Sludge Management Cost Reduction

Innovative sludge management option provides significant cost savings for dairy processor's wastewater treatment


In 2011-2012, multiple dairy processors in Southwestern Wisconsin joined forces and turned to The Probst Group to design and build a centralized wastewater treatment plant. The state-of-the-art facility integrates multiple treatment methods to ensure compliance with their permitted discharge limits, including the ultra-low phosphorus limit of 0.075 mg/L. Removing phosphorus and other nutrients from the wastewater results in nutrient-rich sludge that must be appropriately managed. Agreements with the City required that no liquid waste be hauled from the facility, and landspreading caked sludge is subject to weather conditions. Treating an average of 1.2 million gallons per day (MGD) of wastewater meant there were significant costs associated with storing and hauling the sludge for disposal. Focused on providing wastewater solutions based around the clients’ unique needs, the Probst team was determined to provide a new outlook on sludge management that would provide additional cost savings. Probst provided an innovative solution that provides significant cost savings, as well as allows vital nutrients to be returned to the land when and where they are needed.


  • Reduce sludge disposal costs
  • Utilize nutrient value in the solids generated from the treatment process
  • Maintain regulatory compliance and agreements with the City


Utilizing the collective expertise of the Probst Operations, Engineering, and Compliance teams, multiple options for cost reduction associated with sludge handling were explored and presented to facility owners.  

Working closely with the Wisconsin Department of Natural Resources and the client, Probst was able to provide a unique solution; Classifying the solids generated from the treatment process as a fetilizer under the Wisconsin Department of Agriculture, Trade, and Consumer Protection.

Probst managed all facets of pursuing and obtaining the fertilizer designation including:

  • Managing permitting and licensing process with DATCP
  • Developed relationships with local farmers and local haulers to identify and secure partners interested in receiving the fertilizer
  • Implemented new reporting procedures with WDNR to maintain compliance with the facility’s WPDES permit
  • Developed a tracking procedure for hauled fertilizer


The resulting, first-of-its-kind fertilizer designation provides multiple benefits including:

  • Return valuable nutrients to crops while protecting soil and water resources
  • Minimize sludge sent to landfills year-round, even with a caked product
  • Significant cost savings related to sludge management.
  • In the first month of implementation, sludge hauling and disposal costs were reduced by nearly $30,000 with 88% less sludge being sent to a landfill

Focusing on the unique needs of every client and every project, The Probst Group was able to provide the ideal solution for the centralized treatment facility. Utilizing our team’s vast wastewater expertise and working closely with regulatory agencies allowed Probst to provide a first-of-its-kind regulatory pathway to reuse valuable nutrients produced during the wastewater treatment process to save an anticipated $100k+ in operating costs annually.

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