On 8 September 2026, a ScienceBlog.com feature recapped a hundred-year-old recycling programme at the Milwaukee Metropolitan Sewerage District, where microbes that clean the city's wastewater are dried and pelletised into a lawn fertiliser sold under the name Milorganite, with a reported running total of more than 10.5 billion pounds diverted from landfill since the first railcar shipped on 10 February 1926 (ScienceBlog.com).
Key takeaways
- Production began in 1926 at the Jones Island facility, which the district describes as the world's first large-scale plant of its kind (ScienceBlog.com).
- Dead microbes are dried in high-temperature rotating kilns heated to 900-1,200 °F to kill pathogens and form pellets (ScienceBlog.com).
- The district now serves over 1 million customers in 29 communities, according to the same account (ScienceBlog.com).
- The National Association of Clean Water Agencies credited the district with having diverted over ten billion pounds of nutrient-rich pellets to residential, professional, and agricultural markets (ScienceBlog.com).
What happened
The 8 September 2026 feature describes Milorganite, a contraction of Milwaukee Organic Nitrogen, as a slow-release fertiliser made by the Milwaukee Metropolitan Sewerage District from the solids left over after the city's wastewater is biologically treated (ScienceBlog.com). Construction on the Jones Island plant started in 1923, and production began in 1926 with the first railcar shipping on 10 February that year, which the report calls one of the oldest recycling programmes in the country (ScienceBlog.com).
Peter Coffaro, the district's director of public engagement, is quoted describing the biological step: "They are eating the material. It's a short and happy life. They are eating a lot and they are reproducing" (ScienceBlog.com). Once the microbes run out of food, the cleaned water is disinfected and returned to Lake Michigan, and the dead biomass is dried in kilns heated to 900-1,200 °F to kill pathogens and form pellets that the maker says feed plants over about 8-10 weeks (ScienceBlog.com).
| Item | Reported figure |
|---|---|
| First commercial shipment | 10 February 1926 |
| Construction start, Jones Island | 1923 |
| Dryer temperature range | 900-1,200 °F |
| Customers served today | Over 1 million across 29 communities |
| Cumulative pellets diverted | Over 10.5 billion pounds (district history page); over 10 billion pounds (NACWA award citation) |
The same feature quotes Coffaro framing the procurement logic: "Most treatment plant processes, it's always about needing to remove that water and get that waste off and generally it goes to landfill, and we are able to recycle that product" (ScienceBlog.com). The report itself flags that the process details come mostly from the producer rather than an independent audit and should be read as the manufacturer's account of its own method (ScienceBlog.com).
Specification read
For a buyer translating the story into plant units: the source does not give a daily flow, BOD/COD load, or pellet output rate, so a project size in million litres per day or population equivalent cannot be derived from the article. A large US metropolitan secondary-clarifier train feeding a heat-drying loop of this size typically sits in the range of roughly 200,000-800,000 m³/day of mixed liquor feed (general industry range, not from the sources). The relevant treatment train for a biosolids-to-fertiliser line is screening → primary clarification → biological stage (conventional activated sludge, A2O, MBR, MBBR, SBR, or UASB depending on influent) → tertiary polishing and disinfection → sludge thickening and dewatering → thermal drying (direct or indirect kiln) → pelletising → bagging, and the event reported here is squarely at the thermal-drying and pelletising end of that chain, downstream of the biological reactor. If your plant looks like a large municipal activated-sludge works handling a few hundred thousand m³/day with several hundred mg/L BOD influent and you are facing rising landfill tipping fees or biosolids-destination compliance pressure, the Milwaukee case is the working example of turning the wasted activated sludge into a revenue product rather than a disposal line item. Readers running a similar train will want to weigh the capex and fuel bill of a 900-1,200 °F kiln against avoided disposal cost, and those scoping a packaged version of the same idea can start with our Municipal product hub or compare biological-stage options such as Mbr Membrane Systems when the upstream biology needs an upgrade before the dryer makes sense.
FAQ
What temperatures are the Milwaukee biosolids dried at, and why does that matter for pathogen control?
The reported dryer range is 900-1,200 °F in high-temperature rotating kilns, which the district describes as the step that kills pathogens and turns wet sludge into a dry, stable pellet (ScienceBlog.com). For procurement, that is the same envelope used for Class A heat-dried products in the US biosolids framework (general industry range, not from the sources).
How much biosolids has the programme actually diverted from landfill?
The district's own history page puts the running total at over 10.5 billion pounds, and a National Association of Clean Water Agencies award citation credits the district with over ten billion pounds of pellets delivered to residential, professional, and agricultural markets (ScienceBlog.com). The article does not break that down into a per-year or per-tonne rate.
Is the Jones Island process the same as a typical municipal activated-sludge plant with a dryer bolted on?
The report frames it that way: microbes treat the wastewater, the cleaned water goes back to Lake Michigan, and the dead biomass is dried and pelletised rather than landfilled, with Coffaro explicitly contrasting the district's approach with plants where the solids go to landfill (ScienceBlog.com). The source flags that these process details come mostly from the producer rather than an independent audit.
What lead time and supplier selection questions should a buyer ask if they want a similar line?
Lead times for a municipal-scale thermal dryer and pelletiser train typically run 12-24 months from order to commissioning once a site is permitted (general industry range, not from the sources). For supplier selection, buyers usually shortlist on fuel source (natural gas, biogas, or waste-heat), achieved pellet dryness, and prior reference plants of comparable size, and can compare biological-stage options such as Mbr Membrane Systems or the broader Municipal equipment range when scoping the upstream side of the train.
