A suppressor device for an ion chromatograph is provided between a separation column and a detector of an ion chromatograph. An electrodialysis suppressor includes a first flow path to which an eluent flowing from the separation column is supplied, a second flow path to which a regeneration liquid is supplied, an ion exchange membrane provided between the first flow path and the second flow path and an electrode to which a voltage is applied. A power supply circuit that applies a voltage to the electrode is turned off in a case in which an eluent is not supplied to the first flow path of the electrodialysis suppressor.

A suppressor device for an ion chromatograph is provided between a separation column and a detector of an ion chromatograph. An electrodialysis suppressor includes a first flow path to which an eluent flowing from the separation column is supplied, a second flow path to which a regeneration liquid is supplied, an ion exchange membrane provided between the first flow path and the second flow path and an electrode to which a voltage is applied. A power supply circuit that applies a voltage to the electrode is turned off in a case in which an eluent is not supplied to the first flow path of the electrodialysis suppressor.

Electrodeionization and electrodialysis systems which eliminate or substantially prevent the feed water from entering the concentrating compartments, for improving the recovery of product water as well as improving the current efficiency. Electro-osmotically generated flows of water entering from the diluting compartments of the stack constitutes the majority of concentrate feed, leading to the production of high purity, desalinated waters in the diluting compartments and highly concentrate solutions in the concentrate compartments.

Electrodeionization and electrodialysis systems which eliminate or substantially prevent the feed water from entering the concentrating compartments, for improving the recovery of product water as well as improving the current efficiency. Electro-osmotically generated flows of water entering from the diluting compartments of the stack constitutes the majority of concentrate feed, leading to the production of high purity, desalinated waters in the diluting compartments and highly concentrate solutions in the concentrate compartments.

The present disclosure is directed to ion-exchange systems and devices that can monitor key parameters related to the performance of the ion-exchange device. Specifically, the ion-exchange systems and devices disclosed herein can provide real time voltage drop across groups of membrane pairs using diagnostic spacer borders between the pairs. In addition, the ion-exchange systems and devices disclosed herein can monitor the compression force applied by the compression plates holding the ion-exchange systems and devices together.

An ocean alkalinity enhancement (OAE) system that reduces atmospheric CO.sub.2 and mitigates ocean acidification by electrochemically processing feedstock solution (e.g., seawater or brine) to generate an alkalinity product that is then supplied to the ocean. The OAE system includes a base-generating device and a control circuit disposed within a modular system housing deployed near a salt feedstock. The base-generating device (e.g., a bipolar electrodialysis (BPED) system) generates a base substance that is then used to generate the ocean alkalinity product. The control circuit controls the base-generating device such that the alkalinity product is supplied to the ocean only when (1) sufficient low/zero-carbon electricity is available, (2) it is safe to operate the base-generating device, and (3) supplying the alkalinity product will not endanger sea life. Modified BPED systems include features that facilitate autonomous system operations including enhanced maintenance cycle operations and a reduced reliance on external fresh water sources.

A resin-wafer electrodeionization (RW-EDI) apparatus for purifying water for coffee brewing comprises a cathode; an anode; and multiple porous solid resin wafer exchange units arranged in a stack between the cathode and the anode, and an air distributor adapted and arranged to aerate the water to be purified. Each unit comprises a monovalent cation exchange membrane (CEM), an anion exchange membrane (AEM), and an ion exchange resin wafer between the CEM and the AEM, which is in contact with, and in fluid flow connection with the CEM and AEM. Each resin wafer comprises a cation exchange resin and an anion exchange resin. The units are oriented with the CEM facing the cathode and the AEM facing the anode, with space between the units defining ion concentrate chambers. Bipolar ion exchange membranes separate the anode and cathode from their nearest resin wafer exchange units.

An electrodialysis apparatus comprises a first reservoir wherein salt dissolved in solvent is reduced below a threshold concentration and a second reservoir wherein the salt concentration increases. A first electrode contacts a first solution of a first redox-active electrolyte material, and a second electrode contacts a second solution of a second redox-active electrolyte material. A first type of membrane is disposed between the first and second reservoirs and a second type of membrane is disposed between the first electrode and the first reservoir and between the second electrode and the second reservoir. A color measuring device is coupled to at least one of the solutions, and a control system is configured to modify the value of a property of at least one of the first and second solutions in response to detecting a color value of one of the solutions exceeding a threshold color value.

An electrodialysis apparatus comprises a first reservoir wherein salt dissolved in solvent is reduced below a threshold concentration and a second reservoir wherein the salt concentration increases. A first electrode contacts a first solution of a first redox-active electrolyte material, and a second electrode contacts a second solution of a second redox-active electrolyte material. A first type of membrane is disposed between the first and second reservoirs and a second type of membrane is disposed between the first electrode and the first reservoir and between the second electrode and the second reservoir. A color measuring device is coupled to at least one of the solutions, and a control system is configured to modify the value of a property of at least one of the first and second solutions in response to detecting a color value of one of the solutions exceeding a threshold color value.

A control system includes one or more levels of control of power and energy. At one level, a first controller optimally divides power between two or more processes, to maximize instantaneous production, for a given amount of currently available power. In the case of EDR desalination, electric power is optimally divided between ion exchange membranes and pumps to maximize instantaneous production of desalinated water for a given amount of available electric power. Optionally, at another level, a second controller divides time-varying power between the processes fed by the first level controller and an energy storage unit, based on a prediction of future power availability and a function. In the EDR case, power generated by a photovoltaic array is divided between the EDR desalination process and a battery, based on a prediction of future PV power availability and a function, to ensure reliable water production in the future.