ABSTRACT
Microbiological activity transforms pollutants to harmless products in biofilters. Biofilters are inevitably biologically open systems. Phagocytosis is certainly important in the microbial ecology of biofilters because it is used by predators in the food chain. The complexity of the ecology of biofilms is illustrated by discussion of the abundance of fungi in their biotrickling filter. Biofilters succeed (with the one exception of cometabolism) because there is a community of microorganisms present which use the contaminant as food, or substrate. It is commonly observed that microorganisms exposed to a new substrate may require a period of acclimation before they begin vigorous degradation. The bulk of contaminants consumed by microorganisms in biofilters is likely taken into the cells in the dissolved form. The species which are present, their population densities, the metabolic transformations they are catalyzing, and their interactions with their environment and each other are fundamental to biofilter operation.
