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: Screening and Grit removal.
The first step in wastewater treatment is preliminary treatment, which involves screening and grit removal (B).

Step 2: Primary sedimentation.
This removes settleable solids and reduces suspended matter (A).

Step 3: Secondary treatment and secondary sedimentation.
Biological treatment is applied next, followed by secondary sedimentation to remove biomass (D).

Step 4: Disinfection.
Finally, treated wastewater undergoes disinfection before disposal or reuse (C).

Step 5: Conclusion.
Thus, the correct sequence is B → A → D → C. Correct answer is (C).