Sloughing of microbial film in trickling filters

Abstract A well established model for microbial film growth in trickling filters has been used to study the influence of sloughing on the performance characteristics of trickling filters under conditions of constant input. It has been argued that sloughing occurs when the substrate concentration at the support-microbial film interface falls below a critical value. Under these conditions the effluent BOD fluctuates in a fashion similar to that found in filters treating sewage. This is consequence of the time dependent variation of the microbial film thickness throughout the filter. The results obtained lead to suggestions for improved performance and indicate that without proper understanding of the sloughing process, optimal design and operation of trickling filters is unlikely. It also appears that design procedures based upon an average microbial hold-up are inadequate.