UPSC CMS PSM - Environmental Health & Sanitation

The usual indicator organism for recent faecal contamination of drinking water is:

Consider the following statements:

1. In the context of the question, “Clostridium tetani” is the most appropriate conclusion.
2. E. coli is abundant in human and animal faeces and should not be detected in a 100-mL sample of water intended for drinking.

Which of the statements given above is/are correct?

Breakpoint chlorination is reached when:

Consider the following statements:

1. Before the breakpoint, chlorine reacts with reducing substances and ammonia. Beyond it, a measurable free residual is available for disinfection.
2. In the context of the question, “All chlorine has evaporated” is the most appropriate conclusion.
3. In the context of the question, “Chlorine demand is satisfied and free residual chlorine begins to appear” is the most appropriate conclusion.

Which of the statements given above is/are correct?

A public-health team is investigating an environmental hazard and planning source control.

Biochemical oxygen demand is a measure of:

Select the single best answer.

The key purpose of sedimentation in water treatment is to:

Consider the following statements:

1. Sedimentation, often aided by coagulation, reduces turbidity and microbial load before filtration and disinfection.
2. In the context of the question, “Remove all dissolved salts” is the most appropriate conclusion.

Which of the statements given above is/are correct?

Slow sand filtration relies importantly on:

Consider the following statements:

1. In the context of the question, “High-pressure membranes only” is the most appropriate conclusion.
2. The schmutzdecke contributes biological removal while the sand bed provides physical filtration; cleaning is performed by scraping the surface.

Which of the statements given above is/are correct?