MEMBRANES

Diffusers may get more credit, but the gap that separates a successful plant from an ecological nightmare may be thinner than you think.

OUR MEMBRANES’ CHEMISTRY KEEPS THE PHYSICS OF BUBBLES WORKING TO OPTIMIZE YOUR PLANTS’ BIOLOGY.

Like shoes, there are no one-size-fits-all membranes. Membranes shape bubbles and protect diffusers amidst some of the harshest forms of wastewater humans have contrived. Well-made, reliable membranes reduce replacement times and ensure oxygen transfer meets expectations; and thanks to EDI engineering, you have the right membrane that will allow your plant to perform according to expectations, for as long as you expect.   

We have our own membrane lab at our Columbia, MO facility; some employees affectionately call it our “Institute of Membrane Technology.” Apart from regularly testing the field performance of our own membranes and actively formulating new membrane materials to ensure plant operators and engineers have the membrane to meet every unique need, our membrane lab facility  is well equipped to test Dynamic Wet Pressure (DWP)Active Area / Uniformity, and Physical and Material Properties (DimensionalTensile and ElongationTear StrengthExtractSpecific GravityFlex FatigueTension and Compression SetHeat Shrink / Mass Age Loss etc.) as applicable for various membrane materials 

The composition of a membrane determines its resistance to heat, resilience in the face of harsh contaminants, and resulting long-term durability. Applying linear perforations using precision instruments allows the membrane to reseal after bubble release, preventing fouling while creating uniform bubble size and ensure even distribution of air across the entire surface of the membrane. Our rigorous sourcing, manufacturing, testing, and quality control procedures ensure your membranes work exactly as intended at your plant.

EDI Membranes

Advantages:

Formulated to suit unique applications
Perforation in the U.S.A.
Engineered by EDI aeration experts  Wide variety of material options

Compatibility:

Diffusers:

FlexAir® Pro fine-bubble disc, tube, panel, and Streamline™ diffusers
FlexAir® Basic fine-bubble 9-inch solvent-welded disc diffusers

Configurations:

Fixed Grid
ModuleAir™ Retrievable

Applications:

Municipal Wastewater
Industrial Wastewater

What membranes deliver

Wastewater can contain various types of aggressive substances and conditions

which can attack and degrade any material, including membranes.

Especially in industrial applications it is important to choose the correct membrane material to ensure a long operating lifespan of diffuser membranes. Choosing the correct perforation pattern is also important. Each family of perforations  (NanoPore, MicroPore, and High Capacity) has an ideal operating range in which they are designed to operate at their optimum capacity.

Want to know which membrane is right for your application?

Our on-staff professional engineers can help you select the right membrane material and perforation based on the max continuous operating condition and always meet your wastewater treatment requirements. 

Our membranes are made to fit your treatment needs.

The below table shows a comparison between the membrane types and their typical use cases.

 

EPDM
PTFE-Coated EPDM
Standard Polyurethane
High-Temperature Polyurethane (HTPU)
Matrix™
Matrix Plus™
Silicone Specialty Polymers
Applications:
  • Light mix of industrial influent
  • All domestic waste
  • Oil & gas
  • Food processing
  • Animal byproducts
  • All domestic waste
  • High mix of industrial influent
  • Improved pressure stability
  • All domestic waste
  • Municipal waste
  • Tanneries
  • Breweries
  • On/Off Applications
  • Performance guaranteed
  • Pulp & Paper
  • Improved Pressure
  • Stability
  • All domestic waste
Temperature Rating: Up to 115°C (240°F) Standard PU: up to 70°C (160°F)
HTPU: up to 80°C (180°F)
Matrix: up to 85°C (190°F)
Matrix Plus: up to 95°C (200°F)
up to 110°C (230°F) Varies
Available for:
FlexAir Pro disc diffusers

FlexAir Pro tube diffusers

FlexAir Pro panel diffusers

FlexAir Basic disc diffusers

EPDM & PTFE-Coated EPDM

Property Material Tests

Hardness Shore A 55 +/-5
Specific Gravity < 1.20
Tensile Strength, psi >9.0 MPa
Tensile Modulus, @100% elongation > 1.03 MPa
Tensile Modulus, @300% elongation > 2.93 MPa
Ultimate Elongation > 400%
Tear Strength, Die T 6.1 kN/m
Surface Ozone Cracking Resistance @50 ppm Non Cracking
Low Temperature @ -40°C Non Brittle
Extractable Oil Content < 15%

Property Material Tests

Hardness Shore A 55 +/-5
Specific Gravity < 1.20
Tensile Strength, psi > 1300 psi
Tensile Modulus, @100% elongation > 150 psi
Tensile Modulus, @300% elongation > 425 psi
Ultimate Elongation > 400%
Tear Strength, Die T > 35 lbf/in
Surface Ozone Cracking Resistance @50 ppm Non Cracking
Low Temperature @ -40°C Non Brittle
Extractable Oil Content < 15%

Property Material Tests

Hardness Shore A 58 +/-5
Specific Gravity < 1.20
Tensile Strength, psi > 7.9 MPa
Tensile Modulus, @100% elongation > 1.55 MPa
Tensile Modulus, @300% elongation > 3.79 MPa
Ultimate Elongation > 400%
Tear Strength, Die T > 7 kN/m
Surface Ozone Cracking Resistance @50 ppm Non Cracking
Low Temperature @ -40°C Non Brittle
Extractable Oil Content < 25%

Property Material Tests

Hardness Shore A 58 +/-5
Specific Gravity < 1.20
Tensile Strength, psi >1150 psi
Tensile Modulus, @100% elongation > 225 psi
Tensile Modulus, @300% elongation > 550 psi
Ultimate Elongation > 400%
Tear Strength, Die T > 40 lbf/in
Surface Ozone Cracking Resistance @50 ppm Non Cracking
Low Temperature @ -40°C Non Brittle
Extractable Oil Content < 25%

EPDM & PTFE-COATED EPDM

Ethylene Propylene Diene Monomer

Available for FlexAir Pro tube, disc, and panel diffusers, as well as FlexAir Basic disc diffusers
• Temperature resistance up to 240ºF (115 °C)
• Chemical resistance for municipal and most industrial applications
• PTFE coating technology available for specialized applications
• UV protection incorporated in the compound
• Low dynamic wet pressure
• Low oil construction for membrane stability
• No inorganic fillers for maximum performance
• High concentration of polymers for superior service

SILICONE MEMBRANE MATERIAL

Polymer for Specialty Applications

Property Material Tests

Hardness Shore A 60 +/-5
Specific Gravity <1.25
Tensile Strength, psi >9.0 MPa
Tensile Modulus, @100% elongation 2.69 +/- 0.28 MPa
Ultimate Elongation > 400%
Tear Strength, Die T >10.5 kN/m
Surface Ozone Cracking Resistance @50 ppm Non Cracking
Low Temperature @ -40°C Non Brittle

Property Material Tests

Hardness Shore A 60 +/-5
Specific Gravity < 1.25
Tensile Strength, psi > 1300 psi
Tensile Modulus, @100% elongation 390 +/-40 psi
Ultimate Elongation > 400%
Tear Strength, Die T >60 lbf/in
Surface Ozone Cracking Resistance @50 ppm Non Cracking
Low Temperature @ -40°C Non Brittle

Property Material Tests

Hardness Shore A 58 +/- 5
Specific Gravity < 1.20
Tensile Strength, psi > 7.9 MPa
Tensile Modulus, @100% elongation 1.38 +/- 0.34 MPa
Ultimate Elongation > 600%
Tear Strength, Die T >12 kN/m
Surface Ozone Cracking Resistance @50 ppm Non Cracking
Low Temperature @ -40°C Non Brittle

Property Material Tests

Hardness Shore A 58 +/-5
Specific Gravity < 1.20
Tensile Strength, psi >1150 psi
Tensile Modulus, @100% elongation > 225 psi
Ultimate Elongation > 600%
Tear Strength, Die T >70 lbf/in
Surface Ozone Cracking Resistance @50 ppm Non Cracking
Low Temperature @ -40°C Non Brittle

Material Features

• High temperature resistance up to 350 °F (177 °C)
• Excellent uniformity and distribution of released air bubbles
• Formulated for application specific condition
• Good chemical compatibility in most municipal and industrial application
• Available for tube and disc diffusers
• UV protection inherent in the compound
• Low dynamic wet pressure (DWP)
Note: Not recommended for some ON/OFF applications

STANDARD AND HIGH-TEMPERATURE POLYURETHANE

Property Material Tests

Hardness Shore A 85 +/- 5 Shore A
Specific Gravity <1.15
Tensile Strength >24.1 MPa
Tensile Modulus, @100% elongation >4.72 MPa
Tensile Modulus, @300% elongation >8.27 MPa
Ultimate Elongation >475%
Tear Strength, Die T >26 kN/m

Property Material Tests

Hardness Shore A 85 +/- 5 Shore A
Specific Gravity <1.15
Tensile Strength >3500 psi
Tensile Modulus, @100% elongation >685 psi
Tensile Modulus, @300% elongation >1200 psi
Ultimate Elongation >475%
Tear Strength, Die T >150 lbf/in

Property Material Tests

Hardness Shore A 90 +/-5
Specific Gravity < 1.16
Tensile Strength > 34.5 MPa
Tensile Modulus, @100% elongation > 9.0 MPa
Tensile Modulus, @300% elongation > 20.7 MPa
Ultimate Elongation > 400 %
Tear Strength, Die T >26 kN/m

Property Material Tests

Hardness Shore A 90 +/-5
Specific Gravity < 1.16
Tensile Strength > 5000 psi
Tensile Modulus, @100% elongation > 1300 psi
Tensile Modulus, @300% elongation > 3000 psi
Ultimate Elongation > 400 %
Tear Strength, Die T > 150 lbf/in

PU + HTPU Membrane Material

Available for FlexAir Pro tube and panel diffusers
• Maximum mechanical strength and properties—will withstand harsh wastewater environments
• Smooth surface characteristics inhibit fouling and prevents build-up of bio-solids
• Excellent durability and chemical resistance
• UV protection to resist UV rays before start-up of the system

• long-term stability in DWP
• Tested with over 2 million on/off cycles
• No extractable oil content

PRODUCT SPECIFICATIONS

PU + HTPU Membrane Material
Polyurethane &
High Temperature Polyurethane
Polyurethane

MATRIX™ AND MATRIX PLUS™

Property Material Tests

Hardness Shore A 74 +/-5
Specific Gravity 1.21 g/cm³
Tensile Strength >12.4 MPa
Tensile Modulus, @100% elongation >3.45 MPa
Tensile Modulus, @300% elongation >8.27 MPa
Ultimate Elongation >350%
Tear Strength, Die T >10.5 kN/m

Property Material Tests

Hardness Shore A 74 +/-5
Specific Gravity 1.21 g/cm³
Tensile Strength >1800 psi
Tensile Modulus, @100% elongation >500 psi
Tensile Modulus, @300% elongation >1200 psi
Ultimate Elongation >350%
Tear Strength, Die T >60 lbf/in

Property Material Tests

Hardness Shore A 88 ± 5 
Specific Gravity 1.15 g/cm³
Tensile Strength >24.1 MPa
Tensile Modulus, @100% elongation >4.72 MPa
Tensile Modulus, @300% elongation >8.27 MPa
Ultimate Elongation >475%
Tear Strength, Die T >26 kN/m

Property Material Tests

Hardness Shore A 88 ± 5
Specific Gravity <1.15 g/cm³
Tensile Strength >3500 psi
Tensile Modulus, @100% elongation >685 psi
Tensile Modulus, @300% elongation >1200 psi
Ultimate Elongation >475%
Tear Strength, Die T >150 lbf/in

Material Features

• Premium pure compounds for stability and long membrane life
• Fully PTFE impregnated top layer guaranteed to never wear off
• Provides membrane protection for outside (water side), and slit perforations.
• Dual Layer, high temperature inside layer, with co-extruded PTFE outer layer
• Strongest panel PU membrane material
• PTFE MATRIX™ Reduces organic and inorganic fouling.

MEMBRANES: FAQ

How to properly store a flexible membrane system post-installation and before system start-up?

If the reactor is drained and the aeration system is exposed for a short period of time (less than 4 weeks), the system shall be protected from foreign objects including but not limited to paint or weld splatter, falling objects, etc. If SDM saddle mounted diffusers are being installed during large temperature swings (20°-40°) The Wedges should be loosely installed prior to Start-Up. 

A gray fabric tarp should be suspended above the aeration system approximately 6” (150 mm) if the ambient air temperature is above 100°F (40°C). When the ambient conditions drop below 40˚F (4˚C) plastic aeration components may become brittle, protect the system from falling objects and other impacts by covering the system with 4 feet of clean water. If temperatures drop below 32˚F, the water must be deep enough to prevent ice from contacting the aeration system. If water must be added to the aeration basin when ice is present, ensure that no aeration components are encased in ice, before proceeding. Do not attempt to break aeration components free of any ice in the aeration basin. If the aeration system is idle for an extended period of time (greater than 4 weeks), the system should be submerged in approximately 4 feet of clean water provided the ambient air temperature is greater than 32°F (0°C). If the ambient air temperature is below 32°F (0°C), the water level may need to be increased so that the ice layer does not contact the aeration system. 

When reactivating a system where ice exists, operate the system at a minimum airflow to avoid movement of ice and maintain this airflow condition until the ice is no longer present. The water level should never be lowered if ice is present. The weight of the ice may damage the system.  

Warning: Do not use any form of plastic to cover the aeration components. Plastic can create a hotter environment and/or fuse to the surface of the equipment. 

Does membrane cleaning improve diffuser performance?

It’s easy to improve aeration diffuser performance and efficiency while reducing your plant’s carbon footprint.  

Diffusers are made to last a long time. Without regular cleaning; fouling may result in a loss of effectiveness of the aeration system. Symptoms of which may include permit violations, increased back pressure on your blowers with corresponding increase in energy consumption, and/or Dissolved Oxygen (DO) levels go down. 

Make Diffuser Cleaning part of your yearly maintenance!  

SiteWorks has the tools and the expertise to evaluate and clean your aeration system in a timely and cost effective manner. No need to dewater your tanks, or stop treatment—no downtime. Depending on the number of diffusers, proper diffuser cleaning can reduce energy cost by over 25%. 

When to use acid cleaning for membranes and how effective is that method?

When standard cleaning methods do not produce desired results, inorganic scaling may be present and may require an alternate cleaning technique. Inorganic scaling is a granular mineral-like precipitate that can form on the membrane surface. 

The foulant adhered to a membrane can be tested with a solution of muriatic acid (20° Baume Hydrochloric Acid, 31.45% by weight HCl) for reactivity. This may indicate the nature of the foulant and its propensity for chemical cleaning. Ensure that the air supply has been turned off from the diffusers being serviced. Afterwards, place a small amount of acid on the surface of the membrane where fouling is most prevalent. If the foulant is reactive to acid, this is indicative of inorganic fouling, such as calcium deposits, and acid cleaning is recommended. Otherwise, the foulant is typically organic and acid cleaning may not prove effective. 

If it is determined that the foulant does respond to acid, the membrane may be cleaned with acid in addition to manual cleaning. This technique involves applying Muriatic Acid directly to the membrane surface after the manual cleaning procedure followed by rinsing with a low-pressure hose. In the case of ceramic diffusers, the acid is typically applied both on the surface and pumped through the diffuser using air. 

Note: EDI can provide an acid injection system, upon request, for cleaning aeration systems without process interruptions. Contact EDI for more information. 

Warning: Read all applicable SDS (Safety Data Sheets) carefully and follow all instructions given therein. Always have new users familiarize themselves with the SDS before handling chemicals. Wear personal protective equipment (including, but not limited to, rubber gloves, safety goggles, and other protective clothing) as required. 

Which chemicals are compatible to clean the membranes in my system?

The diffuser membranes should be protected from chemicals that may be harmful to the material. If using a cleaning aid or other substance on or around the membranes, please contact EDI for chemical compatibility.