Monitoring and modelling an industrial trickling filter using on-line off-gas analysi and respirometry

The process characteristics of an industrial scale trickling filter plant w ere quantified by means of a five day intensive measurement campaign with t he use of on-line respirometry and on-line off-gas analysis. Respirometry w as used to measure the readily biodegradable CODst and the off-gas sensor w as used to monitor the O-2 and CO2 content of the off-gases. To model the b iodegradation in the filters, the model developed by Rauch et at. (1999) wa s used. It is based on the decoupling of two basic processes in biofilm sys tems, substrate diffusion and biodegradation. This model was extended with equations for the production and the pH-dependent liquid-phase equilibrium for inorganic carbon (IC). The measured effluent and off-gas concentrations could be followed very closely by the calibrated model. O-2 and CO2 measur ements revealed that the system was not always oxygen limited. The model ca libration thus required the use of a very low value of the diffusion consta nt for readily biodegradable substrate.