In this scientific research, an empirical model was designed that represents a general method applicable to many substrates, such as the reuse and revaluation of agro-industrial wastes. This model will allow determining the structural properties of a matrix of lignocellulosic material from orange peels, by relating them to the measured values of the pressure drop as a function of the air flow velocity, flowing along a fixed bed of lignocellulosic material, during the solid-state fermentation process, in a cylindrical bioreactor.