Question

Sequentially arrange the stepwise process of wastewater treatment: 

A. Primary sedimentation 
B. Screening and Grit removal 
C. Disinfection 
D. Secondary treatment unit and Secondary Sedimentation 
Choose the most appropriate answer from the options given below:

• A. B, A, C, D
• B. A, C, B, D
• C. B, A, D, C
• D. C, B, D, A

Hint:

Wastewater treatment sequence is always: Preliminary → Primary → Secondary → Tertiary (disinfection).

Answer 1

The Correct Option is C

Step 1: Preliminary Treatment (Screening and Grit Removal).
This initial phase involves screening and grit removal (B).

Step 2: Primary Sedimentation.
Settleable solids are removed, and suspended matter is reduced (A).

Step 3: Secondary Treatment and Sedimentation.
Biological treatment is performed, followed by secondary sedimentation to eliminate biomass (D).

Step 4: Disinfection.
Prior to disposal or reuse, the treated wastewater is disinfected (C).

Step 5: Summary.
The proper order is B → A → D → C. The correct option is (C).