Like a Fine Wine, Water Needs To Breathe

Jim Lauria

During the holiday season, I enjoyed some great meals and fine wine. If there’s one thing I’ve learned about wine over the years, it’s that fine wine needs to breathe. Aeration opens the path for a wide range of chemical reactions: flavors develop, sulfites and sulfides waft away, and so does some of the ethanol that can lend a “hot” aroma to a newly opened bottle.

Aeration, or oxygenation, is just as vital to municipal wastewater and industrial effluent as it is to wine—maybe more so, because we don’t worry about the impact of wine on the environment downstream.

That’s probably not the image you want to contemplate as you swirl a glass of great Napa cabernet, but chemically speaking, it’s a big deal. Aeration helps increase dissolved oxygen (DO) and reduce biochemical oxygen demand (BOD) and chemical oxygen demand (COD), both of which can draw down DO and create eutrophic or hypoxic conditions—often called “dead zones” in places like the Gulf of Mexico, the Baltic Sea, or local lakes. Increasingly, the concentration of dissolved oxygen and the BOD/COD levels that could reduce DO are the subject of intense scrutiny.

Adequate levels of dissolved oxygen are vital to healthy water and a healthy ecosystem. Low levels can choke out fish, invertebrates, microorganisms and vegetation that are crucial to a balanced environment. Healthy water leads to a healthy environment and, ultimately, a healthy, sustainable business model—an operation that is resilient, efficient and backed by the trust of local stakeholders.

But needless to say, when you’re dealing with a couple million gallons at a time, aeration isn’t as easy as just swirling your glass.

There’s a lot of science behind designing systems that ensure effective gas transfer and proper mixing, especially in a limited amount of space. That’s where great designers, aided by computational fluid dynamics (CFD) modeling, come into play.

For a look at some of the most exciting solutions to those challenges, check out the November/December World Water, where I have an article on post-treatment aeration. Feel free to read it over a nice glass of wine.