If enteric disease-causing protozoans have been found in the effluent of a water plant, which is the most probable solution?

• A. Increase chemical usage
• B. Use a multibarrier approach—coagulation, flocculation, sedimentation, and filtration
• C. Deploy UV treatment alone
• D. Reduce water temperature

Answer: (B)

The most probable solution when enteric disease-causing protozoans are found in the effluent of a water plant is to use a multibarrier approach, which includes coagulation, flocculation, sedimentation, and filtration. This comprehensive method is effective in addressing protozoan contamination because each step is designed to remove particles and pathogens from the water.

Coagulation is the process of adding chemicals that bind to suspended particles, making them larger and easier to remove. Flocculation follows, where these larger particles are agitated to encourage clumping, forming bigger flocs. Sedimentation allows these flocs to settle out of the water column due to gravity, effectively reducing the concentration of contaminants. Finally, filtration provides a physical barrier that can capture remaining particles and microorganisms, including protozoans that might have escaped earlier stages.

This multibarrier strategy is crucial because relying on a single method often does not provide adequate protection against varied and persistent pathogens like protozoans, which can be resistant to certain treatments. Using multiple layers of treatment ensures greater overall effectiveness in purifying water and safeguarding public health.