Active sludge process is the type of wastewater treatment process that uses aeration and biological flocs to treat wastewater or industrial wastewater. This process involves the use of microorganisms to break down organic matter in the wastewater, resulting in the removal of pollutants and the production of treated effluent that can be safely discharged into the environment.

The active sludge process consists of several key components and steps:

1. Aeration Tank: This is the main component of the process where the wastewater is mixed with activated sludge, which is a mixture of microorganisms such as bacteria and fungi. The aeration tank is equipped with diffusers or mechanical aerators that introduce air into the tank, providing oxygen for the microorganisms to carry out their metabolic activities.

2. Biological Flocs: The microorganisms in the activated sludge form biological flocs, which are agglomerates of cells and organic matter. These flocs help in the settling and separation of solid particles from the treated wastewater.

3. Aeration: The aeration process introduces oxygen into the wastewater, promoting the growth and activity of aerobic microorganisms. These microorganisms use the organic matter present in the wastewater as a food source, breaking it down into simpler compounds such as carbon dioxide, water, and biomass.

4. Settling Tank: After the aeration process, the wastewater flows into a settling tank, also known as a clarifier or sedimentation tank. In this tank, the biological flocs settle to the bottom due to gravity, forming a sludge layer called activated sludge. The clarified water, or effluent, is collected and removed from the tank.

5. Sludge Treatment: The activated sludge collected in the settling tank is further treated to remove excess water and stabilize it before disposal or reuse. This can involve processes such as thickening, dewatering, and digestion.

The active sludge process is widely used in wastewater treatment plants due to its effectiveness in removing organic matter, nutrients, and other pollutants from wastewater. The aeration and biological flocs help in providing the necessary conditions for microbial growth and activity, resulting in the degradation and removal of contaminants. This process can be customized and optimized based on the specific characteristics of the wastewater being treated, ensuring efficient and reliable treatment.