00:00This facility removes more than 600,000 pounds of sludge from sewage and waste water every day.
00:08It's dumped into drying beds after a lengthy process here at the Stigny Water Reclamation
00:14Plant. Once dry, it'll be used as fertilizer in surrounding farms and fields. Stigny is located
00:23on the outskirts of Chicago, and at 413 acres, it's one of the largest wastewater treatment
00:30plants in the world. It processes all of the sewage from roughly 2.3 million nearby residents,
00:38and everything that arrives here will eventually be transformed into clean water,
00:42fertilizer, and energy to power the plant. When it rains, the facility can handle a whopping
00:491.4 billion gallons of wastewater in a single day. That's over 2,000 Olympic-sized swimming
00:57pools worth of wastewater. So when we're rocking and rolling, it's one million gallons getting
01:02treated each and every minute. Here, everything that flows down a drain has raw potential when
01:08it arrives. Well, after it goes through the first stop, the course screens. You could have
01:15snapping turtle water bottles. One time years ago, we had hundreds of feet of rope
01:21that just got trapped here, and it was this one large rope monster that we called it that had to
01:27be removed. So how does a facility like this tap into the potential of sewage, and what happens
01:35to everything that disappears down Chicago's drains? You flush the toilet or you take a shower,
01:41you never think of what happens to that water after it's gone down your drain. It's just out
01:46of sight, out of mind. That's Joe Cummings, the operations manager at Stickney, and he's been
01:52working here for over 15 years. I'm often asked what it's like working in a wastewater treatment
01:58plant. Now, I'm not going to sugarcoat it. You've walked past a manhole, a sewer, an outhouse,
02:04you know what those smells are. You are going to smell those things, because after all,
02:07it is raw sewage coming in. Once all that sewage arrives at the plant, there are two main processes
02:13at play. Treating the wastewater so it's safe to be released back into rivers, and transforming
02:20the solids into biosolids to be used as fertilizer. We're separating out the solid material that will
02:27settle to the bottom, a sludge, and the liquid that goes off back into the river system. The
02:32solids have been treated further to produce what we call biosolids cake, which is an earthy material.
02:38It's very good for being used as a fertilizer. What's happening at this plant recreates what
02:45happens organically in nature, condensing what would normally take several weeks into just a few
02:53hours. The process begins by sending sewage through a set of coarse screens. These screens
03:00have gaps to filter out larger objects, like garbage and plastics, and one item in particular
03:07that Joe and his team see often. This is as good a time as any to discuss flushable wipes. Just
03:13because you can flush them doesn't mean that you should. Those wipes do not break down in the sewer
03:19system. They don't break down inside the plant. So what happens is they come here, they find any
03:26jagged surface, and they just what we call rag up. They form into large blocks, and then ultimately
03:32we have to get those removed. So my advice, my request to everybody, don't flush flushable wipes.
03:41Once trapped, a rake scrapes up all the debris and transfers it to a conveyor belt. From here,
03:48it moves to a dumpster that will ultimately be transported to a landfill. Contrary to what most
03:55people might assume, Joe and the team here don't mind what the job entails. What everybody wants to
04:02know is, what does it smell like? As you can imagine, it smells like sewage. Right now we're at the first
04:09spot inside the plant where the sewage is actually exposed to air, and honestly it doesn't smell so bad.
04:17Once the wastewater passes through the coarse screens, it's pumped above ground to the aerated
04:23grit tanks. At this stage of treatment, the flow of water slows down. The lighter materials, like
04:30fats, oils, and grease, known as scum, float to the top of these preliminary tanks where the heavier
04:37solid waste, or sludge, settles to the bottom. Next, a series of rotating slats skims off the scum
04:45floating on the surface and scrapes up the sludge from the bottom of the tanks. That sludge goes on
04:51to our digesters, to our centrifuges, ultimately become our nutrient-rich fertilizer that we call
04:57biosolids. We'll come back to this sludge later. Meanwhile, the remaining wastewater passes through
05:05a primary settling phase before moving on to the secondary treatment tanks. Here, air is pumped into
05:13a tank of carefully maintained microorganisms that consume pollutants and other harmful substances
05:19in the water. This oxygen gives the bacteria what they need to perform an important job.
05:27Oxygen neutralizes the compounds such as ammonia, turns it into less toxic forms of nitrogen.
05:33Ammonia is toxic to the small fish and the larger fish that live in our waterways. So by turning it
05:40into nitrate and nitrite, it's a less toxic form that the wildlife can tolerate much better.
05:47These circular tanks, known as the final settling tanks, are the last stop in the process for
05:53treating wastewater at Stickney. Here, solids and liquids further separate. The remaining solids
06:01are removed and the treated wastewater is returned to the river. All of the liquid that you see
06:06traveling over that weir, that's going out to the sanitary and ship canal as treated effluent.
06:12This treated wastewater needs to meet specific quality standards set by the Illinois Environmental
06:20Protection Agency to ensure it does not harm the environment or pose a risk to the public.
06:26Samples are analyzed every day in its lab to ensure that treated wastewater is safe to be
06:33released. What we have here are some of the samples that we collect inside the plant.
06:38Just starting from the beginning, this is what raw sewage looks like. It's a mixture of 99.9%
06:45clean water and then all the solids that are in there. What we have here is mixed liquor. This is
06:52what is captured and treated in the aeration tanks and then settles out in the final tanks, the
06:58secondary treatment. So as you can see here, I shook this up a few minutes ago and you're already
07:03getting some of the separation of the solids separating out. The liquid that comes off the top
07:08of it, that's what goes back into the waterways and the solids are sent for further treatment.
07:14And then that water, after it comes out of there, is this. Looks very nice and clean. It's not
07:19drinkable. The important thing is we do not produce drinking water here, but it goes back out into the
07:24waterways much cleaner than it came. When the flushable wipes go into the system, they never
07:29break down. These have been in here for roughly four years. While the wastewater is being treated
07:36and released, the sludge is moving on to a different area to be treated through centrifugation
07:42and digestion. Inside these centrifuges, the sludge is mixed with a polymer and spun at high speeds.
07:51This helps further separate the solids from the liquids. The digesters break down the organic
07:57matter in the sludge through a process called anaerobic digestion. Here, solids are heated
08:04and broken down by microorganisms to produce a biogas product. Think of it as your stomach
08:11just digesting, breaking down the solids, and as part of that process, it actually produces methane
08:17gas that is reused in the plant for part of our energy uses. After this, it enters a set of
08:23centrifuges again, resulting in a biosolids cake. On an average day, this facility will produce over
08:321,000 wet tons of biosolids cake. These are loaded into railcars to be handled at a separate facility.
08:40This is where all of the biosolids that have been produced from our centrifuges that you saw
08:44upstairs, that go onto the conveyor belt system, all go into our hoppers and then are deposited
08:50into our railcars. We fill up roughly one railcar with 70 wet tons of biosolids in one shift.
08:58Over the course of a normal day, we might fill up enough railcars for 1,000 to 2,000 wet tons of
09:05biosolids. The railcars transport this material a few miles away on a private railroad and the
09:13biosolids are dumped into a lagoon for additional treatment and drying. The final product is
09:21fertilizer that can be used on farm fields, golf courses, parks, and recreational facilities.
09:28One thing that's special about the Stickney plant is because of the size of it, we do a lot of things
09:32in-house. We have an entire laboratory right here that we do the monitoring and the research. One of
09:38the research things that we have that might surprise people is we have a greenhouse. We will
09:43take our biosolids, that nutrient-rich fertilizer product, and we'll mix it with soils, blend it in
09:50different proportions, test it on many different species, and that's all to determine what is the
09:56optimum use for that biosolid. When used as fertilizers, biosolids can have several positive
10:02impacts. They've been shown to improve soil health, reduce nutrient loss, and increase the amount of
10:09water soil can retain. The main thing that the Stickney Water Reclamation Plant and all of our
10:15plants are doing is to protect the water environment. Toilets are not trash cans. Just because
10:20something can be flushed down the toilet does not mean that it should be. So what you should really
10:25concentrate on is your bodily waste, your toilet paper, that's what should go down the toilet.
10:31Street drains, you should keep those clear because anything, when the rain falls, it's going to sweep
10:36everything into the street drain and it's all going to come here. In general, Stickney is considered
10:41the biggest or one of the biggest plants in the world. In the state of Illinois, the average plant
10:46is probably treating about 1 million gallons a day and we're treating 1,440 times that during high flow.
Comments