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Water Softener Resin Regeneration

The fundamental reason behind the term ‘resin regeneration’ is to be able to replenish spent resin back to is proper ionic form ready to be able to be put back to service. This article hopes to provide the user with knowledge about the basics of resin regeneration with regard to water softeners.

Water Softeners

Typically the ending of a softener service cycle is concluded either through a timed program operation, overall gallon throughput, or even through an excessive reading of hardness within the softener effluent. Following either one of these 2 a regeneration sequence is then carried out.

The Backwash Cycle

The backwash routine increases the resin bed out of it’s resolved and packed status, and also washes the resin through flushing away any kind of suspended solids which might have already been filtered in the course of the service run. Resin particles will work as efficient filtration media due to the fact they possess ionic charges, that can coagulate fine contaminants. In the course of the backwash, all of the resin beads rub against each other, it is this scrubbing up action helps to clear built up dirt and / or iron coming from the surface of the beads. The backwash flow furthermore gets rid of any kind of damaged resin particles and also resin fines. as well as this the backwash routine classifies the bed with the more substantial resin beads on the bottom level along with the finer resins on the top. This specific process delivers the most effective conditions to allow for an excellent uniform circulation of brine, rinse and service.

It is advisable to increase the water softener resin bed by around 50% and also to get the period of the backwash cycle prolonged enough in order to efficiently eliminate all of the resin fines as well as various other suspended solids. In ambient temperatures (about 60°F), making use of normal softening cation resin along with a flow rate of 6 gpm per square foot of surface area for a timeframe of ten to fifteen minutes will be enough. It will be extremely beneficial to seek advice from manufacturers’ document with regard to the specific resin currently being regenerated for you to discover the appropriate backwash flow rate. The backwash flow rate will be established on temperatures; less hot water swells the bed much more than hotter water.

Brine Intro

Sodium chloride is employed as the regenerant compound for transforming depleted softener resin back again to a sodium form. The resin exchanges the accumulated hardness upon the bead with the sodium ion existing within the sodium chloride. It is placed to the bed at a content level of 8-12% commonly, 10% is the optimum. A contact period of thirty minutes is suitable. The overall contact time is determined via the period the brine is released to the bed until such time as it is displaced from the bed in the course of a slow rinse. Salt dose range is 6 to 15 lb for every cubic ft.

The Slow Rinse

The slow rinse takes away from the bed the quantities of brine regenerant which still remains within the vessel
. It is the most uncontaminated brine that the resin is going to come in to contact with, therefore it is essential to not flush it out too rapidly. Throughout the slow rinse routine, the valve out of the concentrated brine is closed, and just the dilution water will be released to the bed at the dilution water flow rate. It will help when the dilution water as well as the slower rinse water are taken from a softened water source.

The Fast Rinse

The last action is to perform a fast rinse, This is performed at the service flow rate. This fast rinse phase gets rid of any kind of left over brine coming from the resin beads and assists in flushing away any kind of brine which might still be found within the dead regions within the tank. The minimum amount advised for flow rate is 1 to 1.5 gpm per cubic foot.

Twin Bed Deionisers

The regeneration associated with cation as well as anion exchange resin employed within deionisers is a far more complex procedure when compared with straight forward softening. The procedure consists of the implementation of strong acid and also caustic. It is crucial to comply with the correct safety factors with regard to dealing with these types of chemicals and the resulting waste materials.

A strong acid cation unit exchanges calcium, magnesium and sodium, etc., with its active ions, hydrogen. The strong base anion unit within a twin bed deioniser exchanges sulfate, chloride, alkalinity and silica ions with hydroxide. This process gradually decreases the concentration of obtainable active ions. The resin is regarded as depleted as soon as the active ion concentration gets to a low level.


During the service cycle, the resin bed accumulates suspended impurities coming from water. Many of the media particles/beads may split up in to fines, and the bed will become to some degree compacted. Adding water at determined flow rates in the reverse direction to the service flow elevates the bed, which in turn loosens up and increases into the free board. This allows the suspended particles and also media fines away and out of the unit. At the very same moment, the bed will lose its compaction, decreasing the possibility of channeling, that may result in water or regenerant chemical substances to avoid some of the efficient media bed. Compaction as well as fines additionally generate extreme pressure drop.

Water of the exact same quality as the influent is brought in from the bottom part of the vessel, gathered at the top and led to drain. Correct backwash rate is very important considering that rates greater than recommended may well result in media loss, and also reduced rates might not be adequate to finish the backwash correctly. Any kind of sudden shock within the backwash cycle must be avoided, because this also might bring about media loss.

Seek advice from your resin spec sheets with regard to the correct backwash flow rate for the reason that cation and anion resin densities tend to be very different. Typically, cation backwash flow rates will be in the range of 6 gpm per square foot of surface area, and the anion backwash flow rate is usually half of that.

Regenerant Introduction

Regenerant’s of appropriate concentration are introduced straight into the tanks to reactivate the resin. The potency of dilute regenerant as well as it’s flow rate are of extreme significance. Any kind of transformation within these values in comparison to the ones specifically recommended might result in resin fouling, capacity reduction as well as quality deterioration. In certain cases, the regenerant has to be warmed up to a specific temperature in order to complete a correct elution..

If dilute sulfuric acid is made use of, the percent concentration is generally employed in a step by step fashion; for example, the very first half of the dosage is employed at 2% and the second half at 4%. The precise concentration of sulfuric applied is determined through the quantity of calcium that is actually present within the water currently being addressed throughout the service cycle. Since the resin is eliminating and concentrating calcium ions, the possibilities for the precipitation of calcium sulfate is present when the sulfuric acid is introduced.

The contact time for the acid regenerant introduction ought to be close to thirty minutes, and the flow rate will need to be roughly .5 to 1 gpm per cubic foot. (Whenever making use of sulfuric acid, it is sensible to design around the high end of the suggested regenerant flow rate.)

Displacement – Slow Rinse

The procedure of displacement of regenerant’s and the eluted ions from the resin is commenced at a gradual pace, usually at a similar flow rate as the dilute regenerant has been placed.

Fast Rinse

Following the slow rinse, resin is rinsed more, but this time at a greater flow rate. Rinsing gets rid of the excess regenerant coming from the resin. At the same time,the eluted ions will be displaced from resin bed, thus, bringing the resin back to an active useable condition.