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2. Activated sludge treatment a. What is the main objective of activated sludge treatment of wastewater? (1.e., which constituent of wastewater is targeted for removal?) b. Is treatment in an activated sludge system a physical, chemical, or biological treatment process? c. In activated sludge systems, why is the solids retention time (SRT) greater than the hydraulic retention time (HRT)? d. Does sedimentation alone remove all the BOD? Why or why not?
. e. In an activated sludge treatment system, the BOD concentration decays according to first order kinetics, with a decay constant kBOD = 1.5 h? The flowrate is 1.0x103 m2/d, and the volume of the activated sludge system is 100 m². If the BOD concentration entering the system is 100 mg/L, what is the BOD concentration in the effluent (in mg/L)? You can model the treatment system as a plug flow reactor.