What type of bacteria are primarily used in secondary treatment of wastewater?

In the secondary treatment of wastewater, aerobic bacteria are primarily employed due to their role in the biological process of breaking down organic matter. These bacteria require oxygen to thrive and utilize it to decompose organic pollutants present in the wastewater. The presence of oxygen allows aerobic bacteria to efficiently metabolize organic substances, converting them into carbon dioxide, water, and new cellular material.

This process not only reduces the amount of organic matter and improves the quality of the effluent but also enhances the removal of nutrients, such as nitrogen and phosphorus, when coupled with additional treatment steps. Aerobic treatment processes can include methods such as activated sludge systems, trickling filters, and aerobic lagoons, all of which leverage the capabilities of aerobic bacteria to improve wastewater treatment efficiency.

While other types of bacteria, like anaerobic and facultative bacteria, also play roles in wastewater treatment—particularly in anaerobic digestion processes—the primary and most common use in secondary treatment predominantly involves aerobic bacteria. Pathogenic bacteria are typically a concern in wastewater but are not specifically utilized for treatment and are rather targeted for removal during the treatment process.