Non-invasive and Continuous Monitoring of a Pilot-scale Trickling Filter: Weight, Off- Gas and Hydraulic Characterization

A pilot-scale trickling filter has been constructed in order to collect experimental data on a fully characterized biofilm system for the selection, development, calibration and corroboration of mathematical models which describe such a system’s dynamic behavior. The design of the unit was made such that it allows a full characterization of the relevant model parameters, and an easy monitoring of the system’s performance only using measurements of inflow and outflow. By means of an electronic balance, the weight of the filter unit is continuously monitored. It is shown that information about the filter’s weight can be used to accurately determine biofilm and hydraulic characteristics. Also the off-gas is continuously monitored for CO2 and O2. These measurements allow to establish closed carbon and oxygen mass balances. Several short term experiments are conducted to reveal the possibilities of off-gas analysis to monitor, model and control the filter’s performance. Two tracer tests were conducted on the filter without and with biofilm. NaCl and Thioflavine-S were used as a tracer. The hydraulic behavior of the filter without biofilm could be described using an advection-dispersion model. If a biofilm was present however, a CSBR (continuously stirred biofilm reactor) approach was found to yield an optimal description of the hydraulics.