The design of ' double-layer sound insulation cover + muffler duct ' is adopted, and the operating noise of high-speed fan is ≤ 65dB ( 20dB lower than that of traditional Roots fan ), which is equivalent to the normal conversation sound in the office. The bottom of the fuselage is equipped with damping pads, and the vibration amplitude is ≤ 1.5mm / s to avoid noise and vibration affecting the surrounding environment. It is used in sewage treatment stations near food factories, electronics factories and residential areas. It fully meets the environmental noise standards, does not disturb the people and does not affect production !