MODELING OF VOLATILE FATTY-ACIDS DEGRADATION KINETICS AND EVALUATION OF MICROORGANISM ACTIVITY

Particular cases of Monod kinetics (zero order and exponential growth) were used for the description of VFA degradation by acetate and gluco se pregrown inocula measured by Aguilar et al (1995), and kinetic cons tants were evaluated. The equations with inhibition were used for desc ription of the degradation kinetics of VFA mixtures measured by Mawson et al (1991) and by Ozturk (1991). A good agreement between the model and the batch data with synthetic media and molasses pregrown inoculu m was obtained and microorganism activity was evaluated. Using the gen eralized [METHANE] model of anaerobic digestion described earlier the Monod and Haldane kinetics were tested for the experimental data of No ike et al (1985), where mesophilic conversion of acetate was studied i n a continuous-flow reactor under a wide range of acetate-loading valu es. The system failed at high influent acetate concentration because o f pH inhibition for Monod kinetics and of unionized-acetate inhibition for Haldane kinetics. However the model could not describe the change of effluent acetate concentration. To describe that, the corrected Mo nod and Haldane function with changeable half-saturation coefficients was introduced. Copyright (C) 1996 Elsevier Science Ltd.