The primary material for MBBR media is high-density polyethylene (HDPE) or polypropylene (PP). Manufacturers often use virgin (non-recycled) polymers to ensure durability and a long lifespan, which can be over 15 years. To enhance the media's functionality, a specific formula of additives is blended with the polymer. These additives can include:
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UV inhibitors: To protect the media from degradation when exposed to sunlight.
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Hydrophilic agents: These make the media more "water-loving," which encourages the rapid and stable attachment of microorganisms to the surface.
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Trace elements: Fused into the polymer to promote the quick adhesion and growth of the microbial biofilm.
The raw polymer pellets and additives are mixed thoroughly to create a uniform material before extrusion.