What is the primary role of disinfectants in tertiary sewage treatment?

What is the primary role of disinfectants in tertiary sewage treatment?

• A. They remove solids
• B. They reduce nutrients in water
• C. They kill bacteria
• D. They adjust pH to neutralize acidity

Answer: (C)

Disinfection in tertiary sewage treatment is about reducing health risks by killing pathogens. After solids have been removed and organic matter has been treated in earlier stages, the final polishing step uses disinfectants to inactivate remaining bacteria and other microorganisms before water is discharged or reused. This is different from removing solids (which happens in primary and secondary stages), removing nutrients (which requires nutrient-removal processes like denitrification or phosphorus precipitation), or adjusting pH (a chemical control for stability, not primarily aimed at pathogen destruction). So the key idea is that the disinfectant’s role is to kill bacteria and other pathogens to safe levels.

Disinfection in tertiary sewage treatment is about reducing health risks by killing pathogens. After solids have been removed and organic matter has been treated in earlier stages, the final polishing step uses disinfectants to inactivate remaining bacteria and other microorganisms before water is discharged or reused. This is different from removing solids (which happens in primary and secondary stages), removing nutrients (which requires nutrient-removal processes like denitrification or phosphorus precipitation), or adjusting pH (a chemical control for stability, not primarily aimed at pathogen destruction). So the key idea is that the disinfectant’s role is to kill bacteria and other pathogens to safe levels.