Which of the following is NOT a method for metals removal from wastewater?

Activated biological processes primarily focus on the removal of organic matter and nutrients such as nitrogen and phosphorus from wastewater. These processes, such as activated sludge systems, rely on microorganisms to decompose organic pollutants. While they are effective for treating biological material, they do not specifically target the removal of metal contaminants.

In contrast, methods such as hydroxide precipitation involve adding chemicals to the wastewater that react with metal ions to form insoluble compounds, which can then be removed through sedimentation. Ion exchange utilizes resin materials to specifically absorb metal ions from the water, effectively reducing their concentration. Evaporation can concentrate wastewater, potentially facilitating metal recovery, although it is not the most common method for direct metal removal.

Understanding the appropriate methods for treating different types of contaminants is essential in wastewater management, as each technique is designed for specific purposes and pollutant removal.