What Is Extended Aeration?

The aeration time ^[1] refers to the theoretical time when the mixed liquid treated with wastewater activated sludge is aerated in the aeration tank, usually expressed in hours. It is equal to the volume of the aeration tank divided by the volumetric flow of wastewater and returning sludge. In addition, the aeration time can also refer to the theoretical time for water to be aerated.

Aeration time

Aeration tank (aerationtank) is a device for aeration process in sewage biochemical treatment ^[3]

The main function of the aeration tank is to use activated sludge to remove pollutants in sewage. The volume is related to the inlet flow rate Q and the residence time in water (HRT). Q times HRT is the volume, which has no direct relationship with the aeration time. .

There are different calculation methods for the volume of the aeration tank, which are mainly calculated based on the hydraulic retention time (HRT) and the sludge load (MLSS) and the sludge age ((SRT)). The nature of the contaminant removal varies.

For example, when it is only required to remove carbon source pollutants, the latter two methods can be used. When the function of nitrogen and phosphorus removal needs to be considered, the formula of sludge concentration cannot be simply used. The influence of temperature on the rate of nitrogen removal must also be considered, and it must be determined in conjunction with the sludge yield. The endogenous respiratory attenuation of bacteria needs to be considered.

The aeration time is related to the water quality and drainage characteristics of wastewater. If it is domestic sewage, it can be used for 3 to 6 hours, and it can be industrial wastewater.

The aeration time refers to the theoretical time when the mixed liquid treated with wastewater activated sludge is aerated in the aeration tank, usually expressed in hours. It is equal to the volume of the aeration tank divided by the volumetric flow of wastewater and returning sludge. The main function of the aeration tank is to use activated sludge to remove pollutants in sewage. The volume is related to the inlet flow rate Q and the residence time in water (HRT). Q times HRT is the volume, which has no direct relationship with the aeration time. ^[1] .