Water Softener Regeneration

Regular water softener regeneration is an essential process required to maintain the effectiveness of ion-exchange resins used to soften hard waters. In this guide the pre-treatment specialists at Water Treatment Services examine the need for softeners in commercial, industrial and process applications. The guide looks at how the ion-exchange process works, and the stages required to complete a full regeneration of the resin media. It reviews the benefits of base-exchange softening and concludes with a brief review of equipment selection and pre-installation issues.

How do water softeners work?

Hard water when used in industrial and commercial applications can create a range of problems, some of which can be significant. The most common effect is usually the build-up of limescale on equipment surfaces including boilers and steam generators, cooling towers, industrial washing machines, pipes and other water system components. Limescale or simply scale is caused when there are excess calcium and magnesium salts dissolved in the water which precipitate out and adhere to equipment surfaces.

Limescale can seriously damage equipment such as heat exchangers, in the same way as it builds up on the heating element of your kettle at home. Hard water also stops soap lathering up as much, so has an impact on the efficiency of many cleaning processes. For all of these reasons, it is normal practice to take steps to soften water before it’s used, especially in hard water areas.

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Base-exchange or sodium-cycle softening

Base-exchange or sodium-cycle water softening is one of the most commonly used ways of softening hard water in industrial and commercial applications. The process involves the use of a chemical medium or ion-exchange resin which helps to remove the harmful “hard” magnesium and calcium ions from the water, replacing them with other, less damaging sodium ions. This process is referred to as ion-exchange.

Over time however, the softener medium becomes saturated with the ions it has taken out of the water. Once this happens the resin needs to be regenerated to allow it to continue working properly. Water softener regeneration involves recharging or regenerating the resin beads using a heavily concentrated solution of sodium chloride (brine) which is used to reverse the effects of the ion exchange process.

The regeneration of base-exchange or sodium-cycle softener resins typically takes up to 3 hours to complete and involves four main steps in the softener regeneration process:

Backwash
Backwash reverses the flow of water through the softener resin to dislodge any solids or fines which have accumulated on top of the resin. It also helps to reverse any compaction of the beads that may have occurred during the service cycle. If the backwash is effective, it only takes around 10 minutes to expand the resin bed by 50%. When the water starts to run clear, the backwash cycle is finished.
Brine draw
After the backwash stage is finished, an 8% to 12% brine solution (sodium chloride) is pumped onto the resin bed and left for around 20 minutes. The large number of sodium ions contained in the brine solution works to remove the hardness from the resin beads, and replaces it with sodium ions. The effectiveness of a brine draw is typically dependent on a number of factors including the volume and hardness of the water processed by the softener, the levels of sodium depletion that have occurred, and the size of the resin bed itself.
Slow rinse
After the brine draw stage has been successfully completed, rinse the resin bed thoroughly with clean, fresh water at the same rate. A slow rinse will help to wash any excess brine out of the resin bed and will complete the ion exchange process.
Fast rinse
The fast rinse is the final step in the water softener regeneration process, and increases the speed of the fresh water rinse to around 10 litres per minute. This process can typically take anything between 20 and 50 minutes. This fast rinse stage helps to flush any hardness and excess brine solution out of the resin bed particularly where reduced water flow occurs.

The benefits of base exchange softening

Preventing the build-up of scale in steam boilers, cooling towers and commercial washing machines is an essential pre-treatment process used in hard water areas to ensure heat transfer efficiencies are maintained, and equipment continues to perform as it should.

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Base-exchange or sodium cycle water softeners provide an excellent solution to limescale problems offering a number of benefits. They are very efficient at reducing levels of water hardness, they are easy to install, simple and reliable to operate, and cost effective in use.

Softener selection and pre-installation considerations

While sodium cycle softeners can be used to great effect there are a number of issues that need to be considered before they are installed, including:

Metal contamination
Contamination of the softener resin from metals such as iron, manganese and aluminium can cause increased fouling and lead to poor water quality issues. To control this, the resin should be regularly cleaned.
Chlorine
High levels of chlorine (above 0.5ppm) and other strong oxidising agents in the water can result in accelerated deterioration of the softener resin and should be controlled, usually using a carbon filter.
Turbidity
Where turbid water conditions exist the use of ion exchange resins should be avoided as accelerated fouling and poor water quality issues can result.
High silica/alkalinity
The use of base-exchange softeners may not be suitable under high silica or alkaline water conditions. Where such conditions exist alternatives methods of pre-treatment may need to be considered.

Commercial water softener equipment and service specialists

Water Treatment Services offer a range of high performance equipment and service solutions for the pre-treatment of industrial and process waters including the design, installation and maintenance of water softeners. Our experts can help you optimise costs and operational efficiencies, reduce downtime, achieve water and energy savings and increase plant reliability and safety.

With offices in London serving the South and South East England, Manchester (North West), Birmingham (Midlands), Bristol (South East England and Wales), Leeds (North and North East) and Glasgow (Scotland), supported by regional teams of specially trained technicians and engineers we can offer professional, cost effective softener design, installation and services solutions throughout the UK and Internationally.

Contact us today to learn how our expert water treatment service solutions, including water softener regeneration, can help you.