Which of the following practices is least effective in treating wastewater?

Direct discharge to water bodies is the least effective practice in treating wastewater because this approach typically involves releasing untreated or inadequately treated wastewater directly into rivers, lakes, or oceans. This can lead to significant environmental issues, including pollution, harm to aquatic life, and contamination of drinking water sources. Effective wastewater treatment is essential to reduce harmful substances, nutrients, and pathogens before water is returned to the natural environment.

In contrast, methods like activated sludge, composting toilets, and septic systems are designed to treat wastewater effectively. Activated sludge systems involve biological processes to break down organic matter efficiently, while composting toilets focus on safe sanitation and resource recovery by composting human waste. Septic systems treat wastewater on-site, utilizing a combination of physical, biological, and chemical processes to cleanse water before it percolates into the ground. These practices are specifically engineered to minimize the environmental impact and ensure that effluent is safe for reuse or natural discharge.