A step in the sewage treatment process in which a part of the decomposer bacteria present in the wastes is recycle back into the biological treatment process:
A step in the sewage treatment process in which a part of the decomposer bacteria present in the wastes is recycle back into the biological treatment process:
The correct option is B Activated sludge treatment
In the sewage treatment plant once the BOD levels of partially treated sewage effluent drops to a sufficiently low level, a second sedimentation process is carried out in a settling tank. In the secondary sedimentation the solid or bacterial floc is separated from the liquid. The separated solid floc is called a secondary or activated sludge. A small part of this activated sludge is used as an inoculum of decomposing bacteria and is pumped back into the secondary or biological treatment phase. After the activated sludge is separated from the effluent, the nutritionally and microbially poor liquid portion of the sewage is suitable for release into the environment without causing danger to aquatic lifeforms.
Activated sludge treatment
In the sewage treatment plant once the BOD levels of partially treated sewage effluent drops to a sufficiently low level, a second sedimentation process is carried out in a settling tank. In the secondary sedimentation the solid or bacterial floc is separated from the liquid. The separated solid floc is called a secondary or activated sludge. A small part of this activated sludge is used as an inoculum of decomposing bacteria and is pumped back into the secondary or biological treatment phase. After the activated sludge is separated from the effluent, the nutritionally and microbially poor liquid portion of the sewage is suitable for release into the environment without causing danger to aquatic lifeforms.
