Ontario Operator-in-Training (OIT) Practice Exam

What is the primary function of lagoons in wastewater treatment?

1. To chemically treat wastewater

2. To stabilize organic matter and facilitate biological treatment

3. To filter solid waste particles

4. To enhance chlorination processes

The correct answer is: To stabilize organic matter and facilitate biological treatment

The primary function of lagoons in wastewater treatment is to stabilize organic matter and facilitate biological treatment. Lagoons, often referred to as stabilization ponds, provide a natural environment where microorganisms can break down organic matter present in wastewater. They utilize sunlight and natural aeration to enhance the growth of bacteria and other microorganisms that digest organic pollutants, thus leading to stabilization of the wastewater. As the wastewater flows through the lagoon, it experiences a combination of anaerobic and aerobic processes, enabling the effective treatment of various contaminants. The design and operation of these lagoons allow for the retention time needed for biological reactions to occur, resulting in significant reductions in biochemical oxygen demand (BOD) and organic load before the water is either reused or released into the environment. Other options do not accurately represent the primary function of lagoons. Chemical treatment, for instance, involves using chemicals to alter the composition of wastewater, which is not the basic function of lagoons. Similarly, while lagoons provide some filtering capability through sedimentation of solids, their main role is biological treatment rather than merely filtering. Enhancing chlorination processes pertains to disinfection methods that occur later in the treatment process, rather than something that lagoons do directly. Hence, the correct answer emphasizes that lagoons are essential