A constant-depth laboratory model film fermentor

A laboratory model constant-depth film fermentor was developed. Film grew on the surface of polytetrafluoroethylene (PTFE) plugs and was limited to a predetermined depth by mechanically removing excess film. Six film-forming organisms were isolated from river water and used to assess the operating characteristics of the fermentor. Film accumulation was logarithmic, and a steady state was maintained. Electron micrographs show early film development. The fermentor enables film to be grown on any substratum and allows discrete, reproducible, and representative samples to be taken.