What three things does primary treatment help to remove to reduce the load on secondary treatment processes?

Primary treatment is a critical phase in wastewater treatment that serves the purpose of reducing the burden on secondary treatment processes. During primary treatment, physical processes such as sedimentation and screening are utilized to target specific contaminants found in wastewater.

The correct answer identifies the three key components that primary treatment effectively removes: Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), and Total Suspended Solids (TSS).

COD represents the total amount of oxygen required to oxidize both biodegradable and non-biodegradable organic matter in water, hence eliminating a substantial portion of organic pollutants. BOD is a measure of the amount of biodegradable material in the wastewater; reducing BOD in the primary stage helps decrease the potential for oxygen depletion in receiving waters and minimizes the load on biological treatment processes. TSS encompasses all solids that can be trapped by a filter; removing these solids is crucial for preventing clogging and operational issues in subsequent treatment phases.

By removing these three metrics, primary treatment ensures that secondary processes can operate more efficiently, focusing on the removal of remaining contaminants, thereby improving the overall effectiveness of the wastewater treatment system.