A continuous flow completely mixed reactor $($CFCMR$)$ without solids recycle

has a biomass concentration of $140$ mg MLSS$/$L is used to reduce the

concentration of the organic matter from $300$ to $30$mgBO$\frac{D_3}{L}($soluble$).$

What is the hydraulic detention time needed to achieve this goal? The

following data is given:

$Y=0\mathrm{.}53\frac{mgMLSS}{mgBO{D}_5},K_d=0\mathrm{.}06d^{-1}$

What is observed biomass yield?