Fuzzy plus integral control of the effluent turbidity in direct filtration

This paper studies the effluent turbidity control of a deep bed rapid sand filter run by direct filtration method. In spite of the highly nonlinear filter dynamics, the maximum filter run time and optimum chemical usage are achieved. The disturbances such as the filter flow rate and the influent (ra...

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Bibliographic Details
Published in:IEEE transactions on control systems technology 2004-01, Vol.12 (1), p.65-74
Main Authors: Onat, M., Dogruel, M.
Format: Article
Language:English
Subjects:
Applied sciences
Chemicals
Computer science
control theory
systems
Control theory. Systems
Effluents
Error correction
Exact sciences and technology
Filtration
Flow rate
Fluid flow measurement
Fuzzy control
Fuzzy logic
Influents
Mathematical model
Mathematical models
Nonlinear dynamics
Nonlinear filters
Pressure measurement
Sand
Studies
Temperature
Turbidity
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Summary:This paper studies the effluent turbidity control of a deep bed rapid sand filter run by direct filtration method. In spite of the highly nonlinear filter dynamics, the maximum filter run time and optimum chemical usage are achieved. The disturbances such as the filter flow rate and the influent (raw water) turbidity that directly affect the effluent turbidity are compensated successfully. The behavior of the filter is determined by on-line measuring of the influent and effluent turbidities, the bed pressure drops, the flow rate, and the temperature of the influent. The required alum is directly dosed into the filter by a dosage pump controlled by the main computer. The extraction of a mathematical model of a sand and polymer based filter is very difficult and many times impossible because of the complex nature of the system. Furthermore the filter dynamics is slightly time-dependent and quite nonlinear, making the use of linear control ineffective. Fuzzy control is proposed as most effective for this application, because of its ability to finely tune the control actions nonlinearly across different turbidity error ranges. An integral controller is added in parallel to the fuzzy controller to enhance the control performance for steady state errors.
ISSN:1063-6536
1558-0865
DOI:10.1109/TCST.2003.821948