Aeration is an activated sludge process, promoting microbial growth in the wastewater. The microbes then feed on organic material, forming flocks which easily settle out. Once settled in a separate settling tank, bacteria forming the “activated sludge” flocks are continually recirculated back to the aeration basin, increasing decomposition rates.

How does Aeration Work?

Aeration provides oxygen to bacteria for treating and stabilizing wastewater. Oxygen is needed by the bacteria to allow biodegradation to occur. The supplied oxygen is utilized by bacteria in the wastewater to break down the organic matter containing carbon to form carbon dioxide and water. Without the presence of sufficient oxygen, bacteria are not able to biodegrade the incoming organic matter in a reasonable time. In the absence of dissolved oxygen, degradation must occur under septic conditions that are slow, odorous, and yield incomplete conversions of pollutants. Under septic conditions, some of the biological processes convert hydrogen and sulfur to form hydrogen sulfide and transform carbon into methane. Other carbon will be converted to organic acids that create low pH conditions in the basin and make the water more difficult to treat and promote odor formation. Biodegradation of organic matter in the absence of oxygen is a very slow biological process.

Why is Aeration Important for Wastewater Treatment?

Aeration is the most critical component of a treatment system using the activated sludge process. A well-designed aeration system has a direct impact on the level of wastewater treatment it achieves. An ample and evenly distributed oxygen supply in an aeration system is the key to rapid, economically-viable, and effective wastewater treatment.

Types of Aeration

Fine Bubble Diffusers

Fine bubble diffusers are energy efficient submersible aeration systems for wastewater treatment. Fine Bubble diffuser systems disperse the diffused gas volume to transfer an equal amount of oxygen as a coarse bubble system, according to Environmental Dynamics International.

Coarse Bubble Diffuser

Coarse bubble diffusers eliminate clogging in wastewater systems while maximizing airflow and mixing capabilities. Operators often use these as alternative methods to fine bubble diffusers, which are efficient but more susceptible to plugging risks. With ReliaBall coarse bubble diffusers for sale from SSI Aeration, users will be more equipped to handle challenging industrial applications that require durable treatment solutions.

Aeration Methods in Activated Sludge Process

 

1.    Diffused Air Aeration

In diffused air aeration method compressed air is blown through the sewage and air is diffused in sewage by a diffuser.

2.    Mechanical Aeration

In this method, the surface of sewage is agitated violently with the help of some mechanical equipment to encourage the absorption of oxygen from the atmosphere. There are two well-known forms of the mechanical aerator.  Vertical surface aerator and Horizontal surface aerator

3.    Combine Aerator

In this system, diffused air aeration and mechanical aeration are combined in a single unit. The well-known type of such combination is the Dorroco aerator. The aeration of sewage is done by air diffusers as well as mechanical aerators. Air diffuser plates are located at the bottom of the tank and the submerged paddles rotate in the direction opposite to that in which the compressed air rises up from the air diffusers. Paddles are rotated by a motor on a horizontal shaft with a speed of 10-12 rpm.

The benefits of Wastewater Aeration treatment:

The main benefit of aeration is that it uses natural microorganisms from the water to remove pollutants. The chemicals used in other treatment systems can be harmful when used in high volumes, but the aeration process uses microorganisms naturally found in wastewater.