Comprehensive Guide to MBR Membrane Technology: Structural Principles & Practical Applications

1. MBR Technology Overview

The Membrane Bioreactor (MBR) represents a revolutionary advancement in 21st-century wastewater treatment, integrating biological processing with membrane filtration to achieve effluent quality surpassing conventional activated sludge methods. According to IWA statistics, global MBR adoption in municipal wastewater treatment has grown from 8% (2010) to 34% (2023), driven by four key innovations:

✔ ‌Dual-Barrier Filtration‌: 0.1μm pores eliminate suspended solids/microorganisms
✔ ‌MLSS Revolution‌: 8,000-12,000 mg/L sludge concentration (vs. 3,000-5,000 mg/L traditional)
✔ ‌Premium Effluent Quality‌: Turbidity <0.2 NTU, COD <30 mg/L (direct reuse compliant)
✔ ‌Space Efficiency‌: 50%+ footprint reduction


2. MBR Membrane Classification System

2.1 By Filtration Precision

2.2 By Configuration

‌Flat Sheet Modules‌

• Construction: Polypropylene support + PVDF membrane

• Advantages: Fouling resistance, offline cleaning capability

• Case: Kubota modules in 100,000 m³/day municipal project (Japan)

‌Hollow Fiber Membranes‌

• Dimensions: 1-3mm OD/0.5-1mm ID

• Configuration: Curtain/Bundle arrangement

• Example: MEMSTAR SMM-1520

‌Tubular Membranes‌

• Specifications: Ø5-15mm × 1-3m length

• Application: High-strength organic wastewater (e.g., landfill leachate)

2.3 By Material Composition

3. MBR Membrane Structural Analysis

SEM imaging reveals four-layer architecture in PVDF hollow fiber membranes:

1. ‌Support Layer‌ (200μm): Polyester non-woven (Tensile >100 MPa)

2. ‌Transition Layer‌ (50μm): Macroporous structure (80-85% porosity)

3. ‌Separation Layer‌ (20μm): Finger-like pore structure (0.1μm pores)

4. ‌Surface Layer‌ (0.5μm): Hydrophilic coating (PEG grafted)

Key Parameters:

textCopy CodePorosity: 60-85%  
Tensile Strength: ≥5 MPa  
Pure Water Flux: ≥500 L/(m²·h·bar)

4. Determinants of MBR Membrane Lifespan

4.1 Influent Quality Management

• COD Load: <8,000 mg/L (requires equalization tank)

• Oil Content: <30 mg/L (needs DAF pretreatment)

• SS Concentration: <100 mg/L

4.2 Operational Parameters

• Aeration Intensity: 0.8-1.2 m³/(m²·h)

• Suction Cycle: 8min ON/2min OFF or 7min ON/1min OFF

• MLSS Maintenance: 8,000-12,000 mg/L

4.3 Fouling Control

• Irreversible Fouling: Weekly chemical cleaning

• Biofouling: Monthly NaOCl soak (200-500 ppm)

5. MBR Operation & Maintenance Protocol

5.1 Daily Operation

1. Pre-start Checklist: >90% aeration uniformity

2. TMP Monitoring: Alarm at >0.25 MPa

3. Online Cleaning:

• Standard: Backwash every 2hr (0.15 MPa, 30s)

• Advanced: LongClear™ membranes (no backwash required, extended offline cleaning cycles)

5.2 Professional Cleaning Methods

6. MBR Technology Applications

6.1 Municipal WWTPs

• Beijing Huaifang Plant (600,000 m³/day): Meets Class IV surface water standards

6.2 Industrial Applications

• Petrochemical WWT: COD reduction from 2,000→50 mg/L

6.3 Emerging Uses

• Medical Wastewater: >99.99% COVID-19 inactivation

• Decentralized Systems: Grade 1A effluent in rural areas