Civil Engineering - Waste Water Engineering - Discussion

Discussion Forum : Waste Water Engineering - Section 7 (Q.No. 7)
The sewage treatment units in which anaerobic decomposition of organic matter is used, are called
imhoff tanks
trickling filters
sludge sedimentation tanks
none of these.
Answer: Option
No answer description is available. Let's discuss.
36 comments Page 1 of 4.

BUETK said:   2 months ago
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

Liaqat said:   7 months ago
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.

Jamahali said:   7 months ago
Here, it should be "aerobic" not anaerobic.

Engr khan said:   11 months ago
The correct option is A".

MUHAMMAD NABI said:   12 months ago
Option (a) Imhoff tank is the correct option.


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.

MJM said:   2 years ago
Sludge digestion tanks work only in anaerobic condition. So C should be the right answer.

Nirakar said:   2 years ago
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.

Atif Muneer Sakhani said:   2 years ago
The right answer is A mode of decomposition in Trickling Filter is Aerobic while imhoff has anerobic.

Sanku said:   2 years ago
C is the correct answer.

Mirwais kakar said:   2 years ago
It should be imhoff tanks because the remaining three works on the principle of Aerobic decomposition.

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