What is the Aeration Process in Wastewater Treatment?
The aeration process, otherwise known as the biological process is considered to be the second stage of the Wastewater Treatment (WWT) process. Here, the filtered water from the sedimentation tanks enters the aeration lanes or activation tanks.
At this point, the wastewater still contains a large amount of very small organic particles and ammonia that are too small to be filtered out by the sedimentation tanks.
Large amounts of compressed air is introduced into the process via a submerged system of diffusers. The oxygen contained within the air is used to feed the naturally occurring microorganisms contained within the wastewater with bacteria, organic particles and ammonia effectively cleaning the waste from the water. This biological process takes as little as 5-6 hours.
Types of Aeration Processes
1. Bubble Aeration
Fine bubble diffusers are energy efficient submersible aeration systems used in wastewater treatment. This technology is a form of subsurface aeration that introduces air into water via thousands of very fine bubbles to promote the transfer of oxygen to water. This maximizes air-water contact in the process.
2. Coarse Bubble Aeration
Coarse bubble diffusers produce larger diameter bubble to displace, churn and mix the wastewater effectively. Coarse bubble aeration is best-suited for conventional aeration, highly loaded systems, sludge storage, aerobic digesters and channels.
3. Surface Aeration
Surface aeration is best when large amounts of oxygen are needed to be added to the water. More powerful diffusers are used to pump oxygen along the surface of mechanical objects.
Why is the Aeration Process Important?
The aeration or biological process plays an important role to remove bacteria and ammonia contained in the wastewater. This must be accomplished before the water can be returned to the environment
Ingersoll Rand Product Portfolio in the Aeration Process
Lobe, Screw, Multi-stage Centrifugal and Turbo Blowers
The blower technologies used in the aeration process can change depending on the design and operation of the wastewater facility. In general, the aeration process requires a large amount of air which is supplied by single or multiple blowers. Typically, the aeration process utilizes large Lobe & Screw Blowers, Multi-stage Centrifugal and High Speed Turbo Blowers.
Due to the constantly changing air demand (BOD - biological air demand) required by the aeration process, multiple blowers are utilized. They are controlled centrally to ensure efficient and continuous operation.
The air supplied by the blowers to the aeration basin has several functions. The first is to supply oxygen needed for metabolizing organic compounds in the wastewater. The oxygen must be dissolved in the wastewater in order to be used by the microorganisms. In this case, the diffusers use tiny bubbles of air to efficiently dissolve oxygen in the wastewater.
Secondly, additional oxygen is required when microorganisms convert ammonia (NH3) into nitrate (NO3), a process known as nitrification. Nitrification often represents half of the total process oxygen demand.
Mixers
Mixers are an essential part of the aeration (biological) process. Mixers can be surface mounted or submerged within the aeration lanes and are designed to ensure that the wastewater is constantly moving and that the air is distributed evenly. The use of mixers also eliminates dead-zones where the uneven distribution of oxygen can negatively affect the biological process.
Solutions by Brand
Visit Our Knowledge Center