Electrodeionization system

An improved electrodeionization system for removing ions from liquids passed therethrough, comprising:

• a flow-through electrodeionization module having a liquid inlet and a liquid outlet;
• a power supply electrically connected to said electrodeionization module electrodes so as to establish a voltage gradient thereacross;
• a resistivity monitor for monitoring the resistivity of the liquid output flow from said electrodeionization module;
• means for establishing a target resistivity range for said liquid output flow;
• and
• a proportional band control means, responsive to said resistivity monitor and said target resistivity range, for proportionally controlling the amount of time that said power supply is turned on such that said power supply is continuously on when said resistivity is below said range, is continuously off when said resistivity is above said range, and is intermittently on when said resistivity is within said range.

An improved electrodeionization system for removing ions from liquids passed therethrough, comprising:

• a flow-through electrodeionization module;
• a power supply electrically connected to said electrodeionization module electrodes so as to establish a voltage gradient thereacross;
• a resistivity monitor for monitoring the value of a property of the liquid output flow from said electrodeionization module;
• and a
• a control circuit responsive to said resistivity monitor, said control circuit controlling the amount of time that said power supply is turned on and for controlling the amount of time said power supply is turned off.