University of Illinois, Urbana-Champaign
OP-28: Wastewater Management

All industrial and domestic wastewater generated on the main campus flows to the Urbana-Champaign Sanitary District for treatment before being discharged to a waterway. University facilities that discharge wastewater to the Urbana & Champaign Sanitary District are required to meet the District’s Ordinance 600 requirements. Please see this message from the Urbana-Champaign Sanitary District.
While our operations are in concrete tanks and appear industrial to the casual observer, what we do is still very much a natural operation that actually uses the same biological, chemical and physical processes seen in a wetland (please note, I didn’t say we mimic them, because we are using natural operations). We do use bacteria and microbes to break down pollutants, we use a minimum of mechanical equipment, chemicals and energy. So in my view what we do is entirely sustainable and natural. At the same time what we do is absolutely NOT a wetland and that’s because a wetland would not be sustainable, natural, nor effective in treating the volume of waste we see in an urban population in a northern climate (it would be an illegal discharger for much of the year).

The primary reason our current operations look industrial and have tanks is because we need reliable treatment that works year-round in a northern climate that has cold temperatures and precipitation. Lacking that reliability we would not be legal. A spread out wetland would fail to meet permit limits because the biology slows down too much as we approach freezing temperatures and biological systems shut down. So it is not a lack of interest in trying wetlands - it is we know they don’t do the job.

The only way to make a wetland legal this far north would be to store the sewage for months on end. Rather than build multi-billion gallon sewage storage ponds that hold a winter’s worth of sewage for the springtime, we simply make our natural system compact, so it doesn’t lose so much heat or slow down as much. (Muskegeon Michigan does store months of sewage - they spread the sewage on farmer’s fields in the summer. They are the only demonstration of this idea that I know of. USEPA funded it as a demonstration in the 1970s, but if that was common we are talking about having hundreds of acres of devoted to lagoons at every city, which is in its own way completely not natural)

In a similar vein, wetlands cannot produce the same reliable disinfection that is required for a legal discharge (that is certainly true in cold weather, I am not sure how they manage it in warm weather). So we use more chemicals and energy than zero, but it is the minimum that gets us to the performance we all demand.

Also, for those people who would argue a natural wetland would use zero energy, they need to take notice that the sewage needs to be pumped into the wetland. Pumping is either first or second largest energy demand in a modern/industrial treatment plant’s costs. It would be the same in a constructed wetland and the magnitude of the bill would be about the same too. So again, we’re just about as sustainable and natural as you get.

Finally, when a wetland is fed with the quantity of food/waste from 140,000 people it will produce tons of solids per day. That’s a basic truth. Removal of that much biota takes mechanical equipment and energy (or else it will wash downstream and just be pollution). We figured out a long time ago that if you have to remove tons of solids, having smooth concrete bottoms in tanks works a lot more efficiently (thereby using less energy), than a tank without a bottom. So although a wetland is a cool natural environment, it doesn’t work here, this far north, nor for cities as large as we live in today.

So in my view, we are at 100% naturally treated, 100% sustainable, but I expect that whoever wrote the question would probably feel we’re at 0% - obviously, I think they’re wrong.