What is the correct sequence, from initial to final, of surface waste water…
2025
What is the correct sequence, from initial to final, of surface waste water treatment?
A. Disinfection
B. Sedimentation
C. Filtration
D. Screening
Choose the correct answer from the options given below:
- A.
A, B, C, D
- B.
A, B, D, C
- C.
D, B, A, C
- D.
D, B, C, A
Attempted by 22 students.
Show answer & explanation
Correct answer: D
Correct sequence (initial to final): Screening → Sedimentation → Filtration → Disinfection.
Screening: removes large solids and debris at the intake to protect pumps and downstream units.
Sedimentation: allows settleable suspended solids to settle out by gravity (primary clarification).
Filtration: removes remaining fine suspended particles that were not settled in sedimentation.
Disinfection: final treatment step to inactivate pathogenic microorganisms before discharge or reuse.
Why this order matters:
Starting with screening protects downstream processes from damage and clogging.
Sedimentation reduces solids load, making filtration more effective and less frequent to maintain.
Disinfection is applied last because it is intended to treat the cleaned effluent; applying it earlier would be less effective if solids still remain.