A complete mix activated sludge plant operates at design Q, with the reactor tank volume set by a nominal= 6 hours..
a) It was anticipated that it would operate at 25% RAS for an expected Xr= 2,000 mg/l. What would the actual be?
b) The secondary clarifier only produces Xr= 1,000 mg/l, so RAS is increased to 50% Q. What is the actual then? Does the F/M, the MLVSS concentration and SRT change?
c) The secondary clarifier actually produces 3,000 mg/l Xr, but RAS stays at 25% as originally planned. Do F/M, MLVSS and SRT change from what was planned?