Energy-Efficient Control of a Deacidification

In Uevekoven, Germany, drinking water treatment contains a deacidification step with three separate aeration columns. Physical deacidification is realised in a downword flow of the water over packed columns, with a counterflow of air supplied by an external blower. The amount of carbon dioxide removed can be adjusted via the amount of air supplied by the blower. Frequent changes both in composition and quantity make an automated control system desirable.

To ensure energy efficient control of deacidification, it is vital to measure the lime concentration of the water coming out of the aerator columns; a high precision measurement is required for this type of control. The measurement and control system BalanceCon by Dr. A. Kuntze (Germany) is excellently suited for the task. It measures the pH of the water, while an integrated pump feeds part of the water via a marble filter to a second pH measurement device.

The stepmotor-controlled pump ensures a defined and constant contact time within the marble filter, so that water in the second pH measurement is definitely in a state of calcite equilibrium. Via the difference between the two pH measurements, the deacidification process can be controlled with a very high prescision. Changes between the two sensors are periodically determined by an automated zero calibration of the difference measurement. With the BalanceCon measuring and control system an accuracy of < 0.02 ph can be achieved.