EARLY-STAGE CHARACTERISTICS OF BIOLOGICAL TREATMENT BY PUF FLUIDIZED-BED - FOR TREATMENT OF DIALYSIS WASTE-WATER

In dialysis wastewater treatment by a fluidized - bed bioreactor using polyurethane cubes as support particles, substrate consumption and mi crobial growth processes were investigated, focussing on the earlier s tage of the process. Retained microbes were found to initiate growth i nside the particles after sticking from water phase and to form biofil ms after experiencing decay and falling-off. The mass increases very q uickly and reaches a steady value in an unexpectedly short time. Follo wing the growth of retained microbes, the mass of suspended microbes a lso reaches a steady value relatively quickly, recovering from a minim um caused by entrapment by the support particles. These prosesses were shown to be explained well by mass balance equations with the Monod k inetic equation by introducing new terms for sticking and falling - of f processes. Rate coefficients are determined for various influent con ditions.