The great weather on July 7th made for a nice stroll through the mostly pleasant-smelling Wastewater Treatment Plant in Two Harbors, which was holding an open house for the public to come and inspect how the city handles its well-used water. It may not be the most romantic topic, but the science of how toilet contents and other dirty water can be cleansed thoroughly enough to be deposited safely back into Lake Superior is beautiful in its own way: a process of many steps which systematically clears the water and removes the bad to, essentially, distill it back to its original state.
The wastewater treatment plant has undergone a lot of construction in the past decade to update the almost 70-year-old facility, resulting in a new chlorine contact tank, laboratory, office space, two clarifiers with domes, four aeration basins with supports, and much more. Much of the previous equipment was well past its life expectancy, with some pieces that were in operation for over 50 years.
In contrast, the facility as it stands today feels clean and modern. A guide map for the open house was provided near the entrance at the new garage, along with some snacks to take on your journey if you had the stomach for it. Knowledgeable workers were stationed throughout the plant at each noted section, happy to answer questions from curious guests. The self-guided tour ideally begins at the start of the dirty water’s path through the plant, pretreatment. Before anything else, large debris and other sizeable junk is separated from the water and disposed of. A sample of the condensed junk was on display nearby and looked to be formed mostly of cloth-like materials. “Even if it says on the packaging ‘flushable wipes’, they shouldn’t be flushed,” one of the workers commented, confirming that when it comes to your toilet, the only extra thing actually safe to send down the pipes is toilet paper. Anything else could run the risk of damaging the water system somewhere along the line.
After the removal of larger detritus, the water is sent to the aeration basins, enormous tanks which use oxygen and other natural processes to break down organic matter, removing pollutants. Two Harbor’s facility now has four, accessible via a tall set of stairs leading to walkways overlooking the basins. Next door, the operations building houses the majority of the technical equipment, control systems, and monitoring stations used to keep the plant running safely and efficiently.
On either side of the building are the two giant clarifiers, settling tanks where any remaining solids in the water are separated out. The center gently stirs the water, causing heavier material to sink to the bottom of the tank while the cleaner water flows outward and over the sides, moving on to the next stage of the process. The water passes through a series of filters that strip out fine particles, then is disinfected a final time, and now that it is properly clean, is deposited back into Lake Superior. The result keeps the Lake, animals, and humans healthy and the water ready to be used for whatever comes next.
One additional station covered biosolids thickening and hauling, which condenses sludge removed from the water during its treatment. These biosolids, which have been treated to meet EPA regulations for safe use, are then able to be transported and used elsewhere as fertilizer or similar. It shows some of the best modern technology has to offer; its clean and efficient operations help to keep not just Two Harbors but all of those along Lake Superior healthy and our settlements sustainable.
