Ultrapure Water Solution for PV Silicon Wafer & Solar Cell Cleaning (Ultrafiltration Pre-treatment + Two-stage RO + EDI)

1. Project Overview

Application Scenario: Precision cleaning processes including monocrystalline/polycrystalline silicon cutting, texturing and etching, meeting core requirements of electronic-grade high-purity water.

Design Water Capacity: 20 m³/h; raw water is groundwater with high hardness and trace boron elements.

Outlet Water Standard: Resistivity ≥ 17.5 MΩ·cm, TOC ＜ 10 ppb, boron ions ＜ 5 ppb, turbidity ＜ 0.01 NTU.

Process Route: Enhanced Pretreatment Ultrafiltration (UF)→Two-stage Reverse Osmosis (RO)→EDI→Terminal Polishing Treatment.

2. Process Details

Enhanced pretreatment + ultrafiltration: Submerged ultrafiltration modules are configured against high turbidity risks of groundwater, with front-end interception of colloids and microorganisms to stably control RO influent SDI within 2.

First-stage RO + boron-specific second-stage RO: Low boron rejection dedicated membrane elements are adopted, with front-end pH dosing adjustment to eliminate carbonate interference, targeting the pain point of boron ion pollution in PV industry water.

EDI deep ion removal: Eliminates residual trace salts and borides in water for further water purification.

254 nm UV sterilization + 0.01 μm terminal filtration: Inhibits biofilm growth in pipelines and intercepts ultra-fine particles, ensuring no watermarks or particle defects after silicon wafer cleaning and improving finished product yield.

3. Supporting Operation

The system can be linked with the DCS control system of the PV plant to automatically adjust water production flow according to peak and valley water loads of the workshop. RO concentrated water is directionally recycled for silicon wafer cutting waste flushing and plant ground cleaning, with comprehensive water resource utilization rate reaching 88%. Membrane elements support online acid and alkali chemical cleaning, adapting to complex working conditions affected by acid and alkali tail gas and wastewater cross-contamination in PV workshops.