In sewage treatment,what is removed by sedimentation?

$A$ very high concentration of $E. coli$ in water indicates $.........$

Which process is used to remove floating debris from sewage?

Biological process is carried out in which type of water treatment?

Select the correct sequence with respect to sewage treatment.
$i$. Removal of suspended solid particles by primary treatment.
$ii$. Wastewater screening
$iii$. Anaerobic bacteria digest activated sludge.
$iv$. Treatment by flocs in aeration tank.
$v$. Grit settling

The major contribution of bacteria in the carbon cycle includes ..........