Ks is the Monod constant and "S" is the concentration of the nutrients (also called as substrate). The rate at which the nutrients are consumed can be written as ds dt dS dS dt ds dt d = [ -d cell maint: + [ - ]cell gen. + [at] prod dt Ts = - =-(msx msX+ r's = - msX + 1 dX Yx/s dt 9pX + YP/S) 1 ("maxS 9pX\ Yx/s Ks+S) X + YP/S Here, T's ms volumetric rate of generation of nutrients (units g/L h) maintenance coefficient (units g nutrients/g cell h) Yx/s-cell yield coefficient (units g cell generated/g nutrients consumed) Yp/s-product yield coefficient (units g product formed/g nutrients consumed) qp :-specific product formation rate (units g product formed/g cell h) 1 dP (qp=x at