The activated sludge process is a type of wastewater treatment process. The wastewater can be domestic or industrial. The activated sludge process uses aeration and biological flocs composed of bacteria and protozoa.
The general scheme of a process for the removal of carbonaceous impurities using activated sludge includes the following elements: An aero tank in which air (or oxygen) is injected into the mixture. This is followed by a settling tank (commonly referred to as a “final settling tank” or “secondary settling tank”) where biological flocs (sludge layers) can settle to separate the biological sludge from clean purified water.
In wastewater (or industrial) wastewater treatment plants, the activated sludge process is a biological process that can be used for one or more of the following purposes: Removal of nutrient substances (nitrogen and phosphorus).
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What is Activated Sludge?
It is defined as a “suspension” of living and dead microorganisms in wastewater. Microorganisms are activated by inhalation of air (oxygen) known as activated sludge. Activated sludge is sludge that is freely aerated and mixed with wastewater in the aeration tank and then settled in the secondary settling tank.
Process
This process uses aerobic microorganisms that digest organic matter in the wastewater and can stick to each other (by agglomeration). In this way, a liquid is obtained which is relatively free of suspended solids and organic matter as well as agglomerated particles that can be easily precipitated and removed.
A general plan for activated sludge for carbon decontamination includes:
- An air tank that injects air (or oxygen) into the mixed solution.
- A sump (commonly referred to as a “final clarifier” or “secondary reservoir”) separates biological sludge from clear, purified water by allowing biological flocs (sludge layers) to settle.
Treatment of nitrogenous substances or phosphates involves additional steps in the process to control the creation of anaerobic zones so that phosphates dissolve in a reducing environment and nitrogen oxides can be reduced to ammonium ions.
Purpose of Activated Sludge Process
In a wastewater (or industrial wastewater) treatment plant, the activated sludge process may be used for one or more of the following purposes.
- Oxidizing Carbon Material: Biological material.
- Oxidizing Nitrogen Substances: Mainly ammonium and nitrogen in biological substances.
- Phosphate removal.
- Distillation of trapped carbon dioxide, ammonia, nitrogen, etc. gases.
- Biological flocs are formed and easily precipitated.
- Obtaining a solution with a low content of dissolved or suspended solids