A bipolar membrane BP characterized in that particles 5 of a basic metal chloride are distributed in the interface between a cation-exchange membrane 1 and an anion-exchange membrane 3.

A continuous resin regeneration system includes a process by which resin in need of being recharged is continuously recharged and cleaned with a plurality of two-set filtration columns so that resin regeneration and the flow of influent is continuous and interrupted. Downstream filtration columns also undergo this cycling but at slower and related rates as the first column with the dirtiest water will naturally degrade resin faster than the downstream columns. Contaminated influent is cleaned by the continuously recharged resin in multiple column sets. The degree of cleaning of earlier filtration columns affects the resin flow rate of later filtration columns.

A continuous resin regeneration system includes a process by which resin in need of being recharged is continuously recharged and cleaned with a plurality of two-set filtration columns so that resin regeneration and the flow of influent is continuous and interrupted. Downstream filtration columns also undergo this cycling but at slower and related rates as the first column with the dirtiest water will naturally degrade resin faster than the downstream columns. Contaminated influent is cleaned by the continuously recharged resin in multiple column sets. The degree of cleaning of earlier filtration columns affects the resin flow rate of later filtration columns.

Water softening device includes water softening tank and neutralizing tank. Water softening tank softens raw water containing a hardness component by weakly acidic cation exchange resin. Water softening tank includes first water softening tank and second water softening tank. Neutralizing tank neutralizes the pH of softened water that has passed through water softening tank by weakly basic anion exchange resin. Neutralizing tank includes first neutralizing tank and second neutralizing tank. Water softening device is configured to cause raw water containing a hardness component to flow through first water softening tank, first neutralizing tank, second water softening tank, and second neutralizing tank in this order.

Water softening device includes water softening tank and neutralizing tank. Water softening tank softens raw water containing a hardness component by weakly acidic cation exchange resin. Water softening tank includes first water softening tank and second water softening tank. Neutralizing tank neutralizes the pH of softened water that has passed through water softening tank by weakly basic anion exchange resin. Neutralizing tank includes first neutralizing tank and second neutralizing tank. Water softening device is configured to cause raw water containing a hardness component to flow through first water softening tank, first neutralizing tank, second water softening tank, and second neutralizing tank in this order.

The present invention relates to aluminium-doped chelate resins containing iminoacetic acid groups, to a production process for aluminium-doped chelate resins containing iminoacetic acid groups, and to a device comprising at least one layer of at least one aluminium-doped chelate resin containing iminoacetic acid groups, and to the uses of this device and of the chelate resins for removal of fluoride from water.

The present invention relates to aluminium-doped chelate resins containing iminoacetic acid groups, to a production process for aluminium-doped chelate resins containing iminoacetic acid groups, and to a device comprising at least one layer of at least one aluminium-doped chelate resin containing iminoacetic acid groups, and to the uses of this device and of the chelate resins for removal of fluoride from water.

A method of producing treated ion exchange resin material includes exposing an enclosed vessel containing ion exchange resin and a pre-treatment solution to high energy radiation. The treated ion exchange resin material has reduced organic impurities or total organic carbon (TOC).

A method of producing treated ion exchange resin material includes exposing an enclosed vessel containing ion exchange resin and a pre-treatment solution to high energy radiation. The treated ion exchange resin material has reduced organic impurities or total organic carbon (TOC).

There is provided a method for obtaining a purified aqueous solution of silicic acid containing less metal impurities such as Cu and Ni using water glass as a raw material with less number of purification steps than that in conventional methods without using any unnecessary additives. The method for producing a purified aqueous solution of silicic acid, the method comprising the steps of: (a) passing an aqueous solution of alkaline silicate having a silica concentration of 0.5% by mass or more and 10% by mass or less through a column filled with a polyamine-, iminodiacetic acid-, or aminophosphoric acid-type chelating resin, and (b) passing the aqueous solution passed in the step (a) through a column filled with a hydrogen-type cation exchange resin.