Continuous electrodeionization stacks that polish RO permeate to ultrapure water with no acid or caustic regeneration. Replaces mixed-bed ion exchange, eliminating regeneration wastewater and neutralization tanks. For pharmaceutical, electronics, power and dialysis water.
Electrodeionization (EDI) polishes reverse osmosis permeate into ultrapure water without acid or caustic regeneration. It combines ion exchange resin, ion-selective membranes and a DC electrical field: the resin captures the residual ions that RO leaves behind, and the electrical field continuously drives them out through the membranes to a waste stream, regenerating the resin in place. The result is a continuous, chemical-free process that replaces the mixed-bed ion exchange columns traditionally used for final polishing — and eliminates the acid and caustic handling, neutralization tanks and regeneration wastewater that came with them.
EDI modules are built as a stack of alternating dilute and concentrate compartments separated by cation- and anion-selective membranes, with the dilute compartments filled with mixed ion exchange resin. RO permeate enters the dilute compartments, where residual dissolved ions are adsorbed onto the resin. A DC voltage applied across the stack pulls cations toward the cathode and anions toward the anode; each ion migrates through its corresponding selective membrane into an adjacent concentrate compartment, where it is swept away by a reject stream. Because the electrical field simultaneously splits a small amount of water into hydrogen and hydroxide ions, the resin is continuously regenerated in situ. The process therefore runs indefinitely without the exhaust-and-regenerate cycle that defines conventional ion exchange.
| Item | Detail |
|---|---|
| Process | Continuous electrodeionization — ion exchange resin, ion-selective membranes and DC field |
| Position in Train | Downstream polishing stage after reverse osmosis |
| Required Feed | RO permeate; feed quality determines achievable product resistivity |
| Chemical Regeneration | None — resin regenerated electrically in situ |
| Construction | Modular plate-and-frame stack; multiple module sizes available |
| Integration | Available as an EDI membrane group within the KJ-BWRO and industrial RO platforms |
| Sizing | Module count and stack configuration selected against required flow and target resistivity |
EDI performance is governed by the quality of the RO permeate feeding it, so stacks are specified against your RO output analysis and target water quality rather than sold from a fixed capacity list. Send your RO permeate conductivity and required product resistivity for a configured proposal.
EDI is unforgiving of a poorly specified RO stage in front of it. Feed the stack permeate with too much hardness or carbon dioxide and it will scale or lose resistivity, and no amount of adjustment downstream will recover it. HydropureWater specifies EDI as part of the complete train — pretreatment, RO, degassing where required, and the EDI stack sized against the actual permeate it will receive — rather than selling a module and leaving the interface to chance. Where you already have an RO plant, we will assess its permeate quality before quoting a stack.
Both polish RO permeate to ultrapure quality, but mixed-bed resin must be taken offline and regenerated with acid and caustic when exhausted, producing hazardous chemical handling and regeneration wastewater. EDI regenerates continuously using an electrical field, so it runs without interruption, without chemicals, and without a neutralization and waste treatment system.
Yes. EDI is a polishing technology, not a bulk desalination one. It is designed to remove the residual ions left in RO permeate. Feeding raw or partially treated water directly to an EDI stack will foul and scale it quickly.
EDI delivers ultrapure water suitable for pharmaceutical, electronics and power generation duty. The exact resistivity achievable depends on the quality of the RO permeate feeding the stack, which is why we size EDI against your specific RO output rather than quoting a universal figure.
Far less than ion exchange columns, since there is no regeneration cycle. Routine work is monitoring product resistivity and stack voltage, maintaining the upstream RO, and periodic cleaning if feed quality drifts. Stack life is measured in years when feed specification is respected.
Twin-tank industrial water softeners from 1 to 45 T/h with paired brine tanks from 60 to 2,000 L. Alternating vessels give uninterrupted soft water for boiler feed, cooling systems, laundries and RO pretreatment.
Complete turnkey bottled water lines integrating RO treatment, pure water storage, PET bottle blowing (350-1500 ml), 8-8-3 filling, labelling, inkjet coding and sleeve shrink packaging - specified as one balanced scope rather than separate machines.
Point-of-use direct drinking water systems for schools, offices, hospitals and factories - cabinet, floor-standing and under-counter purifiers plus portable water vending machines. Replaces bottled water delivery with treated mains water at the dispensing point.
WSZ series underground integrated sewage treatment plant combines anoxic/aerobic (A/O) biological contact oxidation with sedimentation and disinfection in a single buried package unit. Fully automated with no operator required, it handles 1–80 m³/h for residential communities, hotels, hospitals, factories, and rural areas. Can be installed below grade with landscaping above, or mounted on a trailer for mobile deployment.
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