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 were quantified by means of a five day intensive measurement campaign with the use of on-line respirometry and on-line off-gas analysis. Respirometry was used to measure the readily biodegradable CODst and the off-gas sensor was used to monitor the O-2 and CO2 content of the off-gases. To model the biodegradation in the filters, the model developed by Rauch et at. (1999) was used. It is based on the decoupling of two basic processes in biofilm systems, 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 measurements revealed that the system was not always oxygen limited. The model calibration thus required the use of a very low value of the diffusion constant for readily biodegradable substrate

Development of a chemical fate model for trickling filters based on the activated sludge model Simple Treat: a case study for LAS

A new chemical fate model for trickling filter wastewater treatment plants was developed, using the same principles as the steady-state nonequilibrium activated sludge model SimpleTreat, in combination with an existing biofilm model. To test the new model in detail, a pilot-scale (200 L) trickling filter was built and operated. Using this setup, removal of the surfactant LAS was measured under different well-characterized operating conditions. The new model could be fitted to data on LAS removal in the pilot-scale filter as well as in two full-scale domestic treatment plants. The same biodegradation rate coefficient (derived from activated sludge data) could be used in all cases, except for one laboratory experiment with higher LAS influent concentrations. It is concluded that the effect of high influent concentrations on the biodegradation rate should be further investigated