What is Wastewater Aeration?
Wastewater aeration is the process where air is circulated through, mixed with or dissolved in a liquid or substance. Aeration brings water and air into contact in order to remove dissolved gases, such as carbon dioxide and hydrogen sulfide, and to oxidize dissolved metals, including iron and volatile organic compounds (VOCs).
Wastewater aeration, in which air is mixed with wastewater to allow aerobic degradation of the pollutant components, is an integral part of most biological wastewater treatment systems.
This process is typically the first major process at drinking water treatment plants, and occurs in the secondary treatment processes of activated sludge treatment in wastewater treatment plants. An evenly distributed oxygen supply in a system is essential to effective wastewater treatment for fostering microbial growth.
Wastewater Aeration – When it is used
In municipal and industrial wastewater treatment, wastewater aeration is part of the secondary treatment process. The activated sludge process is the most common option in secondary treatment.
Wastewater Aeration in an activated sludge process is based on pumping air into a lagoon or lake, which promotes the microbial growth in the wastewater. The microbes feed on the organic material, forming flocks which can easily settle out. After settling bacteria forming the “activated sludge” flocks are continually recirculated back to the aeration basin to increase the rate of decomposition.
Why is Aeration important for Wastewater Treatment?
Wastewater aeration is one of the most critical components in a treatment system. A well-designed wastewater system that distributes oxygen evenly is a critical component of activated sludge treatment systems. An ample supply of oxygen is important for achieving rapid, economically viable and effective wastewater treatment.
Wastewater Aeration is important because it’s highly effective, economically viable, and great for the environment compared to other options.
Through proper maintenance and a proactive approach, waste facilities can reliably protect the environment and provide a practical solution for both small towns and large cities.
The benefits of Wastewater Aeration treatment:
The main benefit of the 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.
Wastewater Aeration Equipment
There are numerous kinds of wastewater and water aerators. The most common are surface aerators, which as the name implies, float on the surface of the lagoon, pond or basin they are aerating.
These could be:-
- fast or slow speed “splashers”,
- draft tube [propeller],
- or rotating brush [or paddle] types
There are also submersible lagoon aerators. These could be:-
- Submersible pumps with a draft tube
- Submersible pumps with a draft tube an ejector
What is common to both these kinds of systems, is that they cannot be easily accessed by operators for maintenance or repair. They need to be accessed by lifting devices [cranes etc], tether systems or by personnel rowing to them or using expensive infrastructure. This adds to overall maintenance costs, reduces the willingness to perform maintenance [increasing the potential for major breakdowns] and increases WHS risks.
An alternative to these systems is the EchoStorm venturi aerator from Gorman-Rupp. This system utilises a self-priming pump [mounted on the bank of the lagoon] to draw water from the lagoon. It then pumps that water at pressure through the EchoStorm unit. The EchoStorm water aerator uses an internal nozzle to accelerate the water to create a low-pressure area within the unit to draw in atmospheric air. It then mixes the air with the water and releases it [saturated with dissolved oxygen] back into the lagoon. Further advantages of this system include:-
- Dead-spot minimisation by being able to “aim” the discharge points to benefit mixing
- Quick, easy and safe maintenance
- Lower installation costs [only requiring a slab to mount the pump]
- Easy to scale by adding EchoStorm units to existing systems
