Ion exchange

Demineralisation (DM) & Mixed Bed PlantsWater stripped down to its purest.

A DM plant removes almost all dissolved minerals from water using ion exchange resins. A mixed bed polishes it further, for boilers, laboratories and processes that need very pure water.

Request a proposalHow it works
  1. 01Pre-filtration
  2. 02Cation exchange
  3. 03Degasser
  4. 04Anion exchange
  5. 05Mixed bed polish
  6. 06Regeneration

What it is

In plain words.

Water carries dissolved minerals as charged particles: cations such as calcium, magnesium and sodium, and anions such as chloride, sulphate and bicarbonate. A DM plant passes water through two resin beds. The first swaps every cation for hydrogen, the second swaps every anion for hydroxide, and the hydrogen and hydroxide combine to form water. What comes out is close to distilled quality.

A degasser between the beds strips out carbon dioxide, which lightens the load on the anion resin. A mixed bed unit, where both resins sit together, polishes the water further. Our DM units use single-valve operation with each step marked on the valve, are assembled and checked before dispatch, and are built rust-free. We design, supply, install, commission and maintain them.

How it works

Stage by stage.

  1. Pre-filtration

    Sand and carbon filters remove suspended solids and chlorine, which would foul or damage the resin.

  2. Cation exchange

    Resin in hydrogen form swaps calcium, magnesium and sodium for hydrogen ions.

  3. Degasser

    Air blown through the water strips out carbon dioxide formed in the cation stage.

  4. Anion exchange

    Resin in hydroxide form swaps chloride, sulphate and other anions for hydroxide ions.

  5. Mixed bed polish

    Cation and anion resins mixed in one vessel remove the last traces of dissolved salts.

  6. Regeneration

    Spent resins are recharged: cation with acid, anion with caustic soda, then rinsed for service.

Options

Built to suit the site.

  • Two-stage DM

    A cation bed followed by an anion bed. The standard choice for most boiler and process water.

  • DM with degasser

    Adds a degasser tower between beds to remove carbon dioxide and reduce caustic use.

  • Mixed bed polisher

    Cation and anion resins in one vessel, used after DM or RO when very pure water is needed.

  • Manual or automatic

    Manual single-valve units for smaller plants, or automatic regeneration under PLC control.

Where it's used

Industries and sites.

  • Boiler feed
  • Pharmaceuticals
  • Automobile & battery
  • Chemicals
  • Hospitals
  • Breweries
  • Fertilisers
  • Power plants

See how we work with each industry →

What we deliver

One team, from survey to service.

  • 01

    Design

    Survey, water or effluent analysis, process design and sizing for your site.

  • 02

    Build

    Supply, fabrication, civil and mechanical works, installation and commissioning.

  • 03

    Automate

    PLC, SCADA and remote monitoring, so the plant can be seen and controlled from anywhere.

  • 04

    Maintain

    Operation, preventive maintenance and AMC under Zeal-Care, with written reports.

Questions

Asked before every project.

What is the difference between a softener and a DM plant?

A softener only swaps hardness minerals for sodium, so dissolved salts stay in the water. A DM plant removes almost all dissolved salts, giving water close to distilled quality.

Should I use RO or DM?

RO suits higher-salt water and removes most dissolved solids without regeneration chemicals. DM gives higher purity. Many plants use RO first and a mixed bed after it for the final polish.

How often do the resins need regenerating?

That depends on the salt content of your feed water and how much you treat. We size the beds to give a practical run between regenerations and set this out in the design.

Water treatment

Often built together.

Tell us about your site.

Share your flow, location and timeline. An engineer will review your requirement and call you back within one working day.

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