Operating a purification plant with a longitudinally-flowable aerated activated-sludge tank and controlling dissolved oxygen concentration in the tank using a controller, comprises supplying an amount of air to the activated-sludge tank

摘要

The method for operating a purification plant with a longitudinally-flowable aerated activated-sludge tank and for controlling dissolved oxygen concentration in the activated-sludge tank with two sections lying one after another in a flow direction, comprises controlling the dissolved oxygen concentration using a controller of the sections, so that the actual value of the dissolved oxygen concentration is determined, and supplying an amount of air to the activated-sludge tank corresponding to a given desired value of the dissolved oxygen concentration. The method for operating a purification plant with a longitudinally-flowable aerated activated-sludge tank and for controlling dissolved oxygen concentration in the activated-sludge tank with two sections lying one after another in a flow direction, comprises controlling the dissolved oxygen concentration using a controller of the sections, so that the actual value of the dissolved oxygen concentration is determined, and supplying an amount of air to the activated-sludge tank corresponding to a given desired value of the dissolved oxygen concentration. The dissolved oxygen concentration in the activated-sludge tank sections adjusts itself corresponding to the desired value. For each section, a regular supply of air takes place in the activated-sludge tank section according to the relation of Q(LV) = Q(L).SO/SO s a t, where the Q(LV) is the amount of air loss in the section, Q(L) is the amount of air supplied to the section, SO is the dissolved oxygen concentration in the section and SO s a tis the saturation concentration of amount of air loss calculated by the dissolved oxygen. The controller of the dissolved oxygen concentration of the individual section is superimposed to the controller influencing the desired value of the dissolved oxygen concentration. The controller influencing the desired value of the dissolved oxygen concentration effects an amount of air supply in the section, which adjusts itself equal large amount of air loss for all sections. The desired value of the dissolved oxygen concentration in the sections is determined by a given specification.