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Oxygen control in a wastewater treatment plant using adaptive predictive controllers Gregor Kandare, Jozef Stefan Institute, Slovenia
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Adaptive predictive control
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Process description 6 pools with butterfly valves and 2 dissolved oxygen sensors each. 4 blowers with diffuser for pressure control.
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Process description
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Control issues Biological dynamics of the process Aleatory operation context Lack of process information Interactive nature of the process
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Control objectives Maintain the dissolved oxygen signal at its setpoint by manipulationg the aeration with butterfly valves. Maintain the air pressure in the main air conduct at a setpoint that minimises energy consumption and assures good oxygen control.
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Control strategy 6 controllers – one for each pool
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PID control Oxygen and valve opening
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PID control Air pressure and airflow
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Adaptive predictive control Oxygen and valve opening
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Adaptive predictive control Air pressure and airflow
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Oxygen control evaluation Reactor PIDAP Factor 10.39740.18632.13 20.66320.25282.62 50.52210.14323.65 60.91380.1516.05
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Energy optimisation Objectives: Maintain air pressure at a minimal level which still permits satisfactory oxygen control. Maintain dissolved oxygen setpoints at a minimal level that ensures required effluent water quality.
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Pressure optimisation
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Change PID – adaptive predictive
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Energy consumption estimation W – energy, p – pressure, V - volume P – power, Φ V - airflowW – consumed energy in each pool in a time interval [t 0,t 1 ]
![Energy consumption estimation W – energy, p – pressure, V - volume P – power, Φ V - airflowW – consumed energy in each pool in a time interval [t 0,t 1 ]](http://images.slideplayer.com/15/4627920/slides/slide_20.jpg "Energy consumption estimation W – energy, p – pressure, V - volume P – power, Φ V - airflowW – consumed energy in each pool in a time interval [t 0,t 1 ]")
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Consumption reduction Pool Average power consumed with PID control Average power consumed with AP control with pressure optimisation Average energy savings [%] Pool 1 51.3642.25 17.74 Pool 2 61.5534.97 43.18 Pool 5 67.6352.28 22.70 Pool 6 54.4741.98 22.93 Total 235.01171.489 27.03
![Consumption reduction Pool Average power consumed with PID control Average power consumed with AP control with pressure optimisation Average energy savings [%] Pool Pool Pool Pool Total](http://images.slideplayer.com/15/4627920/slides/slide_21.jpg "Consumption reduction Pool Average power consumed with PID control Average power consumed with AP control with pressure optimisation Average energy savings [%] Pool Pool Pool Pool Total")
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Conclusions The adaptive predictive controllers stabilise the process and maintain oxygens at therir setpoints More stable oxygen control and pressure setpoint optimisation decrease energy consumption by 15-23 %
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