Activated sludge process is a widely used biological treatment method for sewage treatment. The following is an introduction to its principles and operating procedures:
principle
Microbial metabolism: Activated sludge contains a large number of microorganisms, mainly including bacteria, fungi, protozoa, and protozoa. These microorganisms feed on organic pollutants in wastewater, and through metabolic processes, break down organic matter into harmless substances such as carbon dioxide and water. At the same time, the microorganisms themselves can grow and reproduce.
Adsorption and flocculation of sludge: Activated sludge has good adsorption performance and can adsorb suspended particles, colloidal substances, and dissolved organic matter in sewage. In addition, microorganisms in the sludge secrete some viscous substances, which cause the sludge particles to aggregate and form larger flocs, facilitating sedimentation and separation.
operating procedure
Aeration tank:
Mixing of sewage and sludge: Pre treated sewage enters the aeration tank, while activated sludge returning from the secondary sedimentation tank is also sent into the aeration tank. Wastewater and activated sludge are thoroughly mixed in the aeration tank to form a mixed liquid.
Aeration oxygen supply: Air is introduced into the aeration tank through an aeration system to vigorously stir the mixed liquid, providing sufficient oxygen for microorganisms to meet their aerobic respiration needs; On the other hand, it ensures sufficient contact between sewage and activated sludge, promoting the adsorption and decomposition of organic matter by microorganisms.
Secondary sedimentation tank:
Solid liquid separation: After being treated in the aeration tank, the mixed liquid flows into the secondary sedimentation tank. Under the action of gravity, the activated sludge flocs settle to the bottom of the tank, and the clarified water overflows and is discharged from the upper part of the tank, achieving solid-liquid separation.
Sludge reflux and discharge: A portion of the activated sludge settled at the bottom of the tank is refluxed to the front end of the aeration tank through the sludge reflux system to maintain the concentration of activated sludge in the aeration tank; The other part is discharged as excess sludge to maintain the stable operation of the activated sludge system.
During the operation of activated sludge process, it is necessary to monitor and control some key parameters, such as dissolved oxygen, sludge concentration, sludge settling ratio, sludge volume index, etc., to ensure the treatment effect and stable operation of the system. At the same time, various process improvements and optimizations can be made to the activated sludge process according to different water quality and treatment requirements, such as traditional activated sludge process, stage aeration activated sludge process, fully mixed activated sludge process, oxidation ditch, etc.
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