funding for this program is brought to you by the arts and cultural heritage fund and the citizens of minnesota [Music] the western lake superior sanitary district or wlssd human and industrial waste were main factors in contamination of the estuary since the 1970s this wastewater treatment plant has treated all municipal and industrial sewage in the duluth cloquet area while most of the sewage is natural it's certainly not desirable let's check it out so we think the first kind of help to the river was a really a change in bringing trees back and having watersheds start to function in that more historical kind of way where the trees were soaking up water and keeping soils on the landscape the next big step was us figuring out how to treat city waste sewer waste and industrial waste and in the for the st louis river the big help was setting up the western lake superior sanitary district in the 1970s not only did it treat our sewage it also treated some of the pulp mill waste and paper waste coming from the regional facilities that was a big step forward and immediate improvements were observed in the quality of the river so we have 17 communities that our customers along with four industrial customers those folks are sending us wastewater every day we take a look at it and we monitor the flow so how much water are they sending us and we also look at how dirty it is so to do that we measure bod which is biological oxygen demand and the total suspended solids so it's how chunky it is and then we measure how hard our bugs have to work to clean it up just like you and i the bugs use oxygen when they're trying to gobble stuff up and working hard so we measure how much oxygen they're using as they're cleaning up our wastewater how is wlssd different from other water treatment plants they're actually a really unique plant in the state of minnesota there aren't a lot of plants that are that big that are both handling municipal waste or household waste and industrial waste and the the waste that comes from the paper mill is pretty strong they have to try really hard to get the waste out of there but they do a good job of it [Music] our effluent or the cleaned up wastewater is actually cleaner than what's already out in the st louis river so we have a living process we have lots of microbes and bugs and bacteria that are working hard to clean up our wastewater we're standing on top of the reactor deck this is actually where the bulk of wastewater treatment happens underneath our feet we have what we like to call a concrete river so the water snakes back and forth through these concrete channels and along the way it's encouraged by these motors you'll see several of them along the top of the reactor deck they're operating big paddles that are churning up that water it's full of waste which we can also call food the other thing that's being constantly bubbled in is pure oxygen this is a unique characteristic of our wastewater treatment plant many wastewater treatment systems use regular air we actually have a oxygen plant where we create pure oxygen to help feed all those bugs and bacteria that are working to eat the waste out of the water and you can imagine when they have all that oxygen all the food they could eat and that they're nice and warm what do they do they grow and divide the bacteria that are here working for us at the wastewater treatment plant we don't add them they're actually donated by people like you they're in the pipes they're in the sewer system already and it makes sense because they're already there obviously they like to eat the stuff that's in there once all those bacteria have grown and divided inside the reactor deck we don't just get rid of them they're working hard for us and we want them to keep working so we actually send most of them right back into the wastewater treatment process and they're being mixed up by these paddles as well right along with that pure oxygen this is the water that's in the reactor deck and it's almost cleaned up and ready to go back out into the river we mentioned that bacteria are the real workers at wlssd and they're cleaning up all the waste water for us because they have that pure oxygen they have all of that food and we're mixing and churning that water up for them those bacteria grow and divide and they make the water look much darker and murkier than it did when it first came here our wastewater has just left the reactor deck and the water portion is pretty much cleaned up and ready to go back out in the river however it's still mixed in with our solids now the solids aren't what you're thinking at this point it's actually all the waste has been cleaned up but we have a lot of bacteria and dead bacteria bodies so the wastewater heads into our clarifiers the cleaned up wastewater is drawn off the top and the solids settle down to the bottom the cleaned up wastewater has a couple more polishing steps and then it heads back out into the river [Music] programming is supported by western lake superior's sanitary district innovating solutions and reducing mercury pollution in the st louis river through research and community programs online at wlssd.com