Abstract
An algorithm for feedback control of activated sludge waste rate has been developed. It uses proportional-integral-derivative (PID) control with waste flow rate as the manipulated parameter and an unsteady-state calculation of sludge age (the dynamic sludge age, or DSA) as the process variable. PID control can be implemented either on-line using sensors and automatic control, or off-line using lab results and manual implementation of computed control action. Both methods were studied using computer simulation. Feedback control reduced the error in DSA by 60% for a step change in setpoint, and 80% for a step change in influent biochemical oxygen demand (BOD), as compared to no control (constant waste flow rate). For a realistic forcing function consisting of 6 months of influent flow and BOD data, the variability of the DSA was reduced by 22% by continuous PID control, and 14% by off-line control. Improved DSA control resulted in increased variability in system biomass.
Original language | English |
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Pages (from-to) | 1979-1985 |
Number of pages | 7 |
Journal | Journal of the Water Pollution Control Federation |
Volume | 60 |
Issue number | 11 |
State | Published - 1988 |