A Combined Heat- and Power-Driven Membrane Capacitive Deionization System

Here, we experimentally investigate an alternative membrane capacitive deionization (MCDI) system cycle, which aims to reduce the required electrical energy demand for water treatment. The proposed heat and power combined MCDI system utilizes waste heat to control the electrostatic potential of the charged electrodes during the charging (desalination) and discharging (energy recovery) processes. The experimental findings suggest that with an increase in the temperature of the brine from 20 to 50 °C, the electrical energy consumed can be reduced by nearly 10%. We also show that the dependence of electrostatic potential on concentration may limit energy recovery performance (power), when moving toward higher water recoveries. Alternative desalination cycles can be further explored through evaluating non-isothermal and non-adiabatic system operation.