In order to develop of support media for biofilm reactor, physicochemical properties and attachability of surface of activated carbon, clay mineral, non-clay mineral, and waste mold sand were examined. Measured physicochemical properties of materials were surface roughness, mean particle size, surface area, hydrophobicity, and surface charge. At a tested materials, activated carbon was the best attachable material and microorganisms were attached 20.1 × 10^7 CFU/㎠ at surface, compared with diatomaceous earth which were attached of 9.2 × 10^7 CFU/㎠. In our research, surface area and hydrophobicity showed more influence than any other factor on attachment of microorganisms.

The objective of this study was to examine the transient response to hydraulic shocks in an inverse fluidized bed biofilm reactor(IFBBR) for the treatment of apartment sewage. The hydraulic shock experiments, when the system were reached at steady state with each HRT 12, 7, and 4hr, were conducted by changing twice HRT per day during 3days. The SCOD, SS, DO, and pH of the effluent stream were increased with hydraulic shock, but easily recovered to the steady state of pre-hydraulic shock condition. In spite of hydraulic shock, there were not much variation of biomass concentration, biofilm thickness, and biofilm dry density.

An inverse fluidized-bed biofilm reactor (IFBBR) was used for the treatment of highly-emulsified oily wastewater. When the concentration of biomass which was cultivated in the synthetic wastewater reached to 6000㎎/L, the oily wastewater was employed to the reactor with a input COD concentration range of 50㎎/L to 1900㎎/L. Virtually the IFBBR showed a high stability during the long operation period although some fluctuation was observed. The COD removal efficiency was maintained over 90% under the condition that organic loading rate should be controlled under the value of 1.5 ㎏COD/㎥/day, and F/M ratio is 1.0㎏COD/㎏VSS/day at 22℃ and HRT of 12 hrs. As increasing organic loading rates, the biomass concentration was decreased steadily with decreasing of biofilm dry density rather than biofilm thickness. Based on the experimental results, It was suggested that the decrease in biofilm dry density was caused by a loss of biomass inside the biofilm.