3.2.Biological reaction rate models Volumetric reaction rate,r(kg m-3 h-1) r=gX Where q is a certain specific rate(kg kg) X is the concentration of the biocatalyst(kg m3) The specific(q)and volumetric(r)reaction rates are further specified by subscripts 4s and rs A limiting substrate qs2 and rs2 A non-limiting substrate qo and ro oxygen gp and rp product gx (mostly written u)and rx biomassVolumetric reaction rate, r (kg m-3 h-1) Where q is a certain specific rate (kg kg-1 h -1 ) X is the concentration of the biocatalyst (kg m-3 ) qs and rs A limiting substrate qs2 and rs2 A non-limiting substrate qo and ro oxygen qp and rp product qx (mostly written μ) and rx biomass 3.2. Biological reaction rate models r=qX The specific (q) and volumetric (r) reaction rates are further specified by subscripts