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IV. Wastewater Treatment Technologies Topic IV. 8. Biological Processes of Wastewater Treatment: Fazes, Kinetics - Monod’s Equations. Basic Fazes of Biological Processes General mechanism of substances micro-biological transfer: Extracellular substrate degradation by external enzymes
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IV. Wastewater Treatment TechnologiesTopic IV. 8. Biological Processes of Wastewater Treatment: Fazes, Kinetics - Monod’s Equations Basic Fazes of Biological Processes General mechanism of substances micro-biological transfer: • Extracellular substrate degradation by external enzymes • Substrate particles attachment at the cells walls • Substrate diffusion into the cells through the cells membranes • Cell metabolism (biochemical transformations) • Metabolism products diffusion out of the cells
Basic Fazes of Biological Processes General mechanism of substances micro-biological transfer: • Substrate necessary composition • Processes of substrate dissimilation (breathing) • Processes of substrate assimilation (cell growth) • Processes of the cells substances dissimilation (endogenous respiration) ;
Basic Fazes of Biological ProcessesBiological Processes Kinetics Biomass Growth Kinetics 1 - lag-faze; 2 - exponential growth faze; 3 - steady-state faze; 4 - endogenous respiration faze
Biological Processes Kinetics Equations of Monod • Rate of biomass growth X - biomass concentration, g/m3 - coefficient of specific biomass growth rate, d-1 kd - coefficient of endogenous respiration, d-1 m - maximal value of the coefficient , d-1 S - substrate concentration, g/m3 Ks - half-saturation constant, g/m3 • Rate of substrate utilisation Y - biomass yeld coefficient, gX/gS
Biological Processes Kinetics Transformations of Monod’s Equations • Substrate utilisation specific rate - U , gS/gX.d • Biomass age - x , d • Biomass growth rate , d-1
Biological Processes Kinetics Kinetic Parameters Use in the Practice • In the bioreactors design t - necessary design hydraulic retention time to achieve S
Biological Processes Kinetics Kinetic Parameters Use in the Practice • In the real process regulation - necessary degree of purification in respect to S S0 - substrate concentration at the influent S - substrate concentration at the effluent and Then , or Therefore, the necessary effluent concentration S can be maintenance by maintenance of the relevant values of U and x. The value of the later can be achieved by the excess biomass regulation.