What is the main goal of the secondary treatment process?

The main goal of the secondary treatment process is to further reduce biochemical oxygen demand (BOD) and suspended solids in wastewater. This stage occurs after primary treatment, where the larger solids are removed. During secondary treatment, biological methods, such as aeration and the use of microorganisms, are employed to break down organic matter, which is crucial in reducing the BOD of the water, making it less harmful to the environment upon disposal or reuse. Additionally, suspended solids are decreased significantly, leading to cleaner water that can meet regulatory standards for discharge.

Other options involve processes that do not accurately reflect the primary focus of secondary treatment. For example, collecting wastewater for storage is more about handling and managing the wastewater rather than treating it. Killing all microorganisms is not the objective; in fact, secondary treatment relies on these microorganisms to perform the necessary biological processes. Lastly, while nutrient removal can be a goal of certain advanced treatment processes, it is not the primary focus of secondary treatment as defined in typical wastewater management strategies.