Using Microwave Energy for the Removal of Hardness from Groundwater: Continuous Flow Lab-Scale System

The present study investigates the characteristics of calcium hardness removal from water using a continuous flow microwave (MW) radiation system with heat exchange. The effects of initial calcium concentration, detention time, and initial temperature were investigated by the study. About 97% of calcium hardness removal was achieved at a detention time of 12.5 minutes. It was concluded from the experiments performed that the optimum conditions for this system use a detention time of 12.5 minutes. This leads to an initial temperature of 70°C when using the heat exchanger. These conditions are valid for the range of Ca initial concentrations between 92 and 204 mg/L as CaCO₃. The residual concentrations under optimum conditions were 2.4, 2.5, 2.6, and 3 mg/L as CaCO₃ for initial concentrations of 92, 141, 172, and 204 mg/L as CaCO₃, respectively. The developed system proved to be practical in the continuous flow mode that simulates the actual operations in water treatment plants. It was concluded that MW energy could be one of the most effective methods for large scale removal of hardness from water.