Advanced control of anaerobic digestion processes through disturbances monitoring

This paper presents a new control strategy for highly loaded anaerobic dige stion processes. This strategy is based on the analysis of disturbances add ed on purpose to the influent flow rate. The control system then carefully overlooks the response of only two parameters, the biogas output flow rate and the pH, in order to determine whether or not the load can be increased. The main advantages of this approach rely on its capability to automatical ly adapt the input flow rate to changes in the influent concentration, with out any information on its concentration, and to optimize the biological tr eatment in relation to the influent degradability. Experiments have been ca rried out using two fluidized bed reactors of different sizes and they have demonstrated very good capability of this control strategy. In addition, s ince only very simple sensors are needed, industrial applications of this s trategy can be expected. (C) 1999 Elsevier Science Ltd. All rights reserved .