vertical location, between a low level nearer the bottom of the primary settling tank (10; A, B) and a high level nearer the top of the primary settling tank (10; A, B); the fine screen boxes include a water outlet for removal of screened waste water from within the fine screen boxes, the fine screen boxes having fine screen material, the fine screen material having openings of a first size; each primary settling tank (10; A, B) having a bar screen having screen openings of a second size larger than the openings of the first size, the bar screen located in an influent feed trough with a bottom of the bar screen being lower than an elevation of a weir in the influent feed trough, each primary settling tank (10; A, B) having a water inlet for introducing waste water to the primary settling tank (10; A, B), the waste water containing scum and floatables, each primary settling tank (10; A, B) having a water inlet area separated from an interior portion by the bar screen, each primary settling tank having a scum and floatables trough on a side of the bar screen opposite the water inlet for collecting scum and floatables which pass through and over a top edge of the bar screen, the scum and floatables troughs of the first primary settling tank (10; A), and of the second primary settling tank (10; B) are in fluid communication with one another and separated by a scum valve such that when the scum valve is open, scum, floatables and water in the scum and floatables trough flow from the scum and floatables trough of the first primary settling tank (10; A, B) to the scum and floatables trough of the second primary settling tank (10; A, B), each scum and floatables trough having a collection container (54; 154) for collecting the scum and floatables that flow through the scum and floatables trough.