Here is the professional English translation of the RO membrane process for metal ion removal in the new energy industry:

I. Application Scenarios & Objectives

1. Typical Wastewater Streams
   • Lithium battery manufacturing: Electrode slurry rinse water (Li, Co, Ni, Mn ions)
   • PV cell production: Silicon wafer cutting wastewater (Ag⁺, Cu²⁺)
   • Metal recovery: Leachate from spent batteries
2. Key Targets
   • Metal ion rejection ≥99% (e.g., Ni²⁺, Co²⁺, Li⁺)
   • Product water conductivity <20 μS/cm (reusable in production)
   • 5-10× concentration of valuable metals for resource recovery
   • Compliance with Battery Industry Pollutant Discharge Standards (GB 30484)

II. Process Design ("Staged Purification + RO" Integrated System)

graph LR  
    A[High Metal-Ion Wastewater] --> B[Pretreatment Unit]  
    B --> C[Primary RO System]  
    C --> D1[Product Water → Reuse/Discharge]  
    C -->|Concentrate| D[Secondary Concentration Unit]  
    D --> E1[Resource Recovery]  
    D --> E2[Secondary Reduction]  

III. Core Process Details

1. Pretreatment Unit (RO Membrane Protection)

Critical Parameters: SDI₃₀ <3, TOC <0.5 mg/L, Fe/Mn <0.05 mg/L

2. RO Membrane System (Core Separation Barrier)

• Membrane Selection: High-rejection antifouling RO membranes (e.g., Dupont Filmtec™ FR series, Li⁺ rejection >98%)
• Configuration:
  • Primary RO: 2:1 staging (75% recovery)
  • Secondary RO (for concentrate): SWRO membranes (>15 bar, 50% recovery)
• Rejection Performance:

  Ion Type	Target Rejection
  Ni²⁺/Co²⁺	>99.8%
  Li⁺	98-99.5%
  Cu²⁺/Ag⁺	>99.9%
  SO₄²⁻/Cl⁻	>99%

3. Concentrate Resource Recovery

• Electrolytic Recovery: High-purity Cu/Ni/Ag recovery (current efficiency ≥85%)
• Selective Precipitation:
  • Li⁺ → Battery-grade Li₂CO₃ (via Na₂CO₃ addition)
  • Co²⁺/Ni²⁺ → Metal sulfides (via Na₂S precipitation)
• MVR Evaporation Crystallization: Industrial-grade salt production (e.g., Na₂SO₄)

IV. Key Equipment List

V. Technical Advantages & Economics

1. Innovations
   • Membrane Surface Modification: Hydrophilic coating reduces metal ion adsorption fouling
   • Pulse Flush Mode (Patent-Pending): Mitigates concentration polarization
   • AI Optimization: Antiscalant dosage prediction based on water quality analytics
2. Cost Comparison

   Treatment Method	Cost (USD/ton)	Metal Recovery Value
   Conventional Chemical	3.5-5.5	None
   RO Membrane System	1.7-2.5	Co/Ni recovery >USD 110k/year (1,000 tons/day scale)

VI. Critical Considerations

1. Membrane Fouling Control
   • Weekly CIP (pH2 acid wash + pH12 alkaline wash)
   • Pre-install oil removal unit for oil-containing streams
2. Concentrate Corrosivity
   • Hastelloy pumps/valves required for secondary RO
3. Fluoride Risk Management
   • Add activated alumina adsorption unit if F⁻ >10 mg/L

Industry Case: Ternary precursor manufacturing plant results after implementation:

• Ni/Co rejection: 99.92%
• Product water reused in cooling systems (conductivity ≤15 μS/cm)
• Annual metal recovery value: RMB 6.2 million (USD 850k)

Mechanism of Metal Ion Rejection by RO Membranes

[Feed Side] Metal ions + H₂O → [RO Membrane]  
          ↑ Charge repulsion / Size exclusion ↓  
[Permeate Side] H₂O + Trace ions  
[Concentrate Side] 5-8× concentrated metal ions