Why is sewage treatment important?

• A. It reduces pathogens, organic waste, nutrients, and pollution before water is released.
• B. It increases pathogens and pollution.
• C. It removes all water completely.
• D. It adds heavy metals to water.

Answer: (A)

The main idea is that treating sewage removes harmful contaminants before the water is returned to the environment or reused. Sewage contains disease-causing pathogens, organic matter that uses up oxygen as it decomposes, and nutrients like nitrogen and phosphorus that can fuel algae blooms. By applying mechanical, biological, and sometimes chemical processes, sewage treatment reduces these hazards: pathogens are killed or removed, organic waste is broken down, and nutrients are lowered so waterways don’t become oxygen-starved or over-enriched. This helps protect human health, preserve aquatic ecosystems, reduce odors, and ensure water supplies stay safe and usable.

Think about the alternatives in terms of goals. Increasing pathogens and pollution would be harmful, not the aim. Removing all water isn’t how treatment works—water is cleaned and released or reused, but not entirely eliminated. Adding heavy metals would introduce new pollutants, which is exactly what treatment seeks to prevent. The point of treatment is to cut contaminants and safeguard water quality, not to add new problems.