Transformers for interfacing anaerobic digestion models to pre- and post-treatment processes in a plant-wide modelling context

In view of the growing importance of integrated and plant-wide modelling of wastewater treatment plants, this work reviews, applies and compares two transforming/interfacing methods by connecting anaerobic digestion and activated sludge models. The two methods are systematic approaches to transform state variables of one model to another and vice versa. The theory of the first method was presented before (Vanrolleghem et al., 2005. Wat. Sci. Technol., 52(1–2), 493–500.) as a general approach for interfacing any two models presented by Petersen matrices. The present work is the first application and therefore validation of this general approach. The theory of the second method was specifically developed for connecting ASM1 and ADM1, both standard IWA models. As an illustration, in this work a specific simulation example is presented in which the COST/IWA activated sludge benchmark plant is extended by sludge treatment and digestion facilities.