In a bubble aeration system, air is injected at the bottom of a tank to create bubbles. As the bubbles rise, THMs diffuse from the water into the bubble, until the bubble becomes saturated with THMs. Eventually, the bubble reaches the surface and pops – delivering THMs into headspace.
In a surface aeration system, a motorized device churns the water and air together, allowing THMs to transfer from water into the air.
Spray aeration is the process of pumping water from the floor of the tank to the ceiling, and spraying it down through a set of spray nozzles. As each droplet flies out of spray nozzle, THMs evaporate out of the droplet and into the air.
Over the lifecycle of an in-tank aeration system, energy costs dominate. Different aeration technologies can vary in their effectiveness and energy usage, so it is important to look at the energy consumption versus MGD of water treated.