Basic Wastewater Operator Practice Exam 2025 – Comprehensive Prep

Following primary treatment in a wastewater treatment facility, secondary treatment is the next stage in the treatment process. Primary treatment primarily involves the physical separation of solids from wastewater, resulting in the removal of larger particles and organic matter through processes such as screening and sedimentation. However, while this initial treatment process eliminates a portion of the contaminants, it does not sufficiently reduce many dissolved organic materials and pathogens.

Secondary treatment builds upon the work of primary treatment by employing biological processes to further break down organic matter. This is commonly achieved through methods like activated sludge, trickling filters, or bio-filtration, where microorganisms consume the remaining organic material in the wastewater. This phase is crucial, as it significantly reduces the biochemical oxygen demand (BOD) and helps to ensure that the wastewater is treated to a higher degree before moving on to subsequent processes.

The steps that come after secondary treatment, such as tertiary treatment and disinfection, focus on further polishing the effluent by removing nutrients, pathogens, and any remaining contaminants to meet discharge standards or for potential reuse. However, secondary treatment is the essential next step that follows primary treatment in the wastewater treatment process.