Question

For the completely mixed activated sludge process shown below, the system boundary is shown by the dash line. Q is the wastewater flow rate into the aeration tank; Qu is the flow rate of liquid containing microorganisms to be wasted; X. is the microorganism concentration (VSS) entering the aeration tank; X is the microorganism concentration (MLVSS) in the aeration tank; Xe is the microorganism concentration (VSS) in the effluent from secondary settling tank; &c is the microorganism (VSS) in sludge being wasted. Aeration tank Secondary settling tank Q, S. X, S, V (Q+ Qx) X, S (Q-Qw), S, X. Qr, X., S Return sludge lw, X, S Given the soluble BODs in aeration tank and effluent (S) and maximum growth rate constant (um), and consider no decay of microorganisms, derive the expression for the reactor volume (V) step by step starting from the mass balance equation (for microorganisms): Change in Storage = Mass In - Mass Out

Answer 1

fate og slucage flow in the lank dy Aeratonk secondary tank Q ter X, &,v 0,80 (Q - ow) &, xe Go, Xr, s Return eludge Qwxri Ichange in etorrige نه دلم Moss aut Pacation Period OT HRT A x 24 ho) voleme of the tank x adopted food to Micro argenum Ratios It is an importanch organic loading xede for an octivated sludge process, Daily BOD load appled to the aeration sypth es gm Total microbial mas in the syston san Flmocha 50 F/M satora VX+ epeatic

Massin Mass out. =(wax) Moss of poled in the reactory = V XML se Mert Map of suspended sole! Maso out Mass of solid removed with the wasted sludge per day + mass of soled senored with effluent per day [[@w X Xolot (Q-Ow) Vien Oc= sludge aga Moss of suspended soleds (ML. 88) in the syslen (m) Mass of scle leaving the system ker day equation eagh 0 4 6 we get Vix 9. [ 6X + + (-) Xe Ow Xxt ©- Sw) x pa - X Ir Que Xz + Q-Ow) xe Reaction wline v ips variables On