Fuzzy PID Control Technique On The Biologic Aeration System For Sewage Treatment

The sewage biology treatment process has such some characteristics, such aslarge lag, non-linearity, randomness and multi-variable. Though the conventional PIDcontrol is applied widely to industrial process of the aeration link, some problemsexist still in actual application.Bases on analyzing the principle of the active sullage aeration, the managementsituation of domestic wastewater treatment plants , the traditional control strategy, themeasurement instruments and process control computers, this thesis clarifies thelimitations of the traditional control strategy (PID) on the aeration control link for thewastewater treatment plant, and brings forward two improved strategies for theaeration system control. Firstly, the balance and stabilization of the air flux in theaeration tank should be solved;secondly, the control strategy of the dissolved oxygenshould be solved. The former adopts improved PID control for the aeration air flux ,the latter adopts fuzzy control strategy according to dissolved oxygen for the aerationair flux. This is aimed at avoiding the traditional control dependence on the transferfunction of a complicated object, such as biologic reaction, ensuring the performanceindex on the dissolved oxygen in the aeration tank to be stable, and approximating thegoal fleetly;at the same time, reducing the harm for the regulating valve in aerationtank, due to the frequent operation, saving the consume of the air, and the workerlabour intensity.