“…The ODE system exhibits dynamics in very different timescales, especially regarding biomass growth and DOT, leading to a very stiff system. Since the dynamics of DOT are usually very fast compared to the other states, they can be expressed in a reduced form as an algebraic equation and thereby reduce the stiffness of the system significantly building a differential‐algebraic system of equations (Duan et al,
2020). Since the actual DOT (
) can be only measured with a first order delay, the measured DOT (
) is also considered as a state variable, taking the response time of the sensor into account.…”