Ontario Operator-in-Training (OIT) Practice Exam

What is the desired outcome of using lagoons in wastewater treatment?

1. Complete sterilization of wastewater

2. Reduction of biodegradable matter through physical processes

3. Promotion of chemical breakdown of pollutants

4. Quick turnover of treated water

The correct answer is: Reduction of biodegradable matter through physical processes

The desired outcome of using lagoons in wastewater treatment is primarily the reduction of biodegradable matter through physical processes. Lagoons are designed to allow for natural processes, including sedimentation and biological degradation, to occur over an extended period. In these systems, microorganisms consume organic matter in the wastewater, significantly reducing the levels of pollutants before the treated water is discharged or further processed. This method is particularly effective because it relies on natural processes that can enhance the breakdown of biodegradable material in an open environment. The design typically encourages settling of solids and enables aerobic and anaerobic conditions, which further aids in the degradation of organic matter. Other options such as complete sterilization, promotion of chemical breakdown, or quick turnover of treated water do not accurately describe the primary function of lagoons. Lagoons are not aimed at achieving complete sterilization, as that would require more advanced treatment methods. Rather, the focus is on reducing pollution to acceptable levels through biological and physical mechanisms over time.