Optimal Operation of a Two-stage High-rate Anaerobic Wastewater Treatment System: Prediction and Validation

An improved version of a structured model of the anaerobic degradation process, incorporating dynamic equations for the description of a two-stage high-rate anaerobic wastewater treatment system was verified by comparing its predictions with experimental data. Implemented in a recently developed simulation package NIMBUS (CAPE Centre, The University of Queensland, Australia, 1991), the model was able to describe the overall performance of a two-stage anaerobic treatment process as a function of the extent of recycle of the effluent from the methanogenic reactor to the acidification reactor. The results showed that the introduction of recycle could minimise the total operational costs of treatment due mainly to a considerable saving in alkali addition. The effects of the recycle rate on other operating variables such as effluent pH and organic acids, gas generation rates and its composition were also successfully predicted.