Characterization of nutrients and pilot biofertilizer production from food waste and dairy manure digestates

Tyler J. Barzee, Abdolhossein Edalati, Joshua L. Rapport, Hamed M. El-Mashad, Ruihong Zhang

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Food waste and dairy manure digestates from commercial digesters were characterized in the lab for particle and nutrient distributions before pilot-scale processing (vibratory screen, ultrafiltration, sun drying) to produce solid and liquid biofertilizer products. Experimental results showed that the elemental compositions of the two digestates were different but shared similarities. The coarse solids of both digestates had lower concentrations of nutrients than the liquid fractions, which contained most of the K and Na. The dairy manure digestate had a higher amount of fine solids between 0.4 and 75 μm than the food waste digestate, but the majority of TKN was contained in the fine solids of both digestates. An optimization analysis concluded that optimal combinations of digestate fractions included over 70% coarse solids to obtain desired nutrient and salt ratios. The solid and liquid fertilizer products derived from the pilot-scale processing were similar to those expected from the lab-scale investigation.

Original languageEnglish
Pages (from-to)1153-1164
Number of pages12
JournalTransactions of the ASABE
Issue number4
StatePublished - 2021

Bibliographical note

Funding Information:
The authors wish to acknowledge Alan Kruger, Cindy Felber, and Sue Wise for their assistance with the study construction, data collection, and processing. This project was funded by appropriated funds from the USDA. The USDA is an equal opportunity provider and employer. The mention of trade names of commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA.

Funding Information:
The authors would like to thank the California Department of Food and Agriculture (CDFA) and the Central Valley Regional Water Quality Control Board for providing the funding for this project. We would also like to thank all of our collaborators from CleanWorld, New Hope Dairy, and UC Davis, including Caleb Adams, Dalton McKenzie, Don Morris, Arlin Van Groningen, Arlan Van Leeuwen, Tanner Garrett, Brandon Roosenboom, Ashwin Bala, and Yutao Liu, for their contributions. We also gratefully acknowledge the comments of three anonymous reviewers, which strengthened this article.

Publisher Copyright:
© 2021 American Society of Agricultural and Biological Engineers


  • Biofertilizer formulation
  • Digestate
  • Nutrient distribution
  • Pilot-scale processing
  • Ultrafiltration
  • Value-added products

ASJC Scopus subject areas

  • Forestry
  • Food Science
  • Biomedical Engineering
  • Agronomy and Crop Science
  • Soil Science


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