Carbon and nitrogen removing activated sludge system will be designed for the city for which

primary settling effluent characteristics are given below.

a$)$ Make necessary assumptions and calculate the minimum aerobic and total sludge ages

required for a nitrification$-$denitrification system, denitrification potential of the system and

effluent total nitrogen concentration $({}_g=0\mathrm{.}80).$ Calculate the required internal recirculation rate.

b$)$ Calculate the anoxic and aerobic reactor volumes using the sludge data given below.

$\frac{1}{{}_{xA,\text{m}\text{i}\text{n}}}=$hat$({)}_A*\frac{N_e}{K_N+N_e}*\frac{DO}{K_O+DO}-b_A,{}_x=\frac{{}_{xA}}{1-\frac{V_D}{V}},Y_{NH}=\frac{Y_H*(1+f_E*b_H*{}_x)}{1+b_H*{}_x}$

${}_x=\frac{V_T*x}{P_{xT}}$

$N_{DP}={}_g*\frac{V_D}{{?}_V}*\frac{(1-Y_{NH})}{2\mathrm{.}86}*C_S,N_x=i_{xB}*Y_{NH}*C_S$