An activated sludge tank, 30 x 30 x 200 ft, is designed as a plug-flow reactor, with an influent BOD of 200 mg/L and a flow rate of 1 million gallons per day.
a. If BOD removal is first-order reaction, and the rate constant is 2.5 days^-1, what is the effluent BOD concentration?
b. If the above system operates as a completely mixed reactor, what must its volume be (for the same BOD reaction)?
How much bigger is this, as a percent of the plug-flow volume?
c.If the plug-flow system was constructed and found to have an effluent concentration of 27.6 mg/L, the system could be characterized as a series of completely mixed-flow reactors. How many?