What is Milorganite?

By Jaime Staufenbeil - Milorganite Agronomist
March 3, 2017

Milorganite microorganisms, microbes, bugs

Let’s start with what Milorganite® isn’t. It is NOT a bag of poop! (Seriously, it’s not.)

It’s a question we’ve heard countless times—for decades. There’s an obvious reason for the misunderstanding: Milorganite is the end result of Milwaukee’s sewerage treatment process. So, in the same sentence, you hear “sewerage” and “Milorganite.” People are bound to be confused.

So, if Milorganite isn’t poop in a bag, exactly what is it? It’s a bag of heat-dried microbes.  

There are several steps Milwaukee’s wastewater goes through to produce clean water and Milorganite fertilizer. 

Here are the Basic Steps to Recycle Wastewater into Milorganite® Fertilizer.

  1. Wastewater (including poop) flows into the water reclamation facilities.
  2. The first step in the water reclamation process is removing debris from the wastewater. Large and small objects like towels, wipes, plastics, sand, and gravel are removed.
  3. After the wastewater has undergone the initial screening process, it is pumped into the settling tanks, and fats, oils, and grease float to the top of the tank and are removed.
  4. The wastewater is pumped into aeration basin tanks. 
  5. Billions of naturally occurring microbes, which we call “bugs,” are introduced into the aeration tanks. With the help of introduced oxygen (air). The microbes ingest and break down the nutrients found in the organic material in the wastewater.  

6. After the bugs consume the nutrients in the organic material and there is nothing left to eat, they increase in size, clump together, and settle to the bottom of the tank. Water is squeezed out of the mass of microbes.

7. The microbes are heat-dried in a hot kiln reaching temperatures of 900–1,200° F.

8. It’s now pellets of heat-dried microbes. It’s Milorganite!

9. Milorganite is analyzed for at least 20 parameters every day to comply with all applicable safety guidelines.

10. The clean water is pumped back into Lake Michigan.

So, the next time someone says, “Milorganite is a bag of poop!” you’ll be able to set them straight. It’s a bag of microbes that ate well and were heat-dried.