If left to its own devices, wastewater takes a very long time to naturally biodegrade. And, as it sits, it creates an intense odor and potent chemical reactions. Luckily, there is a way to speed along the process so the organic matter can biodegrade and the smell can diminish. As such, the water needs to be treated. Some treatment plants opt for chemical treatments to stabilize the contaminants; however, by injecting the wastewater with oxygen (a.k.a. aeration), the same benefits can be achieved.
Why is aeration necessary?
Bacteria are an important part of wastewater—they break down the organic matter found in wastewater and convert it to carbon dioxide and water. While the bacteria can get the job done on their own, it takes an incredibly long time, and is not nearly as effective. In fact, instead of being converted to carbon dioxide and water, the wastewater can create hydrogen sulfide, which then transforms carbon into methane. Some of the carbon will be become organic acids, which will make the water harder to treat and lead to odor formation.
How does aeration work?
The process of breaking down wastewater can be streamlined by feeding the bacteria what they need to thrive: oxygen. When oxygen is injected, the bacteria are able to regenerate quickly and break down the wastewater more efficiently. There is no chance for the wastewater to create hydrogen sulfide or methane gas. Plus, the oxygen levels can be adjusted based on weather conditions so that the bacteria are always getting enough to increase their survival and regeneration rates.
When does aeration occur?
The treatment of wastewater is a multistep process. In industrial and municipal wastewater treatment plants, oxygen is injected during the secondary treatment process. Also known as the activated sludge process, the oxygen is pumped into the wastewater tank to encourage the growth of the bacteria. As the bacteria consume the organic matter, they form flocs, which quickly settle out and become separated in a different tank. This cycle is repeated continuously to make sure the decomposition process is as quick as possible.
Aeration system design
It is not enough to simply inject the wastewater with oxygen; it needs to be distributed with precision to be effective. Both the amount of oxygen used and the way it is injected make a difference. There needs to be enough oxygen to feed all of the bacteria, and it must be distributed evenly so that all of the bacteria get their share.
An on-site PSA oxygen generator from On Site Gas Systems ensures there is always enough oxygen to keep up with the demand, without the inconvenience or ongoing expense of cryogenically produced oxygen.
Debbie Pereira is the chief financial officer at On Site Gas Systems, LLC.