Dynamic modelling and simulation of activated sludge process using orthogonal collocation approach

This paper deals with the improvement in modelling of the dynamics of activ ated sludge wastewater treatment process using a distributed parameter appr oach. A computational algorithm, based on the global orthogonal collocation technique, for the activated sludge process is developed in this work. Ste ady-state and dynamic simulations are performed based on this algorithm. Th e system configuration considers backmixing or intermixing, which can repre sent the actual process more accurately than the idealised flow schemes com monly employed for the design and modelling of the activated sludge reactor s. Based on a dispersed plug how model for activated sludge bioreactor form ulated in this work, a Peclet number in the order of 0.5 to 5 and 5 to 7 in ternal collocation-points are recommended for modelling channel-type activa ted sludge bioreactor. The dynamics of substrate is predicted well whereas the prediction for biomass is fair, when compared to the experimental data. It is also demonstrated in this paper that the proposed algorithm can give superior prediction of process dynamics than the commonly-used tanks-in-se ries technique. Dynamic responses caused by disturbances in the influent wa stewater which propagates at Various spatial positions along the bioreactor can be correctly predicted through simulations. (C) 1998 Elsevier Science Ltd. All rights reserved.