Method and device for asymmetric polarity inversion in electromembrane processes

A method for asymmetric inversion of polarity for mitigating fouling and scaling on surfaces of membranes and interrupting a concentration polarization in electromembrane processes during both a cleaning operation and a normal operation, comprising:

• providing an electromembrane cell that comprises a pair of electrodes suitable for inversion of the polarity, one electrode acts as an anode and the other as a cathode, and a set of membranes;
• providing a bipolar switch that comprises at least four solid-state switches with an H-bridge configuration for adjusting an intensity of pulses applied in the electromembrane cell, wherein under normal operating conditions some solid-state switches are closed, and other solid-state switches are open for giving direction to a current;
• providing a device that varies a frequency of application of reverse polarity and pulse width, according to system requirements when the electromembrane process is running;
• providing two power sources different from each other for adjustment of the intensity of the pulses to deliver energy to the electromembrane cell, wherein one of the sources promotes the electromembrane process under normal conditions and the other source promotes the application of reverse polarity pulses in the electromembrane cell;
• passing a direct current through the bipolar switch in different directions, toward the electrodes, in which redox reactions take place;
• generating an electrochemical potential in the electrodes in order to induce the movement of ions toward different compartments of the cell;
• providing a microcontroller or a pulse generator for instructing the bipolar switch to change polarity;
• continuously measuring a voltage drop and/or electrical resistance in the electromembrane cell;
• defining a threshold value for the voltage drop and/or for the electrical resistance of the electromembrane cell;
• cleaning the membranes once said threshold value has been reached by application of inverse polarity asymmetric pulses with variable frequency and short pulse widths with values in between 10−5 and 100 seconds or by application of pause pulses;
• wherein the inverse polarity asymmetric pulses are applied with increasing frequency until reaching a threshold frequency value, the normal operation is halted and a high-frequency pulsing is applied of 101 to 107 Hz for 10−1 to 104 seconds for thoroughly cleaning the membranes;
• wherein the threshold frequency value is based on a work cycle of the process reaching 80.0 to 99.9%, which indicates need for thorough cleaning of the membranes with cleaning in place (CIP) procedures, wherein a work cycle of 80.0% means that 20.0% of the time is in a reversed polarity condition;
• and
• wherein the electromembrane process is continuous.