Here in Northern Colorado, we place a high value on certain things: clean waterways, mindful energy use and good beer, to name a few. With recent process improvements at the South Fort Collins Sanitation District (SFCSD), those first two things just received a big boost—and because the science of wastewater treatment can be a challenge to relay, we’ll use good beer to help explain why.
You may recall hearing about our ongoing plant expansion, which has allowed us to do some cool new things like Autothermal Thermophilic Aerobic Digestion (no, that’s not a fancy celebrity diet). Well, there’s another addition we’re pretty proud of, and that’s the inclusion of a step-feed process into our wastewater treatment. The name is simpler than autothermal thermophilic aerobic digestion, but the process is still complex. That’s where the beer comes in handy.
What is a step-feed?
Think of it as incremental, like the name suggests.
When we intake wastewater (let’s call that dirty water influent) at our facility, it’s difficult to process it efficiently en masse. The SFCSD serves 50,000 residents in Northern Colorado, so there’s a lot of influent to process every day. In order to promote efficiency in our process—and do some other cool things that we’ll get to in a minute—we’ve introduced a step-feed at the beginning of the treatment process.
What does this have to do with beer? Not a whole lot but it helps paint a picture.
Think of those hoppy beers you find around Fort Collins—fragrant, a little bitter, very delicious. When brewers add hops to their beer, they’ll often do it at various stages throughout the brewing process. Sometimes, this involves syphoning in-process beer through a hop tank for maximum exposure to the hops, and then back to the fermenting or conditioning tank. Doing this in increments allows for maximum exposure while also promoting beneficial chemical reactions.
Our step-feed process is, well, kind of similar in design—similar in the sense that we syphon off portions of influent, expose it to controlled environments that break down organic compounds, and then return it to the pipeline as it moves along the treatment stages. Our step-feed has four distinct treatment zones, two are anoxic and two are aerobic.
Here’s how it looks in action:
- A portion of influent enters the first anoxic zone (oxygen deficient) and then passes into the first aerobic zone (oxygen rich).
- A portion of the first aerobic zone then gets returned into the first anoxic zone to help with de-nitrification. Aerobic zones turn ammonia into nitrates. Anoxic zones work on those nitrates.
- The first aerobic zone, along with a portion of the influent, then enters the second anoxic zone.
- This continues into the second aerobic zone with a portion of it returning to the second anoxic zone.
- All of this eventually flows into the clarifiers, then into filtration and disinfection, and finally to Fossil Creek Reservoir.
All of this to say that each step helps efficiently break down and filter out specific compounds. So, it’s not really similar to hopping an IPA, but you get the idea.
Why install a step-feed?
This addition to the facility gives us the ability to treat wastewater in new ways, and with less financial and energy costs. Primarily, because of the multiple anoxic and aerobic zones, the step-process can more easily treat or remove organic compounds and ammonia. It also expands the facility’s overall treatment capacity of biological oxygen demand (BOD).
This is extremely important because compounds like nitrogen are detrimental to our waterways when concentrated. In fact, high concentrations of nitrogen are responsible for algae blooms, which stifle aquatic life and can harm fragile ecosystems. By breaking those compounds down and converting them, we’re able to return clean water back to the source without negatively impacting our natural systems.
As an added bonus, this step-feed process allows the SFCSD to do all of these new, environmentally-friendly actions while also improving our economic efficiency.
What’s next for the SFCSD?
The Fort Collins-Loveland Water and the South Fort Collins Sanitation Districts have provided water and wastewater services to businesses and citizens since 1961. The District serves an area that encompasses approximately 60 square miles with boundaries that range from south of Harmony Rd. to 57th Street in Loveland, then east from the foothills to the Larimer-Weld County line. We mention this because, with our long history serving such a rapidly changing and growing region, we’re always looking at next steps.
The best way to stay up-to-date with the goings-on of the FCLWD and the SFCSD is to keep an eye on our blog. We’re always geeking out on the full water and wastewater treatment process. Recent posts include: How to take a 24-7 wastewater treatment plant offline, Preparing for the runoff from last summer’s wildfire, and a special spotlight on longtime FCLWD board member Jim Borland. Follow us on Facebook and those blogs will come right to you every month, or sign-up for emails and you’ll get those updates (and more!) in your inbox once a quarter.