MBR Membrane Module Aeration Coil Tube — Stainless Steel Perforated Coil Pipe
Product Overview
The MBR Membrane Module Aeration Coil Tube is a specialized stainless steel perforated coil pipe engineered for use within Membrane Bioreactor (MBR) systems in advanced wastewater treatment facilities. This product serves as the critical aeration distribution element within MBR membrane assemblies, delivering uniform air flow to maintain membrane flux, prevent fouling, and support biological treatment processes. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this coil tube is designed to withstand the aggressive chemical environment encountered during membrane cleaning cycles involving activated sludge and sodium hypochlorite (NaClO) solutions.
Unlike conventional aeration systems, the MBR membrane module aeration coil tube integrates directly into the membrane module housing, providing distributed, bubble-free aeration that minimizes shear stress on membrane surfaces while ensuring consistent transmembrane pressure (TMP) management. The perforated design ensures even air distribution along the entire coil length, reducing localized clogging risks associated with biofilm accumulation and particulate deposition.
Material & Properties
The aeration coil tube is fabricated from two primary stainless steel grades, selected based on the severity of the service environment:
- ASTM A270 / ASTM A269 Grade 304 (UNS S30408) — Suitable for standard MBR applications with moderate chlorine exposure. Offers excellent general corrosion resistance, good weldability, and a cost-effective balance of mechanical properties. Maximum recommended NaClO concentration: 200 ppm (free chlorine).
- ASTM A270 / ASTM A269 Grade 316L (UNS S31603) — Recommended for aggressive environments involving elevated sodium hypochlorite concentrations, high-chloride influents, or industrial wastewater streams. The addition of 2–3% molybdenum (Mo) significantly enhances resistance to pitting and crevice corrosion. Maximum recommended NaClO concentration: 500 ppm (free chlorine).
Key Material Properties:
- Resistance to biofilm adhesion due to low surface roughness (Ra ≤ 0.4 μm after finishing)
- Chemical stability in alkaline environments (pH 6–12) typical of activated sludge systems
- Non-toxic, non-leaching composition compliant with potable water contact standards
- Long-term mechanical integrity under cyclic pressure loading (aeration pulsation)
Specifications
| Parameter | Specification |
|---|---|
| Product Category | Coil Tube (盘管) — Perforated Aeration Type |
| Application Classification | Environmental Water Treatment → Wastewater Treatment → MBR Membrane Module |
| Material Grade | 304 Stainless Steel (UNS S30408) / 316L Stainless Steel (UNS S31603) |
| Outer Diameter (OD) | 12 mm – 25 mm (customizable per membrane module design) |
| Wall Thickness | 0.8 mm – 1.5 mm |
| Perforation Diameter | 0.5 mm – 1.5 mm (uniform distribution, tolerance ±0.05 mm) |
| Perforation Pitch (Center-to-Center) | 3 mm – 8 mm (staggered pattern) |
| Perforation Density | 100 – 300 holes per meter (configurable) |
| Coil Diameter | 50 mm – 200 mm (spiral winding) |
| Coil Length | 1 m – 10 m (continuous coil) |
| Surface Finish | Electropolished (Ra ≤ 0.4 μm) or Passivated (ASTM A967) |
| Operating Pressure | 0.1 – 0.5 MPa (aeration side) |
| Operating Temperature | 5 °C – 60 °C |
| Design Features | Backflush port integration; anti-clogging perforation geometry; uniform hole distribution |
| Connection Type | Threaded, flanged, or quick-connect fittings (per module specification) |
| Standards Compliance | ASTM A270 / A269, EN 10217, GB/T 12771 |
Manufacturing Process
The production of MBR membrane module aeration coil tubes follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, perforation uniformity, and corrosion resistance:
- Material Selection & Inspection — Certified 304 or 316L stainless steel seamless tube (ASTM A269) is procured with full mill test certificates (MTC). Incoming material undergoes spectroscopic verification (PMI) to confirm alloy composition.
- Cold Drawing & Sizing — The tube is cold-drawn to precise OD and wall thickness tolerances (±0.05 mm), ensuring consistent perforation performance along the entire length.
- Perforation (Punching) — High-precision CNC-controlled perforation is executed using hardened tungsten carbide tooling. The staggered hole pattern is programmed to ensure uniform air distribution with zero overlapping holes. Hole diameter uniformity is maintained within ±0.05 mm tolerance.
- Coil Forming (Coiling) — The perforated tube is cold-coiled using a precision coiling machine to achieve the specified spiral diameter and pitch. Springback compensation algorithms ensure dimensional accuracy of the final coil geometry.
- Welding & Connection Fabrication — End connections (inlet/outlet ports) are TIG-welded (GTAW) using ER308L or ER316L filler wire, followed by back-purging with argon to prevent internal oxidation.
- Electropolishing & Passivation — The finished coil tube undergoes electropolishing to remove surface contaminants, refine grain structure, and achieve Ra ≤ 0.4 μm surface roughness. This is followed by chemical passivation per ASTM A967 to form a protective chromium oxide layer.
- Quality Control & Testing — Each batch undergoes: pressure testing (1.5× working pressure, 30-minute hold), helium leak detection, dimensional inspection, and visual examination of perforation integrity.
Applications
The MBR membrane module aeration coil tube is deployed in a wide range of wastewater treatment and water reclamation applications:
- Municipal Wastewater Treatment — Primary aeration element in hollow-fiber and flat-sheet MBR membrane modules for municipal sewage treatment plants, providing controlled air scouring to prevent membrane fouling.
- Industrial Wastewater Reclamation — Used in pharmaceutical, food & beverage, textile, and chemical industry effluent treatment systems where high-quality effluent is required for recycling or discharge compliance.
- MBR Skid-Mounted & Containerized Systems — Compact coil tube designs are integrated into modular, transportable MBR units for decentralized wastewater treatment at remote sites.
- Advanced Oxidation Process (AOP) Integration — Compatible with hybrid systems combining MBR with ozonation or UV-AOP, where the coil tube withstands intermittent oxidant exposure.
- Activated Sludge + MBR Hybrid Systems — Designed to handle the dual challenge of biological solids (activated sludge) and chemical cleaning agents (sodium hypochlorite at 200–500 ppm) during routine membrane cleaning cycles.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management and compliance certifications to ensure product reliability:
- ISO 9001:2015 — Quality Management System certification covering design, manufacturing, and quality assurance processes
- ISO 14001:2015 — Environmental Management System certification
- CE Marking — Conformity with European Union directives for industrial equipment
- Material Traceability — Full lot traceability with EN 10204 Type 3.1 mill certificates for every production batch
- NACE/AMPP Compliance — Corrosion resistance testing aligned with industry best practices for chlorinated environments
- NSF/ANSI 61 — Water quality standards compliance (where applicable for potable water reclamation configurations)
Unique Selling Points
Engineered for the Harshest MBR Environments
- Superior Hole Uniformity: CNC-precision perforation with ±0.05 mm tolerance ensures consistent bubble size and air distribution, directly translating to stable membrane flux and reduced energy consumption. Non-uniform holes are the primary cause of localized membrane fouling — this design eliminates that failure mode.
- Integrated Backflush Design: The coil tube incorporates dedicated backflush ports that enable reverse-flow cleaning cycles without disassembly, dramatically reducing maintenance downtime and extending service life between membrane replacements.
- 316L Option for Chlorine Resistance: The availability of 316L grade with molybdenum alloying provides exceptional resistance to sodium hypochlorite cleaning solutions (up to 500 ppm), addressing the most common degradation mechanism in MBR aeration systems.
- Electropolished Surface: Ra ≤ 0.4 μm finish minimizes biofilm nucleation sites, reducing organic fouling accumulation and extending the interval between chemical cleaning cycles (CIP — Clean-In-Place).
- Customizable Geometry: Coil diameter, length, perforation pattern, and connection types are fully configurable to match specific membrane module designs (hollow-fiber, plate-and-frame, or flat-sheet configurations).
Technical Notes & Recommendations
- For applications involving sodium hypochlorite cleaning at concentrations exceeding 200 ppm, 316L grade is strongly recommended to prevent intergranular corrosion and pitting.
- Regular inspection of perforation integrity is advised every 6–12 months, particularly in high-solids influent conditions where particulate clogging risk is elevated.
- Backflush cycles should be scheduled in conjunction with membrane cleaning protocols to maintain optimal aeration uniformity throughout the coil tube length.
- Storage and handling should avoid contact with carbon steel tools or materials to prevent galvanic corrosion and iron contamination of the passive film.