📋 Case Study

Wastewater Reclamation for Semiconductor Fab Using RO-NF Hybrid

High silica, boron, and trace metals (Cu, Ni) exceeding ultrapure water (UPW) specs (<0.1 ppb metals)

🏗️ Project Overview

300mm wafer fab in Arizona targeting 85% water reuse amid drought restrictions

🎯 Challenge

High silica, boron, and trace metals (Cu, Ni) exceeding ultrapure water (UPW) specs (<0.1 ppb metals)

🔧 Design Approach

Two-pass RO (first pass: BWRO, second pass: SWRO with pH adjustment), followed by NF polishing and electrodeionization (EDI); real-time ICP-MS feed monitoring

📐 Design Diagram

pH↑NFPolishingEDIFinal PolishingICP-MSReal-time feed monitoringChallengesSiO₂, B, Cu, NiLSI = −0.8B rejection = 92.3%

AI-generated project design illustration

📐 Key Calculations

Langelier Saturation Index (LSI)

pH − pHs

Result: −0.8

Predicts scaling propensity

Boron Rejection (RO)

1 − (C_perm/C_feed)

Result: 92.3%

Dictates need for NF polishing

📊 Results

91.4% reuse rate achieved; UPW resistivity >18.2 MΩ·cm; annual water cost savings: $2.7M

💡 Lessons Learned

• •NF stage required for boron polishing—RO alone insufficient
• •Silica scaling mitigated via antiscalant dosing + automatic CIP scheduling

✅ Key Takeaways

• 1NF stage required for boron polishing—RO alone insufficient
• 2Silica scaling mitigated via antiscalant dosing + automatic CIP scheduling