Modelling of the anaerobic reactor in a biological phosphate removal process

A kinetic model called SIPHOR has been developed for the biological phosphate removal process. The model is based on IAWQ Activated Sludge Model No 1, and is divided into three sub-models, one anaerobic, one anoxic and one aerobic model. This paper describes the anaerobic model and results from a calibration and verification of the model on batch experiments performed with sludges from a full-scale plant in Helsingborg and a pilot-scale plant in Malmo. Both plants were run as UCT-processes. Anaerobic batch simulations have been used to identify the following constants, P-release rate (k(p)), fermentation rate (k(ferm)), anaerobic hydrolysis rate (k(hx)), P-release/VFA-storage (f(pp)) and the half-saturation coefficients, K-va and K-pop. The stoichiometric constant f(pp) has been found to be directly related to influent waste water. If acetate is added as carbon source, f(pp) has a value of 0.43, for primary hydrolysed waste water the value is 0.35 and for normal primary waste water, 0.30 in Helsingborg and 0.35 in Malmo. The rate of anaerobic hydrolysis has been found to be near zero in the anaerobic reactor. Copyright (C) 1996 IAWQ.