disclosed is a novel proton - exchange membrane based solid polymer electrolyte electrochemical oxygen control system that can deplete and control the oxygen from a closed container to levels sufficient for both disinfestation and preservation . with the use of this electrochemical process , many insects that infest raw agricultural products and other produce can be exterminated , without detriment to the quality of the produce and without deposition of harmful residue , by reducing the ambient oxygen to a controlled low level for several days . the electrochemical process features the use of a bipolar stack comprised of a selected number of pem cells connected electrically in series and separated by an electrically conductive bipolar plate . each cell contains a membrane and electrode assembly , consisting of an anode structure and cathode structure in intimate contact with a pem . when dc power is applied to the cell stack , electrons are supplied to the cathode , supporting reduction of oxygen at the cathode with the formation of water , and electrons removed from the anode , supporting oxygen evolution by the decomposition of water at the anode . the anode and cathode compartments are separated by the solid ionomer pem , which transports protons generated at the anode through the pem to the cathode to complete the electrical circuit internally . oxygen is depleted by recirculating the gas in the dosed container over the cathode , and expelling the oxygen evolved at the anode by separating the oxygen from the recirculating anode water stream and venting it to the outside of the closed container . nitrogen or other inert gas is added as makeup gas to avoid creating a negative pressure in the container . a unique feature of this process is that at a low oxygen concentration , the cell and stack cathode current becomes rate - limited in direct proportion to the oxygen level in the recirculating gas and can therefore be used as a measure of the container oxygen level . in the sensing / control scheme developed as part of this invention , the current is periodically allowed to rise to the diffusion limit in a “ measure mode ” and then reset according to the desired oxygen level , determined from a slope - intercept “ measure mode ” calibration curve , for a longer “ control mode ” period .