Pilot Project for Value-Added Product Development from Solid ...

While the full-scale vermicomposting facility was being designed and built a small-scale
experiment was established at North Carolina State University’s Lake Wheeler Road Field
Laboratory to collect preliminary data on vermicompost physical and chemical properties
and the potential for pathogen reduction in the finished material. During a 12-month
period, over 5,200 pounds of separated swine solids were added to a worm bin at a rate of
approximately 0.3 pounds per square foot of bed surface area. Approximately 1,560
pounds of castings were collected from the small-scale bed. The recovered castings
contained approximately 42% of the nitrogen and 82% of the phosphorus that was present
in the waste material originally applied. The vermicomposting of the small-scale bed also
provided a 3-log reduction in the number of bacterial indicators for which analysis was
conducted, including fecal coliform, E. coli, and enterocci. Because the criteria for the
EST determination requires a 4-log reduction 8 , an additional treatment will likely be
required to meet the EST requirement as well as the new performance standards.
NatureWorks Organics already adds a drying step at its centralized process facility that
may provide additional treatment. The potential for additional treatment benefits will be
verified during the full-scale evaluation that will occur once worm castings become
available for analysis by North Carolina State University.
Funding
Of the grant funding, $83,700 was used to design and construct the on-farm
vermicomposting system. In addition, NatureWorks Organics contributed $190,000
toward the project, including project management costs, the purchase of worms, and
$52,000 in funding provided to North Carolina State University for the environmental
performance verification of the system.
8 This requirement specifically applies to the terms of the Smithfield Agreement.
9