CQ-N250 Nitrate anion resin media

CQ-N250 is a macroporous strong base anion resin which is specially designed for the removal of nitrates from water for potable processes. The macroporous matrix and special ion exchange group functionality imparts ideal nitrate selectivity to CQ-N250 making this resin particularly suitable for nitrate removal even when moderate to high concentrations of sulphate are present. Hence this resin gives superior performance in nitrate removal applications when compared with standard exchange resins. A requirement of the nitrate removal process is to produce potable water meeting the quality standard defined by the European Economic Community in the Directive No. 80/778 of July 1980. This directive limits the nitrates to a maximum admissable concentration (M.A.C.) of 50 mg NO3/l. The U.S.A. drinking water regulations limit nitrates to 45 mg NO3/l.

OPERATING PERFORMANCE

The high selectivity of CQ-N250 for nitrate over sulphate ensures that any necessary reduction in nitrate levels can be achieved even in the presence of high influent sulphate concentration. Hence it so offers the advantage over standard strong base resins that its exchange capacity for nitrates is less affected by a high influent concentration of sulphate. For this reason, although CQ-N250 has a lower total exchange capacity than standard strong base anion resin, its use can produce advantageously higher throughputs for the following reasons.

Both standard gel type or macroporous strong base resins are quite capable of effective nitrate removal where sulphate to total anion ratios are low. However, on account of the high selectivity for sulphate in dilute solutions which follows the order,

HCO3- < Cl- < NO3- < SO4=

selective displacement of nitrate by sulphate results in the effective nitrate removal capacity being reduced by sulphate loading. Apart from the obvious disadvantage of the reduction of treated water obtained on cycling, the exchange of both nitrate and sulphate by chloride will result in a less palatable and sometimes less acceptable water than the influent supply, in that the treated water may be more corrosive and the limits for chloride concentration may be exceeded.