Key highlights: Things you may not know about disc diffusers

Standard Low-Profile EPDM (Ethylene Propylene Diene Monomer)

EPDM is a synthetic rubber compound developed in response to customer application requirements. Thanks to its unique formulation and compression molding process, this membrane retains its physical properties under minimal water pressure for extended periods. It is tear-resistant and maintains its shape after years of cyclic operation, producing fine, micro-sized bubbles.

Our EPDM membranes have been proven in various municipal and industrial wastewater treatment applications with excellent results. However, standard EPDM is not recommended for applications involving solvents, oils, greases, or high concentrations of metal salts.

PTFE (Polytetrafluoroethylene) and VITON®-Coated EPDM

PTFE and VITON® are synthetic rubbers commonly known as fluororubbers. They are recognized as high-performance materials due to their broad resistance to chemicals, solvents, oils, greases, and other substances that can damage conventional rubber. However, their primary drawback is high cost.

To address this, SSI has developed a fluororubber coating technology that permanently bonds these materials to the surface of EPDM or other substrate materials through a proprietary process—a method proven to be highly effective. This innovative technology enables the membrane to retain the excellent physical properties of traditional rubber while offering the chemical, solvent, and grease resistance found in the world's most advanced rubber materials—at an affordable cost.

Many wastewater treatment plants that had previously suffered from membrane damage caused by calcium scaling and solvent corrosion have demonstrated that SSI's new fluororubber-coated EPDM membranes experience neither fouling nor any alteration in material properties during use.

Silicone Rubber and Polyurethane

Prior to SSI's development of fluororubber-coated membranes, silicone rubber and polyurethane were the two primary material alternatives for wastewater treatment plants facing scaling issues or rubber oxidation caused by chemical solvents. Although SSI now manufactures silicone rubber and polyurethane membranes, we favor the comprehensive performance of fluororubber-coated membranes.

This is because silicone rubber and polyurethane tend to tear over time due to flex fatigue, whereas EPDM membranes are largely unaffected by this issue. Neither polyurethane nor silicone rubber is suitable for cyclic operation, nor are they more cost-effective than fluororubber-coated EPDM.