Dynamic Real Time Control of the Activated Sludge Process Using Step Feed

Abstract

<p>This study examined at pilot scale the application of dynamic control with a step feed activated sludge process for control of effluent quality. Computer simulation and pilot studies were used to develop a process control strategy involving the Specific Oxygen Utilization Rate (SCOUR). This control was applied using a real-time minicomputer system. Comparisons were made to a single compartment completely-mixed process operated in parallel to the controlled system.</p> <p>The control strategy attempted to maintain SCOUR at a desired setpoint in the final compartment of a three reactor step feed system. Optimal influent contacting patterns were continuously calculated for the first and third compartments to satisfy the control objective. Unique optimization was not possible if the flow distribution was made to three compartments.</p> <p>Using a SCOUR setpoint of 15 mgO₂/g MLSS-h filterable organic carbon effluent data suggested that a reduced effluent variability can be obtained during high loading periods. At low loadings when SCOUR control was limited, no improvement of effluent TOC was obtained.</p> <p>With SCOUR control, consistently higher effluent solids concentrations were observed. High effluent suspended solids concentrations for the controlled system were probably caused by the inefficient oxygen transfer by the diffuser aeration system in the pilot plant.</p>