Kinetics and Effects of Hydraulic Residence Time and Biomass Concentration on Removal of Organic Pollutants in a Continuous Unsteady State Activated Sludge Process

M. C. Márquez, C. Costa and M. Jul

Abstract
Activated sludge processes are generally affected by the variation of influent flow leading to a modification in biomass concentration and COD removal efficiency. This unsteady state situation can be mathematically explained by a Monod–type kinetics transformed using γSo / γX (influent substrate to reactor biomass ratio) as a control parameter. The kinetic equation has been applied to experimental data obtained in an activated sludge lab plant (5.5 L) using synthetic wastewater (γCOD = 2200 ± 300 mg L–1). Organic load has been modified by increasing gradually influent flow in order to attain different hydraulic residence times (t = 10 to 45 h), leading to optimum values of biomass concentration (γX = 450 to 3200 mg L–1) for maximum COD removal. The application of this type of kinetics that explains experimental results on substrate utilization rate under unsteady state conditions is discussed.

This work is licensed under a Creative Commons Attribution 4.0 International License

Keywords
wastewater treatment, activated sludge, unsteady state, γSo / γX ratio