Ultrapure water equipment uses pretreatment, reverse osmosis technology, mixed beds, EDI devices, and post-treatment methods to remove almost all conductive media from water, as well as reduce colloidal substances, gases, and organic matter that do not dissociate in water to extremely low levels. It is also known as ultrapure water purifiers, ultrapure water machines, ultrapure water instruments, ultrapure water systems, laboratory ultrapure water purifiers, etc. The resistivity of ultrapure water produced by ultrapure water machines should generally exceed 10 MΩ·cm, and water above 10 MΩ·cm is called ultrapure water, with typical output reaching 18.25 MΩ·cm.
Reverse osmosis (RO) membrane technology
The equipment primarily adopts reverse osmosis (RO) membrane technology. Its working principle is to apply pressure to water, allowing water molecules and ionic mineral elements to pass through the RO membrane, while most dissolved inorganic salts (including heavy metals), organic matter, bacteria, viruses, etc., cannot penetrate the membrane. This strictly separates the purified water that permeates through from the concentrated water that does not. The RO membrane has pores as small as 0.0001 microns, while viruses typically have a diameter of 0.02–0.4 microns and common bacteria have a diameter of 0.4–1 micron.
EDI technology is a revolutionary water treatment technology that integrally combines electrodialysis with ion exchange for continuous demineralization, belonging to high-tech green environmental protection technology. EDI water purification equipment features continuous water output, no need for acid-alkali regeneration, and unattended operation, gradually replacing mixed beds as polishing treatment equipment in pure water systems.
EDI devices, applied after RO systems, replace ion exchange resins without acid-alkali regeneration, featuring stable water quality, low operation costs, convenient operation and management, and small floor space.
Parameter:
| Item | EDI | Mixed Bed |
| Product Water Quality | 15 - 18 MΩ·cm | 2 - 10 MΩ·cm |
| Stability | Stable water quality | Water quality is greatly affected by resin exchange status and regeneration quality |
| Operability | Simple operation, no need for professionally skilled workers | High requirement for operators' operation level during regeneration |
| Environmental Friendliness | No acids or alkalis needed, no chemical pollution at all | Acids and alkalis needed for regeneration, need to solve storage and discharge issues of acids and alkalis |
| Continuous Operation | No shutdown required during regeneration, regeneration while operating | Shutdown required for regeneration |
| Operation Cost | Low | High |
| Initial Investment | Relatively high | Low |
- Traditional process: composed of mechanical filters, activated carbon filters, and security filters.
- Latest process: composed of mechanical filters, security filters, and ultrafiltration (UF).
- Composed of high-pressure pumps and RO membranes.
- Can be divided into primary RO and secondary RO.
- Composed of ion exchange and microfiltration filters.
- Composed of EDI and microfiltration filters.
- Pretreatment System → RO System → Intermediate Water Tank → Coarse Mixed Bed → Fine Mixed Bed → Pure Water Tank → Pure Water Pump → UV Sterilizer → Polishing Mixed Bed → Precision Filter → Water Usage Object (≥18 MΩ·cm) (traditional process)
- Pretreatment → RO → Intermediate Water Tank → Water Pump → EDI Device → Purified Water Tank → Pure Water Pump → UV Sterilizer → Polishing Mixed Bed → 0.2 or 0.5μm Precision Filter → Water Usage Object (≥18 MΩ·cm) (latest process)
- Pretreatment → Primary RO → Dosing Machine (pH Adjustment) → Intermediate Water Tank → Secondary RO (Positive Charge RO Membrane) → Pure Water Tank → Pure Water Pump → EDI Device → UV Sterilizer → 0.2 or 0.5μm Precision Filter → Water Usage Object (≥17 MΩ·cm) (latest process)
- Pretreatment → RO → Intermediate Water Tank → Water Pump → EDI Device → Pure Water Tank → Pure Water Pump → UV Sterilizer → 0.2 or 0.5μm Precision Filter → Water Usage Object (≥15 MΩ·cm) (latest process)
- Pretreatment System → RO System → Intermediate Water Tank → Pure Water Pump → Coarse Mixed Bed → Fine Mixed Bed → UV Sterilizer → Precision Filter → Water Usage Object (≥15 MΩ·cm) (traditional process)
Each of the above processes has its advantages, and you can select a suitable process based on your specific needs. With scientific development, many new processes have replaced old ones, and RO technology for producing high-purity water has become popular and is the most current process.
- Large water permeability and high desalination rate, normally ≥98%.
- High interception and removal effect on organic matter, colloids, particles, bacteria, viruses, heat sources, etc.
- Low energy consumption, high water utilization rate, and lower operation costs than other desalination equipment.
- The separation process has no phase change, with reliable stability.
- Small equipment volume, simple operation, easy maintenance, strong adaptability, and long service life.
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