Biodegradation kinetics of stored wastewater substrates by a mixed microbial culture

The anaerobic accumulation of several organic pollutants from industrial wastewaters, as storage substrates, and their subsequent aerobic biodegradation using a wastewater treatment mixed microbial culture for biological nutrient removal has been studied. The amount and the kinetics of substrate accumulation in the anaerobic stage depended on the characteristics of the wastewater fed to the anaerobic stage. Depending on the substrate used, levels of between 27 and 86% of storage polymers were accumulated with respect to the level obtained on feeding with acetate. The biodegradation kinetics were studied by modelling respirometry results. During the aerobic stage, oxygen-consumption data obtained in the respirometric tests were fitted to a model using a non-linear fitting estimation method. The simulation data obtained correlated well with the experimental oxygen-consumption data. The estimated kinetic parameters obtained indicate that each storage polymer was degraded at a different rate. However, the values obtained for the storage polymer half-saturation coefficient, KS: 16 mg COD l−1, and for the coefficient for endogenous respiration, b: 0.008 h−1, were similar in all the experiments. The results indicate that each substrate produces the synthesis of a specific storage polymer that is degraded at a different rate.