Which process typically follows the primary treatment stage in wastewater treatment?

The primary treatment stage in wastewater treatment primarily involves the physical removal of large solids and sediments through processes such as sedimentation and screening. After this initial stage, biological treatment generally follows to further reduce the organic matter and pollutants remaining in the wastewater.

Biological treatment utilizes microorganisms to break down organic materials in the wastewater. This stage is crucial for the degradation of substances that primary treatment alone cannot effectively remove. The process can take place in different forms, such as activated sludge systems or trickling filters, where bacteria consume organic materials, resulting in less pollution and improved water quality.

While filtration, chemical treatment, and disinfection are also important steps in wastewater treatment, they typically occur either during or after biological treatment rather than directly following primary treatment. Filtration often serves to remove remaining particulate matter, chemical treatment is used for additional pollutant removal and disinfection is used as a final step to kill pathogens before the effluent is released. Therefore, the sequential flow from primary treatment to biological treatment is vital in ensuring comprehensive treatment of wastewater.