The empirical Monod equation is
where:
: μ is the growth rate of a considered microorganism,
: μ is the maximum growth rate of this microorganism,
: [S] is the concentration of the limiting substrate S for growth,
: K is the "half-velocity constant"—the value of [S] when μ/μ = 0.5.
μ and K are empirical (experimental) coefficients to the Monod equation. They will differ between microorganism species and will also depend on the ambient environmental conditions, e.g., on the temperature, on the pH of the solution, and on the composition of the culture medium.