Microbial filters biofilms

Mack et al (57) studied the development and ecological succession of microbial films in a newly commissioned trickling filter system. A biofilm formed over the rock surfaces and consisted of a micro-jungle of bacterial colonies, fungi, algae and protozoa. 

Due to the adhesion capacity of microbes, biofilm formation must be taken into account in river analysis as well as in the chemostat or fixed beds (percolating or trickling filter). The significance of microbial films in fermenters has been extensively studied and reviewed (Atkinson, 1973, 1974 Atkinson and Fowler, 1974 Atkinson and Knights, 1975 Charaklis, 1981 Harremoes, 1978). 

Heterotrophic bacteria appear in great quantity in the course of water filtration through carbon filters as carbon is an ideal growth medium for these bacteria, which attach to the porous surface of the filter and obtain food by consuming adsorbed water contaminants. Under suitable conditions, they adapt to environment and grow as biofilm. The most suitable conditions for the growth of bacterial colonies occur in the mesoporous activated carbon filters. The substances for microbial consumption are effectively fixed and accumulated within these filters. 

The importance of biofilms in this process can not be overestimated. There are very good reasons to believe that bacteria are not free floating in a paint, but most of them are living in biofilms or are adhered to surfaces of the ingredients and the equipment. Biofilms in production equipment like tank surfaces, water pipes, on sealants, on filters are built easily and quickly within hours. They can not be removed by simple means but can cause consecutive and unpredictable introduction of locally high microbial counts and biological material in the paint. See also chapter 5.1. 

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