Background. When performing technological calculations of water treatment units for thermal power plants (TPP) and nuclear power plants (NPP), it is necessary to determine the quality indicators of process water after the processing steps. The main difficulty is to calculate the concentrations of weak electrolytes since they are in chemical equilibrium with all forms of dissipation. Currently, for each type of processing, either simplified models or methods that solve a complex computational problem are used for calculations. It is necessary to develop a universal mathematical model that allows high accuracy to calculate the concentrations of weak electrolytes and the pH value for various types of water treatment.
Materials and methods. To develop the model the authors have applied the method of mathematical modeling of chemical-technological processes at thermal power plants and nuclear power plants.
Results. A mathematical model based on the transformed equation of electrical neutrality is proposed. It can be used to determine the equilibrium concentrations of dissociation forms of weak electrolytes (primarily water itself and carbonic acid) after various stages of water treatment.
Conclusions. The proposed model allows, when conducting technological calculations of water treatment plants, to more accurately and universally calculate the concentrations of weak electrolytes and determine the pH value in process waters for various types of water treatment. The model can be used to determine the required doses of chemical reagents to ensure the required values of technological indicators (pH and Langelier index) in treated water.