Abstract
The structure of biofilm is composed of two parts, base and surface films. In the region of base film, molecular diffusion is considered to be distinguishable. On the other hand, the behavior of surface film is influenced by the mechanical behavior of fluid on surface film and by the configuration of the surface of the biofilm. The change in surface roughness of the biofilm formed by acidophilic iron-oxidizing bacteria and iron precipitates and the effects of the surface roughness on substrate removal flux were investigated by continuous and batch experiments. The ratio of profile length to the length of substratum and rms (root mean square) and power spectrum was used as the quantitative index of surface roughness. The two-dimensional simplified biofilm model in which the roughness of surface was apporoximated to the continuous arcs of circles was simulated by finite element method. The simulation indicated that the increased rate of flux of biofilm with rough surface increased as rms increased and approached the increased rate of surface area when rms was large. The evaluation by the si mulation showed the same trend as experimental results qualitatively.
