Post-digestate composting benefits and the role of enzyme activity to predict trace element immobilization and compost maturity

Bioresour Technol. 2021 Oct;338:125550. doi: 10.1016/j.biortech.2021.125550. Epub 2021 Jul 13.


The current study evaluated the quality of agricultural waste digestate by composting or co-composting with biogas feedstock (maize silage, food processing waste, or poultry litter). Temperature, phytotoxicity, C/N ratio, water extractable trace elements, and 14 enzyme activities were monitored. Temperature dropped earlier in digestate and maize silage co-composting pile, reducing time to maturity by 20 days. Composting and co-composting reduced phytotoxicity and C/N ratio, but increased immobilization of Al, Ba, Fe, Zn, and Mn at least by 40% in all piles. All the enzyme activities, except arylsulfatase and α-glucosidase, increased at the maturity phase and negatively correlated with organic matter content and most of trace elements. Post-digestate composting or co-composting with biogas feedstock is a promising strategy to improve digestate quality for fertilizer use, and selected enzyme activities can be indicators of compost maturity and immobilization of trace elements.

Keywords: C/N ratio; Compost maturity; Food processing waste; Maize silage; Poultry litter.

MeSH terms

  • Composting*
  • Fertilizers / analysis
  • Silage
  • Soil
  • Trace Elements*


  • Fertilizers
  • Soil
  • Trace Elements