KINETIC-BEHAVIOR OF HETEROTROPHIC AND AUTOTROPHIC BIOFILMS IN WASTE-WATER TREATMENT PROCESSES

Conventional laboratory scale annular reactors were employed to invest igate the growth dynamics of both heterotrophic and autotrophic biofil ms. Based on the experimental observations and physiological aspects, which consist of defining two types of biomass: active biomass (Ma) re sponsible for substrate removal, and non-active biomass (Md), which pl ays no role in the biological substrate removal process but is respons ible for the observed additional accumulation of biofilms. The experim ental results showed that the biological constants were strongly depen dent on the influent substrate concentration (So). It was found that t he same was true for the volumic substrate removal rate (kov), which s hows a surface reaction independent of the film thickness, and that su bstrate removal in both heterotrophic and autotrophic biofilm reactors remains reactive. The results demonstrated that thinner biofilms rang ing from 20 to 30 mu m have a higher specific removal rate. It is pref erable to use thin biofilms for attached culture industrial processes such as three-phase fluidized-bed and turbulent reactors. The results showed that it is possible to eliminate very high carbon loadings up t o 10 to 15 kgTOD/m(3)/d in a three-phase fluidised-bed reactor, and pr omising results were obtained for simultaneous removal of carbon and n itrogen in the turbulent bed.