Abstract: An apparatus for delivering dissolved chlorine dioxide into a water system comprises sources for acid, a chlorite, and a chlorine donor solutions and metering pumps. The solutions are mixed whereby chlorine dioxide is generated, which is then fed into a water system.

Abstract: A solution for genenting chlorine dioxide is disclosed. Th solution comprises a chlorlte, a chlorite donor, an alkali and water. The chlorine dioxide is released by adding an acid to the solution. Also disclosed are methods for preparing and using the solution.

Abstract: A method comprises feeding a chlorite, a chlorine donor, and an acid into a water line connected to a water system through which water is flowing, or a mixing chamber connected to a water system, wherein the chlorite and chlorine donor being present in a molar ratio from 1.0:0.1 to 1.0:15.0 chlorite to chlorine donor; whereby chlorine dioxide is generated substantially instantaneously in solution and substantially no undissolved chlorine dioxide gas is evolved; and feeding the solution comprising chlorine dioxide into the water system. The solution comprising chlorine dioxide in the mixing chamber can have a chlorine dioxide concentration from 20,000 to 50,000 ppm.

Abstract: A solution for generating chlorine dioxide comprises a chlorite, a chlorine donor, an alkali, and water. Substantially all of the chlorite is converted to chlorine dioxide upon acidification of the solution. Methods for preparing and using the solution are based on such solution.