| Heterotrophic biofilms growing in the successive three stages of the RBC reactor in a full-scale wastewater treatment plant in the summer of 2002 were investigated and compared to those growing in the fall of 2001. The seasonal changes in their structure were studied in terms of biofilm thickness, dry solid density, internal pore distribution and patterns, and surface roughness.; The comparison results indicate that due to the higher flow rate in the summer of 2002, these biofilms had thinner, denser and less rugged surface structure than the biofilms sampling in the fall of 2001; furthermore, they showed less heterogeneous internal pore distribution. However, biofilms from both seasons showed some similarities: biofilms in stages 2 and 3 had similar structure; and their internal geometric porosity and pore surface roughness didn't show any correlation with the biofilm depth.; A similar study of nitrifying biofilms was not carried out because little biomass grew on the sampling tapes during the summer sampling period. |
