Since the first installation in 1995, the superior mechanical properties of the RAUBIOXON Plus silicone membrane and polypropylene support pipe air distribution systems have shown excellent resistance to wear under varied (industrial and municipal) wastewater applications, delivering extended useful service life.
Short service life of ethylene propylene diene monomer (EPDM)-type membranes has been attributed to the deterioration of the physical properties of the membrane, due to leaching out of plasticiser (mineral oils), incrustation of the membrane via growth of biological slime and/or calcium carbonate or magnesium oxide precipitates.
After assessing the failure modes and effects of previous products and applications, REHAU developed the RAUBIOXON Plus diffused aerators with the following features:
• RAU-SIK silicone membranes are an inorganic, homogeneous silicone rubber that contains no plasticiser, and therefore does not harden or become brittle over time, maintaining its original mechanical properties
• the silicone compound is a hydrophobic material, and as a result, has little affinity for deposits
• to mitigate growth of biological substances on the membrane, REHAU developed and patented an anti-microbial formulation with heavy metal inhibitors extruded through the membrane surface
• RAU-SIK silicone membrane is highly resistant to temperature (-80 degrees Celsius to 200 degrees Celsius), oil and grease, and most inorganic and organic chemicals.
The polypropylene supports pipe and air distribution systems is approximately double the wall thickness of commonly used polyvinyl chloride (PVC) pipework, and is distinguished by its rigidity and hardness. It also has excellent toughness and abrasion resistance compared to other thermoplastics, and was specifically chosen to suit the expected longer service life of the silicone membrane.
The ability for RAUBIOXON Plus to maintain its mechanical properties over time, and its little affinity for deposits, means that it not only has a high initial oxygen transfer efficiency (OTE), but that it also maintains this efficiency over time. It is commonly accepted that increases in diffuser back pressure are correlated with a reduction in OTE, due to fouling or changes in mechanical properties or aerator membranes.
Rehau RAUBIOXON Plus fine bubble pipe aerators have shown to:
• minimise back pressure over the life cycle of the aerator, reducing plant energy consumption
• save on installation costs, because less pipe work and less diffusers elements are needed
• reduce maintenance costs, as the patented RAU-SIK membrane provides high resistance to microbial encrustation, maintains elasticity for longer and is ultraviolet (UV) stable.
If you consider the back pressure testing conducted by Sydney Water at its West Hornsby wastewater treatment plant, it is evident that the RAUBIOXON Plus diffuser is wearing at a significantly slower rate than the existing EPDM design, which suggests a considerably longer service life. After only three years, there is an approximate five kilopascal difference between the EPDM and RAUBIOXON designs, which relates to 10–15 per cent extra blower power consumption.
This comprehensive testing under Australian conditions clearly shows the superior performance of the RAUBIOXIN Plus silicone membrane.
Whether you are upgrading, refurbishing, building a new plant or simply looking for ways to improve your plant operations, REHAU has the customised solution.
Contact us now on 1800 MORE 02, or email us at to receive more information and get your free design.