The Stickney Water Reclamation Plant in Illinois is one of the largest wastewater-treatment facilities in the world, serving about 2.3 million people and cleaning an average of 700 million gallons of wastewater a day. During rainfall, the facility can handle a whopping 1.44 billion gallons of wastewater in a single day — that's a million gallons every minute.
The clean water is released into the Chicago Sanitary and Ship Canal, and the sludge that is removed from the water is converted to biosolids, which are a sustainable alternative to chemical fertilizers.
For more, visit: https://mwrd.org/what-we-do
The clean water is released into the Chicago Sanitary and Ship Canal, and the sludge that is removed from the water is converted to biosolids, which are a sustainable alternative to chemical fertilizers.
For more, visit: https://mwrd.org/what-we-do
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TechTranscript
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.