Environmental engineering Q3 Choose the correet answers 1 Ae

Environmental engineering

Q3:. Choose the correet answers 1) Aera tion in activated sludge processes is used to: a) Prevent settling of solids in the reactor b) Provide treated water with oxygen c) Cause homogenization of sewage in the reactor d) All of the above 2) The main objective of secondary treatment is to remove a) suspended solids c) microorganisms b) soluble organics d) Non of the above 3) The function of recirculation in activated sludge system is: a) Increase the concentration of microorganisms in reactor b) Increase the F/M ratio c) Decrease the F/M ratio d) a and b 4) if the depth of an oxidation pond is 1.5 m, then the pond classified as: a) aerobic pond c) Facultative pond b) anaerobic pond d) b and c

Solution

1) Option C is correct. It causes homogenization of sewage in the reactor and helps micro oranism to get more food and get settled in the following sedimentation process.

2)Option B is correct. It removes the soluble organics. Primary treatment removes suspended solids and disinfection removes micro organisms.

3) Option D is correct. It increase the concentration of micro organisms as the dead micro organism will be returned and increase the F/M ratio.

4)Option C is correct. If depth is 1 to 2 m it is facultative pond. If less than 1 meter it is aerobic and if more then two meters it is anerobic.