STEADY STATE MODEL TO PREDICT VOLATILE SOLIDS REDUCTION IN ANAEROBIC DIGESTION

A semi-empirical model has been developed to predict the volatile solids reduction (VSR) in the anaerobic digestion process under a variety of operating processes. The model's predictive capability was compared with the performance of 34 full-scale anaerobic digesters divided into 7 technologies. The model predicted well the performance of the plants with the difference between the model responses and the plants performances varying from -1% to +8%. The model's predictive capability was also compared with that of the International Water Association Anaerobic Digestion Model No. 1 (ADM1). The semi-empirical model predicted the VSR in the digestion process at least as well as ADM1 over the range of conditions tested. The input parameters to the semi-empirical model are less complex than those required for ADM1, thus offering process engineers and operators a simpler alternative for predicting VSR reduction in anaerobic digesters. The model was applied to digester technologies with a maximum two stages. Its structure, however, allows it to be applied to digester technologies with more than two stages.