What does the activated sludge or biosolids process primarily control?

The activated sludge or biosolids process primarily focuses on controlling Biological Oxygen Demand (BOD). BOD is a critical parameter that measures the amount of oxygen that microorganisms will consume while decomposing organic matter in water. In wastewater treatment, especially within the activated sludge process, microorganisms are introduced to the incoming wastewater, where they break down organic pollutants and reduce BOD levels.

Effective control of BOD is vital because high levels of organic material can deplete oxygen in the receiving waters, harming aquatic life. The activated sludge process is designed to optimize the growth of these microorganisms, ensuring they efficiently process the organic waste. By maintaining the right conditions—such as aeration, which provides oxygen to the microorganisms and supports their metabolism—the system can effectively reduce BOD, leading to cleaner effluent when the treated water is released back into the environment.

While other factors like temperature, pH levels, and chemical concentrations can be important in the overall wastewater treatment process, they do not represent the primary focus of the activated sludge process, which is predominantly aimed at BOD reduction.