Abstract: In the ion exchange process, degradation of exchange resin capacity and loss of exchange performance due to various causes will cause abnormal operation of the switching system or decrease in the effluent water quality. At this time, the resin must be replaced or regenerated. Factors that cause degradation performance of exchange resin has a few main types as follows, according to different factors to take the appropriate method to process to help it restore exchange activity.

I. Deterioration of the resin

The deterioration of the resin mainly due to partly irreversible inactivation or permanently inactivation of the exchange resin caused by the factors of cracked resin, irreversible expansion of the oxidation or losses of active groups of ion exchange resin during the use of the resin. For the resin inactivation caused by deterioration, it is generally restore normal operation of the system only through the replacement of the resin. Because improper use or operation control will accelerate deterioration of the resin.

II. The pollution of the resin

The pollution of the resin generally known as poisoning of the resin, which divided into following three conditions:

1. The inorganics contamination is mainly due to the salt such as CuFeMnCaMgAl hydrolyse into hydroxyl floc in an alkaline environment and produce silica content if it has high silica in water. Such substances will block and affect the pore of the resin. When heavy metal ions exist, it will oxidize the resin, so as to change the structure of the resin and affect exchange capacity of the resin.

2. Organic pollution of the resin generally target on anion exchange resin. Organics in water is mainly humic acid and rich vitamin acid;

III. The pollution of microorganisms When the resin is stored or does not regenerated, resin adsorb algae and microorganisms in the water. Such microorganisms multiplied rapidly with absorption of nutrients of resin nitrates and amines. Microorganisms not only pollute the water but also damage the resin structure, which made the resin lower or loss of its exchange capacity. Therefore, in order to reduce pollution and poisoning of the resin, a pretreatment should be carried out before exchanging the raw water.