Regenerable biocide delivery unit

An apparatus for continuous treatment of water to impart a predetermined residual of I.sub.2 therein comprising

• a bed of anion exchange resin iodinated to a selected iodine content and having an inlet and an outlet,
• a first conduit connected to the inlet of said anion exchange resin bed and connected to a source of water requiring treatment,
• a second conduit connected to said anion exchange resin bed outlet and comprising means for discharging treated water therefrom,
• a bed of iodine crystals having an inlet and an outlet,
• a third conduit connecting said iodine bed outlet to said first conduit,
• a fourth conduit connected to said iodine bed inlet and connected to said source of water, and
• valve means connected to said first conduit and said fourth conduit and to said source of water for directing flow of water to said second conduit selectively through said bed of iodine crystals and then through said resin bed via said fourth conduit or through only said resin bed via said first conduit.

A method of treating water to produce a predetermined I.sub.2 residual therein comprising

• providing a bed of anion exchange resin iodinated to a selected iodine content,
• flowing water requiring purification through said iodinated anion exchange resin to remove iodine from said resin and produce said predetermined I.sub.2 residual therein,
• continuing flowing said water through said bed of anion exchange resin until the effluent iodine content is reduced to a selected lower level,
• preparing in-situ an aqueous solution of I.sub.2, passing said solution through said bed in-situ to re-iodinate said resin to said selected iodine content, and
• flowing further amounts of water requiring purification through said iodinated anion exchange resin to remove iodine from said resin and produce said predetermined I.sub.2 residual therein.