The hardness removal system removes calcium and magnesium ions from water through chemical softening, ion exchange, or membrane separation, reducing water hardness and scaling tendency and providing stable feed conditions for reverse osmosis, evaporative crystallization, and heat exchange systems.
Process Principle
- Chemical softening: dosing lime, soda ash, or sodium hydroxide to precipitate calcium and magnesium as carbonates and hydroxides, followed by separation.
- Ion exchange: using sodium-form or hydrogen-form resin to replace calcium and magnesium ions, achieving a low effluent hardness level.
- Membrane softening: using nanofiltration to reject divalent ions, providing a softening path that does not generate large amounts of chemical sludge.
Product Features
- It effectively reduces the scaling risk of downstream membrane systems and evaporators and extends cleaning cycles and equipment life.
- Chemical softening and membrane softening can be combined to balance removal efficiency and sludge reduction.
- Chemical dosing and reaction conditions can be flexibly adjusted according to influent hardness and alkalinity.
- Connects with pretreatment units such as MBR and ultrafiltration to form a complete front-end zero liquid discharge (ZLD) process.
Application Industries
- Softening treatment for high-hardness groundwater and circulating cooling water.
- Feed pretreatment for reverse osmosis and evaporative crystallization systems.
- Boiler make-up water preparation for the power, chemical, and metallurgical industries.
- Front-end hardness reduction and salt separation pretreatment in zero liquid discharge projects.
Specifications and Models
| Parameter | Unit | Typical value |
|---|---|---|
| Treatment scale | m³/h | 5–500 (typical) |
| Total hardness of effluent (chemical method) | mg/L (as CaCO₃) | 50–150 (typical) |
| Total hardness of effluent (ion exchange) | mg/L (as CaCO₃) | ≤ 10 (typical) |
| Calcium ion removal rate | % | 85–98 (typical) |
| Reaction time | min | 15–40 (typical) |
| Sludge solids content | % | 2–5 (typical value) |
The data in the table are common ranges for similar equipment and are for selection reference only; specific specifications, models, materials, connections, and control methods must be confirmed during the selection stage based on water quality, treatment scale, and site conditions.