ENV · Post-treatment
Ion exchange, mixed bed and electrodeionization
The polishing stage that decides whether your water is fit for a boiler, a reactor or a wafer. Resin-based demineralisation, and chemical-free EDI where regeneration chemicals are unwelcome.
The starting point
What problem does it solve?
- “Our boiler tubes are scaling again”
- “Handling acid and caustic for regeneration is a safety issue”
- “Our conductivity spec keeps failing at the point of use”
- “The regeneration waste has become a discharge problem”
- “We need ultrapure water and don't know where to start”
Your solution can be ion exchange, mixed bed or EDI.
Post-treatment produces high-quality water for specific needs. It is the least glamorous part of a treatment plant and the part that most often decides whether the process upstream of it runs reliably. Hardness, silica and dissolved ions scale boiler tubes, reduce heat transfer, corrode equipment and raise fuel consumption. In semiconductor and pharmaceutical production, the smallest ionic contamination becomes a defect or a failed validation.
Glorinda Resins, a subsidiary of Glorinda, specialises in resins and offers over 200 types for various industries including water and wastewater treatment. That range is what lets us select on the chemistry rather than on what happens to be in stock.
Why it pays
Benefits
Over 200 resin types
Cation, anion, mixed bed, chelating, adsorbent, chromatography, powder, peptide carrier, enzyme carrier and agarose media — with resin screening and process design support before you commit.
Read moreChemical-free EDI
Electrodeionization produces ultrapure water by removing dissolved ions, minerals and impurities in a continuous, chemical-free process. No acid, no caustic, no regeneration waste.
Continuous operation
EDI runs continuously rather than in regeneration cycles, which removes the standby capacity a mixed bed train needs and simplifies the control philosophy.
Lower operating cost, smaller footprint
EDI operating costs are lower than mixed bed, maintenance is minimal, and the compact design has a smaller footprint because there is no acid and alkali storage to accommodate.
Verified against mixed bed
We publish the honest comparison rather than the sales one — including the fact that EDI's initial investment is about 20% higher.
Backed by technical service
Experimental demonstrations, resin screening, process optimisation, troubleshooting, installation and commissioning, and technical training for system operation.
Process
How it works
Both routes remove ions. They differ in how they regenerate, what they cost and what they leave behind.
Ion exchange passes water through resin beads that swap unwanted ions for hydrogen and hydroxide. When the resin is exhausted it is regenerated with acid and alkali. A mixed bed combines cation and anion resin in a single vessel and produces the highest quality achievable by resin alone.
Electrodeionization combines ion exchange resin with ion-selective membranes and a DC field. Ions migrate out of the product stream continuously and the field regenerates the resin as it goes — so there is no chemical regeneration at all.
Process diagram
RO permeate → EDI or mixed bed → distribution loop
Reserved for a static diagram showing a demineralisation train: pre-treatment, RO, the EDI and mixed bed alternatives in parallel, storage and the distribution loop with polishing at the point of use.
Static process diagram — final artwork to be supplied.
Feed conditioning
EDI and mixed bed both want a low-conductivity, low-hardness, low-organic feed. That normally means reverse osmosis upstream, and it means the RO stage has to be designed with the polisher in mind rather than as a standalone.
Ion exchange and mixed bed
Glorinda Resin's ion-exchange and mixed bed systems are suitable for oil, gas and petrochemical processes; power plant processes; environmental processes, recycling and separation; and food processing and pharmaceutical industries. Regeneration uses acid and alkali, which has to be stored, handled and neutralised.
Electrodeionization
Produces ultrapure water by removing dissolved ions, minerals and impurities in a chemical-free, environmentally friendly, continuously operating process. EDI uses Glorinda Resins' advanced ion exchange materials and is well suited to plants where chemical handling is a safety, permit or logistics problem.
Selection
The comparison table below is the one we work from. EDI costs about 20% more to install and less to run; mixed bed costs less to install and about 12.5% more to operate, and generates hazardous waste liquids during acid-base regeneration. Space, maintenance capability and the site's attitude to bulk chemicals usually settle it.
| Category | EDI (electrodeionization) | Mixed bed |
|---|---|---|
| Regeneration | No regeneration required | Requires frequent regeneration with acids and alkalis |
| Environmental impact | Environmentally friendly | Generates hazardous waste liquids during acid-base regeneration |
| Initial investment | About 20% higher than mixed bed systems | Lower initial investment |
| Operating costs | Lower than mixed bed | 12.5% higher than EDI |
| Maintenance | Minimal maintenance | Complex maintenance |
| Space requirements | Compact design with a smaller footprint | Requires larger space due to additional facilities for acid/alkali storage |
Source: Glorinda water & wastewater technical profile.
Applications
Where it is used
Wherever water quality is a production variable rather than a utility.
Industries
- Power generation — demineralised water, boiler feed and condensate polishing
- Oil, gas and petrochemical — boiler feed, HRSG make-up and steam cycle chemistry
- Electronics and semiconductor — ultrapure water for wafer cleaning and rinse
- Pharmaceutical and biotech — purified water, WFI feed and clean steam
- Food and beverage — process water and boiler feed
- Chemical — process water where ions affect reaction chemistry
- Fertilizer — boiler feed and process water
- Textile and paper — boiler feed for drying and finishing
- Nuclear power plants — condensate polishing and demineralisation
Typical applications
- Industrial softening and demineralisation
- Condensate polishing
- Ultrapure water production
- Boiler feed water treatment
- Removal of harmful ions from irrigation water
- Potable water softening, PFAS removal and heavy metal trace removal
- Recovery of phenols, amines, organic acids and metals from wastewater
- Removal of organic compounds, colour and ammonia nitrogen to meet RO discharge standards
Equipment
Related products
Ion exchange resins
Over 200 types — cation, anion, mixed bed, chelating, adsorbent and chromatography media, with resin screening and process design support.
Read moreAnalyzer & metering systems
TOC, oil-in-water, pH, conductivity, dissolved oxygen and CEMS packages with sampling systems and shelters.
Read moreSteam turbines
50 kW to 180 MW plus energy recovery sets that convert surplus steam pressure into power.
Read moreLiquid ring vacuum pumps
Vacuum and compression duties across wastewater, chemical, paper and power applications, including explosion-protected models.
Read moreEngineering services
Engineering support for this technology
Selecting a process is an engineering decision, not a purchasing one. We run feasibility and pre-feasibility studies, characterise the stream, compare the routes on capital and operating cost, and act as owner's engineer while somebody else builds it if that suits you better.
Evidence
Projects
Sample layout. Reference projects are being cleared for publication with the clients concerned. The structure below is final; the content is placeholder.
SampleWater reuse retrofit — sample card
Card layout for a completed water reuse project: stream data before and after, recovery achieved, scope Glorinda held, and the client's own words.
SampleZLD package — sample card
Card layout for a zero liquid discharge package: feed characterisation, evaporator type selected, solid output route, and commissioning duration.
SampleOwner's engineer mandate — sample card
Card layout for an advisory mandate: the client's decision, the options assessed, and what changed in the tender as a result.
FAQ
Questions engineers ask
Taken from the questions procurement teams, plant managers and consultants actually send us.
EDI or mixed bed — which should we choose?
EDI if chemical handling is a problem, if space is tight, or if regeneration waste is a discharge issue; its initial investment is about 20% higher but operating costs and maintenance are lower. Mixed bed if capital cost dominates and you already have the acid and caustic infrastructure — but note that it generates hazardous waste liquids during regeneration and its operating costs run about 12.5% higher than EDI.
Which resins do you supply?
Over 200 types through Glorinda Resins: ion exchange (cation, anion, mixed bed), adsorbent resins, chelating resins, chromatography media, powder resins, solid phase peptide carriers, enzyme carriers and agarose medium. See the resin product page.
Can you help us choose the resin before we buy?
Yes — that is exactly what our technical service does. Experimental demonstrations, resin screening, process optimisation and troubleshooting, plus installation, commissioning and operator training.
How do you assure resin quality?
Through a defined QC programme: Mastersizer particle size analysis, specific surface area (SBET) and pore size determination, FTIR spectrometry, COD metering, Agilent HPLC, resin strength testing, moisture analysis, acid-base titration, AKTA purifier for protein purification and ICP for elemental analysis.
Do you supply the whole demineralisation train?
Yes. Pre-treatment, RO, EDI or mixed bed, storage, distribution and the instrumentation that monitors it — including conductivity, pH and TOC analysis.
Conversion
Take this further
Send us the stream data, the discharge limit or the equipment list you are working from. An engineer reads every enquiry and replies with the questions that actually decide the solution — not a brochure.