On-line estimation of Nitrosomonas kinetic parameters in activated sludge samples using titration in-sensor-experiments

A method is presented that uses H+ production of the first nitrification step as an alternative to oxygen consumption to characterise activated sludge nitrification kinetics. The method consists of a titration in-sensor-experiment with nitrifying sludge combined with a parameter estimation procedure. Based on a cumulative base addition curve, it is possible to estimate the volumetric nitrification capacity of the mixed liquor (mu(A) X X-BA/Y-A, in (mg-N/litre)/h) and the Monod half-saturation coefficient K-NH for the Nitrosomonas bacteria in the sludge. It is shown with lab tests and on-line in-sensor-experiments on a pilot activated sludge plant for N removal that the proposed combination of a titration experiment and a parameter estimation procedure can also be used to estimate nitrifiable N concentrations present in a mixed liquor sample. (C) 1998 Elsevier Science Ltd. All rights reserved.