Among the industries fundamental for modern life, wastewater treatment receives increasing interest for its potential to recuperate valuable resources. The biogas obtained through anaerobic digestion, more specifically, the methane it contains, often represents a powerful asset in operating a WWTP (wastewater treatment plant) economically. However, the microbiological processes that lead to obtaining methane are quite hard to model, and the results might not reflect the situations encountered during operation. One of the ways to estimate the methane yield of the substrate is based heavily on COD and its bioavailability. In this paper, an attempt was made to calibrate a more complex model to a situation where the extensive amount of data, usually required for accurate methane production estimations, is not available. The data obtained from simulations was compared to data obtained experimentally.