What is the primary goal of the secondary treatment process in wastewater treatment?

The primary goal of the secondary treatment process in wastewater treatment is to further reduce organic material. This stage typically follows primary treatment, which primarily focuses on physical processes to remove large solids. Secondary treatment is characterized by biological processes that utilize microorganisms to decompose organic matter present in the wastewater.

During this stage, the organic pollutants in the wastewater are converted into biomass, which can then be settled out or further processed. Key methods include activated sludge processes, trickling filters, and biofilm reactors, all of which foster conditions for microbial growth and metabolism, effectively breaking down complex organic compounds into simpler, less harmful substances.

Reducing organic material is essential to minimizing the biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of the treated effluent, crucial for meeting environmental discharge standards and protecting water quality. This significant reduction helps to ensure that the treated water is safe for release back into the environment or for reuse in certain applications.