Abstract
Factors affecting the BOD removal rate in the aerated biofilter were extensively investigated. The concept of clogging factor was originally introduced to represent the effect of clogging on the reduction of effective surface area of biofilm for BOD removal in the biofilter. The clogging factor can be used both to select the optimal packing material and to estimate the BOD removal rate in the biofilter with a given packing material.
It was ascertained that a smaller packing material increases the accumulation rate of microbes in the biofilter while it reduces the effective surface area of microbial film for BOD removal due to the excessively accumulated microbes. The microbial concentration in the biofilter with larger packing materials could be maitained low due to the elutriation of excess microbes.
