Civil Engineering - Waste Water Engineering - Discussion

Method => Contact Mechanism => Decomposition.
.
1. Trickling filter => Attached growth=> Aerobic.
2. Rotating biological contactor => Attached growth => Aerobic.
3. Activated sludge process => Suspended growth => Aerobic.
4. Oxidation pond => Suspended growth => Aerobic.
5. Septic tank => Suspended growth => Anaerobic.
6. Imhoff tank => Suspended growth => Anaerobic

ASP is a suspended growth aerobic process.

A trickling filter is an attached growth aerobic process.

Imhoff tank has dual character (ie) aerobic in nature in the upper portion and anaerobic in the lower portion.

So, none of these is the correct option.

Here, it should be "aerobic" not anaerobic.

The correct option is A".

Option (a) Imhoff tank is the correct option.

Explanation.

A trickling filter is a type of wastewater treatment system. It consists of a fixed bed of rocks, coke, gravel, slag, polyurethane foam, sphagnum peat moss, ceramic, or plastic media over which sewage or other wastewater flows downward and causes a layer of microbial slime (biofilm) to grow, covering the bed of media. Aerobic conditions are maintained by splashing, diffusion, and either by forced-air flowing through the bed or natural convection of air if the filter medium is porous.

In Imhoff tank, there are two parts.

1. Sedimentation takes place, which is exposed to the atmosphere i.e. aerobic.

2. Digestion tank which is not exposed to air i.e anareobic.

Sludge digestion tanks work only in anaerobic condition. So C should be the right answer.

Trickling filter, oxidation ponds, RBCs are based on an aerobic process whereas Septic tanks, imhoff tanks sludge digestion tanks, and anaerobic lagoons are based on the anaerobic process.

The right answer is A mode of decomposition in Trickling Filter is Aerobic while imhoff has anerobic.

C is the correct answer.

It should be imhoff tanks because the remaining three works on the principle of Aerobic decomposition.