Water treatment process eliminating carbon dioxide for industries demanding high purity

摘要

A water treatment process which reduces the carbon dioxide concentration, passing pre-treated water leaving the first reverse osmosis unit through a bed of charged weakly-cationic exchange resin, before entering the second, is new. To reduce carbon dioxide concentration, pre-treated water leaving the first reverse osmosis unit (1) is passed through a bed (14) of charged weakly-cationic exchange resin, before entering the second (9). An Independent claim is included for the corresponding water treatment plant. Preferred features: The resin is charged with alkali metal-, especially sodium ions ions or ammonium ions. In addition, flow into the second reverse osmosis unit (9) is joined by water leaving the concentrate outlet (13) of the second unit, which has first been passed through a second bed of weakly cationic exchange resin (15). Beds are interchanged at intervals. Bed percolate may be added to concentrate from the second unit, and supplied to join feed water to the first unit. To compensate cation loss, lye is dosed to concentrate from the second unit, before entry into the bed. The second reverse osmosis unit has a positively-charged semipermeable membrane. Permeate leaving the second unit is treated in a further resin bed with weakly acidic resin. Pure water is recovered as percolate from the bed. Permeate leaving the second reverse osmosis unit passes to a third reverse osmosis unit (16), for which connections are detailed. The second membrane may be negatively charged.