INFLUENCE OF DEPTH ON TRICKLING FILTER PERFORMANCE
The mathematic models used for trickling filter design today do not give a correct picture of the influence of depth on the process efficiency. The effect of an increased filter depth is overestimated, resulting in an uneconomical design. The design models used are normally based on a first order reaction equation and the most common model is the modified Velz equation. In this, the removal rate coefficient is assumed to vary only with temperature (for a given wastewater and filter medium). However, it has been clearly demonstrated that the removal rate coefficient varies with the concentration of dissolved organic matter (and thus with filter depth). Unless this variation is considered, false information will be obtained when the models are used. By using data from a pilot trickling filter it was shown that the removal rate coefficient was strongly affected by the concentration of dissolved BOD at concentrations up to 50-70 mg/L. “Complete abstract not presented.”