How Chicago Cleans 1.4 Billion Gallons Of Wastewater Every Day | Deep Cleaned | Insider

Narrator: This facility removes more than 600,000 pounds of sewage sludge each day. It is poured into drying beds after a long process here at the Stickney Water Reclamation Plant. Once dry, it will be used as fertilizer on surrounding farms and fields. Stickney is located outside Chicago and, at 413 acres, is one of the largest

wastewater

treatment plants in the world. It processes all

wastewater

from approximately 2.3 million nearby residents. And

every

thing that gets here will eventually be transformed into clean water, fertilizer and energy to feed the plant. When it rains, the facility can handle a whopping 1.4

billion

gallons

of wastewater in a single day.

This is equivalent to more than 2,000 wastewater from Olympic swimming pools. So when we're on the move, 1 million

gallons

are treated

every

minute. Narrator: Here, everything that flows down a drain has raw potential when it arrives. Well, then it goes through the first stop: the coarse sieves. Narrator: So how does a facility like this harness the potential of wastewater? And what happens to everything that disappears down Chicago's drains? You flush the toilet or take a shower, you never think about what happens to that water after it goes down the drain. It's just out of sight, out of mind.

Narrator: That's Joe Cummings, Stickney's operations manager, and he's worked here for over 15 years. Joe: I am often asked what it is like to work at a wastewater treatment plant. Now, I'm not going to sugarcoat it. You have passed through a sewer, a sewer, a toilet. You know what those smells are. You're going to smell that stuff, because after all, it's raw sewage. Narrator: Once all that wastewater reaches the plant, there are two main processes at play: Treating the wastewater so that it is safe to be returned to the rivers. and transform the solids into biosolids to be used as fertilizer.

Joe: We are separating the solid material that will settle to the bottom, a sludge, and the liquid that returns to the river system. The solids have been further treated to produce what we call biosolids cake, which is an earthy material. It is very good to use as fertilizer. Narrator: What happens in this plant recreates what happens organically in nature, condensing what would normally take several weeks into just a few hours. The process begins by sending the wastewater through a set of coarse screens. These screens have spaces to filter out larger objects, such as trash and plastics, and one particular item that Joe and his team see frequently.

Joe: This is as good a time as any to talk about disposable wipes. Just because you can throw them away doesn't mean you should. Those wipes don't spoil in the sewage system. They do not decompose within the plant. So what happens is they come here, they find any uneven surface and they just do what we call mopping. They form in large blocks and ultimately we have to remove them. So my advice and my request to everyone is not to flush the wipes down the toilet. Narrator: Once trapped, a rake scrapes all the debris and transfers it to a conveyor belt.

From here it goes to a garbage container that will finally be transported to a landfill. Contrary to what most people might assume, Joe and the team here don't care what the job entails. Narrator: Once the wastewater passes through the coarse screens, it is pumped to the surface into aerated sand tanks. At this stage of the treatment, the flow of water slows down. Lighter materials such as fats, oils and greases, known as scum, float to the top of these preliminary tanks, while heavier solid waste, or sludge, settles to the bottom. Next, a series of rotating slats remove foam floating on the surface and scrape sludge from the bottom of the tanks.

Joe: That sludge goes to our digesters, to our centrifuges. Ultimately, they become our nutrient-rich fertilizer we call biosolids. Narrator: We'll come back to this mud later. Meanwhile, the rest of the wastewater goes through a primary settling phase before moving to secondary treatment tanks. Here, air is pumped into a tank of carefully maintained microorganisms that consume contaminants and other harmful substances in the water. This oxygen gives bacteria what they need to do important work. Joe: Oxygen neutralizes compounds like ammonia and converts it into less toxic forms of nitrogen. Ammonia is toxic to small and large fish that live in our waterways.

So by converting it to nitrate and nitrite, it is a less toxic form that wildlife can tolerate much better. Narrator: These circular tanks, known as final settling tanks, are the last stop in the wastewater treatment process at Stickney. Here, solids and liquids are further separated. The remaining solids are removed and the treated wastewater is returned to the river. All the liquid that is seen traveling through that dam goes out to the sanitary and navigation canal as treated effluent. Narrator: This treated wastewater must meet specific quality standards established by the Illinois Environmental Protection Agency to ensure that it does not harm the environment or pose a risk to the public.

Samples are analyzed every day in their laboratory to ensure that the treated wastewater is safe to be released. What we have here are some of the samples we collected inside the plant. Starting from the beginning, this is what raw sewage looks like. You know, it's a mixture of 99.9% clean water and then all the solids that are in there. What we have here is mixed liquor. This is what is captured and treated in the aeration tanks and then settles in the final tanks, the secondary treatment. So as you can see here, I shook this a few minutes ago and you're already getting some of the separation of the solids.

The liquid that comes out of the top is what goes back into the waterways, and the solids are sent for further treatment, and then that water, after it comes out of there, is this. It looks very nice and clean. It is not drinkable. The important thing is that we do not produce drinking water here, but it returns to the water courses much cleaner than it came from. When disposable wipes enter the system, they never go bad. These have been here for about four years. Narrator: While the wastewater is treated and released, the sludge passes to another area to be treated through centrifugation and digestion.

Inside these centrifuges, sludge is mixed with a polymer and spun at high speeds. This helps to further separate solids from liquids. Digesters break down organic matter in sludge through a process called anaerobic digestion. Here, the solids are heated and decomposed by microorganisms to produce a biogas product. Think of it as your stomach digesting and breaking down solids. And as part of that process, it actually produces methane gas that is reused in the plant for some of our energy uses. Narrator: After this, it again enters a set of centrifuges, resulting in a cake of biosolids. On a typical day, this facility will produce more than 1,000 wet tons of biosolids cake.

These are loaded onto railcars to be handled at a separate facility. Joe: This is where all of the biosolids that were produced from our centrifuges that you saw above that go to the conveyor system go into our hoppers and then are deposited into our rail cars. In one shift we fill approximately one car with 70 wet tons of biosolids. Over the course of a typical day, we could fill enough railcars to transport 1,000 to 2,000 wet tons of biosolids. Narrator: Railcars transport this material a few miles away on a private railroad, and the biosolids are dumped into a lagoon for further treatment and drying.

The final product is a fertilizer that can be used on agricultural fields, golf courses, parks and recreational facilities. One thing that's special about Stickney Plant is that, because of its size, we do a lot of things in-house. We have a full lab right here where we do monitoring and research. One of the research things that we have that might surprise people is that we have a greenhouse. We're going to take our biosolids, that nutrient-rich fertilizer product, and we're going to mix it with soil, we're going to combine it in different ratios, we're going to test it on a lot of different species, and that's it to determine what the optimal use is for that biosolid.

Narrator: When used as fertilizers, biosolids can have several positive impacts. They have been shown to improve soil health, reduce nutrient loss, and increase the amount of water the soil can retain. Joe: The main thing that the Stickney Water Reclamation Plant and all of our plants are doing is protecting the aquatic environment. Bathrooms are not trash cans. Just because something can be flushed down the toilet doesn't mean it should be flushed. So what you should really focus on is your bodily waste, your toilet paper. That's what should go down the toilet. The street drains, you have to keep them clear, because anything, when the rain falls, is going to sweep everything into the street drain and everything is going to come here.

Stickney is generally considered the largest or one of the largest plants in the world. In the state of Illinois, the average plant probably treats about 1 million gallons per day, and we treat 1,440 times that during high flow.