An aeration tank is a place where a liquid is held in order to increase the amount of air within it. The most common uses of aeration tanks are in wastewater recovery, as the high oxygen levels will increase the speed at which the water is cleaned. There are two main methods of aerating liquid: forcing air through the liquid or forcing liquid through the air. Both methods are common, but the aeration tanks are very different between the two types.
Wastewater reclamation using an aeration tank is very common. The water is mixed with biological agents and then aerated. The increased oxygen promotes the growth of the beneficial biological material. That material will consume unwanted waste products held in the water. Finally, the beneficial material will grow due to the increased oxygen and food, which makes it easier to filter from the clean water.
There are two main types of aeration tanks. When a tank has air forced through it, it is generally very shallow and wide. Tanks that put the water into the air are usually tall and take up significantly less ground space than the other tanks. In both cases, the tanks are typically open to the air, promoting additional natural aeration.
In an air-through-water aeration tank, the tanks have the aeration system built on the bottom. This usually consists of nozzles that force air through the wastewater. In many ways, this system works like the aeration system in a household fish tank, just on a larger scale. The nozzles cover the bottom of the tank, forcing air up continuously. In addition, these tanks usually have a system that moves the water around, making the mix more complete.
These tanks have an additional feature that isn’t present on other aeration tank styles. Since the gases are pumped into the water through the system, the operators can change the gas mixture however they want. This allows them to add additional oxygen for particularly dirty water or other gasses for other purposes.
A water-through-air aeration tank is a little more complicated. These tanks have a column-like pipe that comes up through the center of the tank. At the top of the column is a cone-shaped sprayer. The water from the tank is pumped up the column, where it hits the sprayer. The cone breaks the liquid into fine streams and mist. As this water recollects against the sides of the tank and in the air, it absorbs a lot of additional air before falling back into the tank.