High-Tech Tank To Dissipate Hippo Poo

Jul 7, 2016

Henry the hippo has said goodbye to the Dickerson Park Zoo in Springfield, Missouri and is now at the Cincinnati Zoo. Henry, 34, described as "one of the most charismatic animals at the zoo, is joined by a 17-year-old female named Bibi. A new exhibit will open July 21. In order to house them, the Cincinnati Zoo had to build an elaborate water filtration system, as described in this story which originally aired last summer.

Here's an encore presentation of the report:

The Cincinnati Zoo is in the midst of a massive project to make hippos feel welcome and give them a clean place to live.

The clean part sounds easier than it actually is because the dirty little secret about hippopotamuses is they poop a lot. Two of them defecate nearly 1,000 pounds a day. In essence Mark Fisher, vice president of the zoo's facilities, says he has to build a massive toilet that is nice and clean so visitors can view the hippos in an underwater tank.

Because this is such a difficult project, there aren’t very many underwater hippo displays. Fisher and others visited about a half dozen of them to see what worked and what didn’t. HGC Construction’s Greg Speidel was along for those visits.

He says, “The two main things that have to go right on this project is it has to be clean so people can see and it has to be an awesome exhibit that doesn’t leak!”

Just like The Greater Cincinnati Water Works cleans our water, filtering out impurities, the zoo’s system will do the same with screens, carbon and sand.

  • A rotating conveyer belt removes the larger items like fecal matter and straw (these get put into a dumpster system that the zoo will compost).
  • Sand filters remove smaller dirt.
  • Microfibers chemically balance the water.
  • The water is recycled.

Fisher calls this the most sustainable hippo exhibit in the world: “And why is that? Well, one of the cool factors is that even with a very fancy filtration system you’re always still going to lose a lot of water. Just (in) the filtration process itself you lose, it has to go to the combined sewer and it’s a large tank, 65,000 gallons. So where’s all the water coming from? It’s coming from our rain tank which we are literally standing on top of a 400-thousand gallon cistern that collects all the rain water from this side of the zoo. "

You might wonder why the Cincinnati Zoo is putting so much effort and money into the $7.3 million hippo exhibit. Fisher says it’s worth it. “Hippos are just fun and cool and bubbly and people just like to look at them."

The hippo exhibit is part of the Africa expansion. It is scheduled to open in July 21, 2016.

This story first aired July 20, 2015.