Warewasher and method for operating a warewasher

A warewasher having at least one treatment system comprising a jet system with at least one jet for spraying treatment liquid onto items to be cleaned within at least one treatment zone, a fresh water system and a control device, wherein the fresh water system has at least one water feed, at least one fresh water inlet for the introduction of fresh water into the at least one treatment system of the at least one treatment zone as well as a controllable capacitive deionization unit having at least one cell and connected on an input side to the at least one water feed and connected on an output side to a permeate outlet and a retentate outlet, wherein the permeate outlet feeds the at least one fresh water inlet and wherein the retentate outlet does not feed the fresh water inlet, wherein the at least one cell of the capacitive deionization unit is designed to be operated in any one of a plurality of operating modes including a deionization mode, in which a positive voltage is applied to a positive electrode of the at least one cell and a negative voltage is applied to a negative electrode of the at least one cell, and at least one further operating mode, wherein the control device is designed to change between operating modes of the at least one cell of the capacitive deionization unit in accordance with at least one operating parameter of the warewasher,

• wherein the at least one further operating mode of the at least one cell of the capacitive deionization unit is a regeneration mode, in which a negative voltage is applied to the positive electrode of the at least one cell and a positive voltage is applied to the negative electrode of the at least one cell, or a flush mode, in which no voltage is applied to the positive electrode or the negative electrode and water flows through the at least one cell to the retentate outlet and not to the permeate outlet,
• wherein the at least one operating parameter is an ion concentration of liquid in the at least one treatment zone, and wherein the ion concentration is detected by a concentration sensor of the warewash machine and the detected ion concentration is fed to the control device,
• wherein a washing program of the warewasher sets limit values for ion concentration of liquid in the at least one treatment zone, and
• wherein the control device is designed to select the deionization mode of the at least one cell of the capacitive deionization unit in response to the control device determining that the detected ion concentration of liquid in the at least one treatment zone exceeds an upper non-zero threshold limit value, and
• wherein the control device is designed to select the regeneration mode or the flush mode of the at least one cell of the capacitive deionization unit in response to the control device determining that the detected ion concentration of liquid in the at least one treatment zone falls below a lower non-zero threshold limit value.