What is Milorganite?

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Quick Tips

  • Milorganite is composed of heat-dried microbes
  • The microbes are expended, harvested, dried and turned into organic fertilizer
  • Milorganite is regulated by the EPA and complies with the most stringent requirements

What is it?

Milorganite fertilizer is one of the oldest branded fertilizers on the market today.  It is derived from heat-dried microbes that have digested the organic material in wastewater.  Milorganite is manufactured by the Milwaukee Metropolitan Sewerage District.  The District captures wastewater from the metropolitan Milwaukee area, including local industries such as MillersCoors.  This water is then treated with microbes to digest nutrients that are found in it.  Cleaned water is then returned to Lake Michigan.  The resulting microbes are then dried, becoming Milorganite fertilizers.  The Milorganite program is one of the world’s largest recycling efforts.

How Do We Make It?

Wastewater enters the Jones Island water reclamation facility, where all solid materials such as sand, boards, shop rags, etc. are removed.  Microbes are added to the leftover water during the activation process, which serves the same purpose as adding yeast to bread.  Oxygen is pumped in to create an ideal environment and the microbes digest the nutrients in the water.

When all the nutrients have been consumed, the microbes die.  Agents are then added to begin clumping the microbes together.  This process of settling and coagulating takes place in quiet sedimentation tanks. 

After settling, the clumped microbes are removed and sent to the Dewatering and Drying building where moisture is removed using belt presses.  This produces a semi-solid form similar to wet cardboard that is subsequently dried in twelve rotary driers at temperatures ranging from 900⁰ - 1200⁰F.  Any surviving pathogens are killed from the extreme hot temperatures.  

The product is sampled thoroughly in our testing process, including over 20 tests per day, which guarantees Milorganite complies with standards for protecting human health and the environment.  It is then ready to be packaged for homeowners, landscapers and golf course superintendents throughout North America.