The Role of PHREEQC Model and Sensor Analysis in Chemical Coagulation Processes Supported by Online Sensors

Abstract

Population growth and industrial development have led to an increasing demand for water and wastewater treatment in Turkey and around the world. To ensure sustainable treatment, it is necessary to have real-time control and monitor the system. Therefore, this study aims to reveal the removal mechanism and control of the coagulation process using the PHREEQC modeling software, which has a promising potential for simulating the chemical equilibrium and reactions of water. The sensor effectiveness determined by the model was confirmed by experimental tests in the laboratory. This was done to identify the shortcomings and differences of the model, to understand and develop mechanistic structure. To observe the effects of temperature changes in the treatment, PHREEQC software was run for each of the temperatures (T) 1, 9, and 25.3oC, with the addition of FeCl3. The data obtained from pH, conductivity, temperature, and Eh sensors were evaluated. As a result of the study, it was found that different temperatures affect the solubility of the ions, with higher temperatures leading to increased solubility and conductivity. With increasing temperature, the solubility of oxygen in water decreases, while pH, Cl-, and the precipitate Fe(OH)3 are not affected by the temperature change. In general, the modeling results are in line with the analytical results of the samples taken in the laboratory. This highlights the attractiveness of using online sensors for sustainable wastewater treatment. PHREEQC has produced more reliable results by using actual chemical equilibrium constants as it considers equilibrium conditions and includes the effects of ionic bonds and ion pairs.