Water aeration is the process by which oxygen is added or injected into water to help purify it. Although everyone has been taught in basic science that water consists partly of oxygen, the fact is that water can become anoxic, to use the correct scientific term. When this condition occurs, fish and other oxygen dependent creatures cannot survive, and algal blooms spread unchecked in pools and fountain reservoirs, lakes and streams. Another consequence is the buildup of dead organic matter which cannot be properly decomposed without sufficient oxygen content in the water.
Everyone should know what an aerator is. After all, it’s what caps your home faucets in the kitchen and bathrooms. Just the action of the water passing through it draws in oxygen to help purify the stream. Maintaining fresh water in reservoirs requires industrial scale large aerators. Water aeration is accomplished by one of two methods. Surface aeration operates on the principle of direct contact between the water and the atmosphere to draw in oxygen Subsurface aeration draws oxygen through a compressor at one end, ducts it through piping or hoses with the outlet placed deep under the surface, and bubbles the oxygen into the water at that point. Basically, that’s the mechanism for a fish tank’s oxygenator, but an industrial subsurface aerator operates on a far larger scale.
The simplest form of surface aerator is a fountain. Water is driven up by a mechanical impeller and released as a jet. As the water column breaks up, the droplets take in oxygen from the air and fall right back into the reservoir. Floating surface aerators essentially disrupt the water to bring it into direct contact with the air. Paddlewheel aerators are mounted on pontoon floats and churn the water to bring it into direct air contact.
Large-scale water aeration is also used for lake destratification. Extreme thermal gradients reduce oxygen levels to the point of killing off the fish and allowing the buildup of plankton. These units essentially inject fresh oxygen and adjust the thermal balances of the lake to restore the proper environment. Other applications for industrial aerator units include the water purification systems used in sewage treatment plants, the pumps and jets for public fountains, the paddlewheels used for water purification in aquaculture processes, and large oxygenation barges which are utilized to offset the large-scale injection of deoxygenated water from sewer runoff during heavy storm activity.