The following processes are used in wastewater treatment. Match the stage of treatment with the processes. Each choice can be used once, more than once, or not at all.
<IMAGE>

Verified step by step guidance

1. Identify the main stages of wastewater treatment: primary, secondary, and tertiary treatment.
2. Understand the purpose of each stage: primary treatment involves physical processes, secondary treatment involves biological processes, and tertiary treatment involves chemical or advanced processes.
3. List the processes shown in the image and categorize them based on their nature: physical, biological, or chemical.
4. Match each process to the appropriate stage of treatment based on its characteristics and purpose.
5. Review the matches to ensure each process is correctly aligned with the stage of treatment it supports.

Key Concepts

Wastewater Treatment Stages

Wastewater treatment typically involves three main stages: primary, secondary, and tertiary treatment. Primary treatment focuses on the physical removal of solids through sedimentation. Secondary treatment employs biological processes to degrade organic matter, while tertiary treatment further polishes the effluent, often removing nutrients and pathogens to meet regulatory standards.

Biological Treatment Processes

Biological treatment processes are crucial in the secondary stage of wastewater treatment. These processes utilize microorganisms to break down organic pollutants. Common methods include activated sludge systems and biofilm reactors, where bacteria metabolize organic matter, converting it into biomass and simpler compounds, thus reducing the biochemical oxygen demand (BOD) of the wastewater.

Nutrient Removal

Nutrient removal is an essential aspect of tertiary wastewater treatment, aimed at reducing nitrogen and phosphorus levels to prevent eutrophication in receiving water bodies. Techniques such as chemical precipitation, biological nutrient removal (BNR), and advanced filtration are employed to achieve low nutrient concentrations, ensuring that treated water is safe for discharge or reuse.