What does the term "activated sludge" refer to?

The term "activated sludge" specifically refers to a mixture of wastewater and microorganisms that undergoes a biological treatment process. During this process, microorganisms, including bacteria and protozoa, feed on organic matter present in the wastewater. This interaction helps to break down pollutants and improve the overall quality of the effluent.

The activated sludge process is a critical component in many wastewater treatment plants, as it relies on these microorganisms to remove contaminants from wastewater effectively. The aeration of this mixture allows for the growth and multiplication of microbes, creating a "floc" that can settle out of the treated water in a secondary clarifier, enabling a cleaner effluent to be discharged or further treated.

Understanding this concept is essential for recognizing how biological treatment works in the context of wastewater management and plant operations.