Mechanical Aeration: It is seen that in the diffused air framework, just a little percent of oxygen, not more than ten is really used in the oxidation procedure utilized as treatment for sewage, the rest, around 90%, is essentially required to realize the necessary fomentation of the sewage ooze blend. A lot of oxygen is constantly acquired from the environment at the surface. The realization of this reality has offered ascend to mechanical air circulation, in which the sewage is continually blended by mechanical methods so as to carry it into personal contact with the air. This being progressively conservative and profitable is as a rule progressively followed in present day rehearses utilized as treatment for sewage. Two sorts of sewage air circulation frameworks are regularly utilized.

• Paddle instruments
• Spray instruments

Oar Mechanisms

Paddle instruments flow the sewage in the xu ly nuoc thai y te air circulation tank. The last are comprised of long between associated channels with the end goal that the sewage needs to travel a significant distance. Oar wheels are set in an amazed manner or about vertical shafts in part lowered toward the finish of each pair of diverts in arrangement. Confounds are utilized to cause toppling movement. In this system, a piece of the sewage is additionally recycled to the influent end in the primary course of action. Subsequently, this is a superior strategy for treatment for sewage. The channels containing the oar instruments might be about 1.2 m profound x 1.8 m wide with paddle wheels plunging 20 to 30 cm into the sewage and spinning at 0.6 to 0.9 m/sec. Confinement periods for complete air circulation are to some degree longish 15 hours or much more for the air circulation of sewage.

Splash Mechanisms

In shower components, sewage is attracted to the surface and afterward tossed as flimsy sheets or movies on a superficial level. The film development helps in the assimilation of oxygen by uncovering enormous surface of sewage to the climate. The simplex framework is a notable case of this sort of treatment for sewage. This comprises of a solitary square container bottomed tank or a rectangular tank with a progression of square container bottomed units, through which sewage streams and which could possibly be furnished with confounds or separating dividers. Every unit has a focal take-up tube, which is augmented out at the base and has a reversed cone, suspended halfway at top concerning the take-up tube and driven by a component. The cone has vanes and during its transformations, sucks up sewage from the base and splashes it at the top, in this manner setting up a round movement in the sewage.