Organic removal

Organic removal
Dealkalisation is not the only ion-exchange process that is currently finding a place within the soft drinks industry.

The coagulation process not only reduced the alkalinity content of the water but also removed the organic matter as part of the flocculation reactions.

The dealkalisation process, however, is specific to the removal of alkalinity from water and all other constituents in the feed water will remain unaffected.

Organic matter in the raw water may cause taste and odor problems in the carbonated product, particularly after sterilization using chlorine.

In some areas the naturally occurring organic matter reaches levels where it is likely to give color to the water, which will necessitate its removal to meet the required specifications.

Other waters may also contain significant concentrations of organic matter (colorless to the naked eye) which will depend upon the nature and type of the organic molecule as well as the concentration.

In these circumstances organic removal must be considered a necessity.

Removal of organic matter by ion exchange was developed in the 1960s as a method of protecting anion exchange resins in a demineralization plant in order to maintain the quality of treated water produced.

The process uses an organic scavenger resin operating in the chlorine form. Natural organic matters are complex organic molecules that contain carboxylic acid active groups, meaning that they will act as weak anions, and will be held on the organic scavenger.

The organic scavenger is a highly porous resin that will allow the organic molecules easy passage in and out of the structure.

Ion exchange resins with a macroporous or macroreticular structure are particularly suited to this application and offer physical strength coupled with capacity and reversibility of organics during regeneration.

As ion-exchange treatment will only remove about 70% of the organic matter of the residual organic concentration after scavenger treatment is high enough to cause problems with the final product.

As a general rule waters having an organic content above 1ppm as measured by the 4 hours at 27 degree C permanganate test will require treatment while those waters that have a concentration at 1 ppm or below will not normally require special treatment.

Regeneration will use 10% sodium chloride prepared from concentration brine, though under certain conditions regeneration will be made with a mixture of 10% sodium chloride hydroxide and 2% sodium hydroxide, which will give the scavenger an operating capacity.

The regenerant will displace almost all of the organic matter absorbed in the previous operating cycle but some residue will remain in the resin and will require other regeneration techniques such as hot soaking or alkaline brine regeneration to assist in its removal.

Under certain condition the residue will not ne removed by any means and this residue will be classed as irreversible fouling of the resin.

The irreversible fouling of the resin will progressively increase and there will come a tome when the fouling threshold will reach such a level indicating that the economic life of the resin has been reach, which will mean that the resin must be changes.

Alkaline brine regeneration tends to remove more of the absorbed organic matter from the resin and therefore the build up of irreversible fouling will be slower.
Organic removal