• Meridian Bridge

    Winter Scene

  • Fire Prevention Week

    Fire Prevention Week

  • Lewis & Clark Lake

    Lewis & Clark Lake

  • Yankton 4th of July Fireworks

    Yankton's annual 4th of July fireworks show over the Missouri River.

  • Jim River Bridge

    Jim River Bridge

  • Lake Area Trail

    Lake Area Trail

  • Meridian Bridge Moonlight

    Meridian Bridge Moonlight

  • Lewis & Clark Recreation Area

    Lewis & Clark Recreation Area

  • Walnut Street

    Walnut Street

  • Bragging Rights

    Bragging Rights

  • Downtown Streetscape

    Yankton's Downtown

  • Lewis & Clark Lake

    Missouri River Bluffs

  • 4th of July

    4th of July Fireworks Show

  • Riverside Park

    Riverside Park

  • Meridian Bridge Fog

    Meridian Bridge Fog

  • Meridian Bridge Winter

    Meridian Bridge Winter

  • Meridian Bridge Fall

    Yankton Meridian Bridge Fall

  • Lewis & Clark Lake

    Lewis & Clark Lake walking trails.

  • Rockin' Ribfest

    June 3-4

  • Yankton Marina

    Yankton Marina

  • Yankton Missouri River

    Yankton Missouri River

  • Fishing the Missouri

    Missouri River Yankton

  • Meridian Bridge

    Meridian Bridge

  • Ice Sailing

    Missiouri River Ice Sailing

  • Yankton Riverside Park Winter View

    Yankton Riverside Park Winter View

  • Missouri River Yankton

    Merry Christmas

  • Yankton Discovery Bridge

    Yankton Discovery Bridge

Biosolids Recycling Process

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Wastewater Digester

Biosolids are captured in the primary clarification process and fed to two anaerobic digesters that operate in series.  The anaerobic digesters are filled with trillions of acid and methane producing microscopic bacteria.  Anaerobic digestion is one of nature’s greatest tools because the result is a net reduction of biosolids.  This means that at the end of the process there are less biosolids than originally went into the system.  The methane byproduct produced by the bacteria is captured and recycled as natural gas to heat their environment to the required 95°F.  The biosolids are broken down and digested by the bacteria for over 60 days in the anaerobic digesters.  

After digestion, the sludge is pumped to the lagoon system.  The biosolids are further digested and broken down to a safe pathogen free product.  The water is removed and treated separately at the Wastewater Treatment Plant before discharge in the Missouri River.  The biosolids remain in the lagoons until fall, when they are sampled and tested for metal pollutants, nitrogen, phosphorous and potash. 

The Wastewater Treatment Plant staff then sample the soil of the agricultural property that will receive the biosolids.  The soil is sampled in each soil profile to a depth of five feet in one foot increments to test each layer of soil for the background nitrogen, phosphorous, and potash levels in the field.

Once staff receives the test results for the biosolids and the soils, the agronomic rate is calculated according to the background soil nutrient levels, the biosolids nutrient levels, and based on the next year's planned crop type (each crop has a unique nutrient uptake need).   A 10% safety factor is calculated into the agronomic rate for the biosolids application.

The land application of biosolids is carried out annually by a private contractor selected by public bid process.  Waterwater Treatment Plant staff are responsible for oversight and ensuring the correct procedure and application of the biosolids to the agricultural land. 

All of these activities are completed under the regulation of the South Dakota Department of Environment and Natural Resources, South Dakota Water Pollution Control Act, and with the appropriate permits.  The land application of biosolids is carefully regulated, and the City of Yankton’s Biosolids Management Plan under Permit No SDL023396 provides additional details about the testing and application process.

Kyle Goodmanson, Director of Environmental Services 
315 West Riverside Drive
PO Box 176
Yankton, SD 57078
Phone: (605) 668-5270

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