The operation of anaerobic digestion (AD) has a strong dependence on reliable information about the state variables and kinetic parameters. Such a dependence can lead the AD to restrictions for the implementation of advanced monitoring and automatic control schemes; with consequent implications at operation decisions. An adaptive observer is proposed to advise on organic matter degradation via AD. The underlying idea is to provide a scheme for monitoring simultaneously both the biomass concentration and parameter related to the maximum growth rates. The proposed scheme is based on a dynamical model of two steps wastewater digester which can be written as a general cascade system. The adaptive observer is experimentally evaluated in a pilot-scale anaerobic digester, which is used for the winery wastewater treatment. As a proof-of-principle implementation, the pilot-scale digester is operated under dilution rate with (arbitrary) bounded time-variation. The results show that the proposed estimation approach can provide a reliable information towards the monitoring and full-automation of AD processes. (C) 2015 Elsevier B.V. All rights reserved.