Respirometry as a tool for rapid characterization of wastewater and activated sludge

Abstract

A procedure is presented to estimate biokinetic parameters for heterotrophic and autotrophic process models and to estimate wastewater characteristics in the context of the Activated Sludge Models No. 1 and No. 2. The procedure is based on respirometric measurements at low substrate to biomass ratio (S/X). The addition of nitrification inhibitor is avoided by applying a calibrated nitrification model to the respiration rate data resulting from both heterotrophic and autotrophic degradation. Furthermore, a new procedure is developed for simultaneous assessment of decay coefficients for heterotrophic and autotrophic biomass. The results show that, for a given wastewater/sludge combination S/X can be crucial in obtaining reliable parameter estimates: at a very low ratio not all parameters could be identified. A higher ratio caused problems because of nitrification inhibition.