VaraCorp’s Cutting Edge Aerator
Wastewater engineers and project managers are always looking for the latest technology to inject dissolved oxygen into their wastewater lagoons. While engineers focus mostly on the oxygen transfer efficiency of an aerator, managers must focus on issues of maintenance and electrical costs. Sadly, great transfer efficiencies and low operating costs are often mutually exclusive.
Fortunately, a recent innovation in aeration technology solves the challenge of efficiency versus ongoing costs. The resulting aerator uses a subsurface rotating turbine as the vehicle for injecting dissolved oxygen. This turbine boasts high transfer efficiencies. Just as importantly, it requires little to no maintenance and requires unbelievably low electrical costs.
Before details of this new, cutting edge turbine aerator are discussed, it would help to have a quick overview of the technology employed by many existing aerators. Most popular aerators today fall into one of two categories. These categories are “splash” aerators and “bubble diffuser” aerators.
Splash aerators attempt to mimic rain as it falls to earth. Specifically, when rain travels through the atmosphere, it absorbs minute amounts of dissolved oxygen. In like manner splash aerators throw water into the air in an effort to saturate the water droplets with dissolved oxygen. Examples of splash aerators are paddle wheels (including brush wheels), fountain sprayers, and the water-pump aerators which use high-volume submerged water pumps to throw huge amounts of water straight into the air around the floating pontoons.
While some splash aerators can have relatively high transfer efficiencies, they all suffer from the same drawbacks. Notably, they tend to create large bubble sizes which escape too rapidly back into the atmosphere. Second, they often have gears and bearings which can require frequent maintenance and which reduce mechanical efficiency. Third, they require larger than normal motors just to overcome the inertia of water. Fourth, these relatively large motors consume a lot of electricity. Fifth, the contact time between the water droplets and the atmosphere is too short for the water to pick up much oxygen. And sixth, they tend to aerate only the top few feet of the lagoon.
Bubble diffusers come in two categories which are coarse bubble diffusers and fine bubble diffusers. These aerators normally consist of some sort of air compressor or air pump on the shore. This air pump forces air through a maze of pipes which typically are laid out in a pattern along the bottom of the lagoon. Air emitters are stationed at intervals along the submerged pipe, thus giving widespread coverage of dissolved oxygen. Some of the fine bubble diffusers are quite high in transfer efficiency. However, bubble diffusers can be haunted by serious drawbacks. The biggest challenge is the clogging of the emitters. Despite assurances from the makers of these aerators, these emitters can and most likely will clog, thus reducing coverage and efficiency. The only solution is to run some sort of acid through the pipes to clean the emitters or else pull out the maze of pipes and replace or clean out the emitters. Bubble diffusers are not practical in wastewater which tends to be high in contaminants and particulate matter.
In contrast to splash aerators the turbine aerator injects air into water which is more efficient and requires much smaller motors. Plus, the turbine is able to saturate water with dissolved oxygen at much greater depths than a typical splash aerator. Compared to bubble diffusers, the turbine has no emitters which can clog. And, unlike air diffusers the turbine can produce a mild sub-surface current which can disperse the dissolved oxygen in a lateral direction.
The bottom line is that the turbine is a relatively new, state-of-the-art aerator which overcomes many of the challenges which plague existing aerators.