Basic Wastewater Operator Practice Exam

Which process is used to remove phosphorus from wastewater?

1. Activated sludge process

2. Chemical precipitation

3. Nitrification

4. Denitrification

The correct answer is: Chemical precipitation

Chemical precipitation is a widely used method for removing phosphorus from wastewater. This process involves adding chemical agents, usually metal salts, such as aluminum sulfate or ferric chloride, to the wastewater. These chemicals react with the dissolved phosphorus to form insoluble precipitates that can then be removed through sedimentation or filtration. In the context of wastewater treatment, phosphorus removal is critical due to its role in promoting algal blooms in receiving waters, which can lead to water quality problems. By utilizing chemical precipitation, facilities can dramatically reduce the concentration of phosphorus, helping to meet regulatory discharge limits and protect aquatic ecosystems. The other processes mentioned, while important in their own right, are more focused on different aspects of wastewater treatment. The activated sludge process primarily addresses the removal of organic matter and excess nutrients, nitrification is concerned with the conversion of ammonia to nitrate, and denitrification involves the conversion of nitrate to nitrogen gas. None of these processes specifically target phosphorus removal as effectively as chemical precipitation does.