MBBR (Moving Bed Biofilm Reactor) media are designed to provide a large surface area for biofilm growth in wastewater treatment systems. The materials used to manufacture MBBR media are selected based on their durability, chemical resistance, and ability to support biofilm development. The most commonly used materials include:

1. High-Density Polyethylene (HDPE): HDPE is widely used for MBBR media due to its excellent chemical resistance, strength, and flexibility. It's resistant to a wide range of chemicals and has a low risk of degradation in various wastewater environments. HDPE is also relatively lightweight, which ensures good media movement within the reactor.

2. Polypropylene (PP): Similar to HDPE, polypropylene offers great chemical resistance and durability. It has a higher melting point than HDPE, making it suitable for applications where the media might be exposed to higher temperatures. PP is also resistant to bacterial growth, making it an ideal choice for MBBR media.

3. Polyvinyl Chloride (PVC): PVC is sometimes used for MBBR media, especially in applications where cost is a significant consideration. While PVC has good chemical resistance, it is generally less favored compared to HDPE and PP due to its lower resistance to UV light and potential environmental concerns associated with its lifecycle.

4. Expanded Polystyrene (EPS): Although less common, EPS can be used for MBBR media in specific applications. It is very lightweight, which can be advantageous for aeration and mixing within the reactor. However, its mechanical strength and chemical resistance are lower than those of HDPE and PP.

5. Recycled Plastics: Some MBBR media are made from recycled plastics as a more sustainable option. These can include various types of polyethylene or polypropylene. The use of recycled materials can reduce the environmental impact of the media but requires careful quality control to ensure the media meet the necessary standards for wastewater treatment.

When selecting MBBR media, it's essential to consider not only the material but also the specific design of the media, such as surface area, shape, and porosity. These factors influence the media's effectiveness in supporting biofilm growth and its overall performance in the wastewater treatment process.