Microbial films were developed in several packed-bed column reactors and flow channel reactors. Among the nine biofilm reactors investigated, a column reactor packed with thin vinyl strings (1.3mm in diameter), comprising about 10% of the column volume, was best in removing glucose, phenol or TOC from synthetic wastewaters.
Ninety percent of glucose (loading of 9.3kg/m³•d) and 75% of TOC (loading of 4.0kg/m³•d) was removed. Toxic wastewater containing phenol was treated successfully with the microbial film reactor when the influent phenol concentration was less than 0.3g/l. More than 90% of phenol was removed from the wastewater containing 0.05g/l of phenol.
Glucose removal by microbial films was at the highest rate at an early phase of film development. It decreased considerably at later phases. The half velocity constant for glucose removal was estimated at 0.5-0.7g/l, which was one order of magnitude higher than that reported with suspended cultures of microorganims. This suggests that diffusional resistance of substrate transfer in the attached microbial films was a rate-limiting factor for purification of the polluted water.