California Wastewater Treatment Operator Practice Exam 2025 – All-in-One Guide to Master Your Certification

The process that relies primarily on the presence of oxygen in wastewater treatment is aerobic treatment processes. These processes utilize aerobic microorganisms, which require oxygen to break down organic matter in the wastewater. When oxygen is present, these microorganisms can effectively metabolize the waste products, converting them into carbon dioxide, water, and biomass. This method is highly efficient for treating sewage and organic waste, making it a common choice in many wastewater treatment facilities.

Aerobic treatment is critical for reducing biochemical oxygen demand (BOD), which is a measure of the organic pollutants in the water. By using oxygen as part of the metabolic process, these systems promote the growth of beneficial bacteria that can degrade contaminants, resulting in cleaner effluent that can be discharged or further treated for reuse.

In contrast, the other processes mentioned do not primarily depend on the presence of oxygen. Fermentation processes occur in the absence of oxygen and rely on anaerobic bacteria to break down organic material, while anaerobic treatment processes also function without oxygen and typically produce biogas as a byproduct. Filtration processes are physical methods used to separate solids from liquids and do not involve biological processes dependent on oxygen.