Given below are two statements: Statement I: Screen chamber in wastewater…
2023
Given below are two statements:
Statement I: Screen chamber in wastewater treatment is used to remove small and heavy suspended solids.
Statement II: Grit chamber in wastewater treatment is used to remove large floating materials.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer: B. Both Statement I and Statement II are incorrect — ConceptPreliminary wastewater treatment separates solids by the physical mechanism a unit uses. Screening is interception by bars or mesh, whereas grit…
- A.
Both Statement I and Statement II are correct
- B.
Both Statement I and Statement II are incorrect
- C.
Statement I is correct but Statement II is incorrect
- D.
Statement I is incorrect but Statement II is correct
Show answer & explanation
Correct answer: B
Concept
Preliminary wastewater treatment separates solids by the physical mechanism a unit uses. Screening is interception by bars or mesh, whereas grit removal is sedimentation of dense inorganic particles.
Therefore, the material removed depends on size and settling behaviour: screens retain coarse floating or suspended matter, while grit chambers settle relatively small, heavy particles such as sand and grit.
Application
Statement I assigns small, heavy suspended solids to the screen chamber. That description belongs to grit removal, not bar or mesh screening, so Statement I is incorrect.
Statement II assigns large floating materials to the grit chamber. Those materials are intercepted by screens rather than settled as grit, so Statement II is incorrect.
Contrast and cross-check
“Both statements are correct” reverses the normal function of both units.
“Statement I is correct but Statement II is incorrect” retains the incorrect screen assignment.
“Statement I is incorrect but Statement II is correct” retains the incorrect grit-chamber assignment.
Hence, both Statement I and Statement II are incorrect.