The mechanism of sewage treatment is that microorganisms decompose organic matter in sewage to purify the water. Supplying air to the microorganisms stimulates their activity and promotes the decomposition of organic compound. Treatment methods for sewage can be broadly divided into the activated sludge method and the biomembrane method. When using activated sludge method, microorganisms are suspended in water, while microorganisms are attached to specific membrane when using the second method.

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The membrane aerated bioreactor (MABR) method is a type of bioreactor and differs from the membrane bioreactor (MBR) method. MBR method is a type of activated sludge method that uses a membrane to separate treated water and sludge. On the other hand, the MABR method uses membranes to supply oxygen to biological membranes settled on the membrane surface.

One of the advantages of the MABR method is the high utilization of  oxygen .The MBR method does not require constant aeration (air supply to the water) as in the MBR method. Because of this advantage, the MABR method is attracting attention as a treatment method that helps save energy. Silicone rubber and polyolefin porous hollow fiber membranes are often used as membranes.

　In addition, the use of oxygen-enriched microorganism-attached carriers, in which silicone hollow fibers are coated with fine polyester fibers, enables removal of organic matter, digestion, and denitrification without the need for multiple stages of equipment. This treatment system is expected to provide more advanced wastewater treatment.

One example is a silicone hollow fiber surrounded by a film of super fine polyester fibers. Polyester fibers are carriers for microorganisms, and nitrification proceeds inside the microbial membrane due to the high concentration of oxygen. On the other hand, outside, the high concentration of organic matter causes decomposition of organic matter. Therefore, organic matter removal, digestion, and denitrification can be performed without the need for multiple stages of equipment.