Impact of digestate and its fractions on mineralization of 14C-phenanthrene in aged soil

Cynthia Ibeto, Victor Omoni, Micheal Fagbohungbe, Kirk Semple

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Abstract

The impact of whole digestate (WD) and its fractions (solid [SD] and liquid [LD]) on 14C-phenanthrene mineralization in soil over 90 d contact time was investigated. The 14C-phenanthrene spiked soil was aged for 1, 30, 60 and 90 d. Analysis of water-soluble nitrogen, phosphorus, total (organic and inorganic) carbon, and quantitative bacterial count were conducted at each time point to assess their impact on mineralization of 14C-phenanthrene in soils. Indigenous catabolic activity (total extents, maximum rates and lag phases) of 14C-phenanthrene mineralization were measured using respirometric soil slurry assay. The soil amended with WD outperformed the SD and LD fractions as well as showed a shorter lag phase, higher rate and extent of mineralization throughout the study. The digestates improved (P < 0.05) the microbial population and nutritive content of the soil. However, findings showed that spiking soil with phenanthrene generally reduced the growth of microbial populations from 1 to 90 d and gave a lower nutritive content in comparison with the non-spiked soil. Also, soil fertility and bacteria count were major factors driving 14C-phenanthrene mineralization. Particularly, the non-phenanthrene degraders positively influenced the cumulative mineralization of 14C-phenanthrene after 60 d incubation. Therefore, the digestates (residue from anaerobic digestion) especially WD, which enhanced 14C-phenanthrene mineralization of the soil without minimal basal salts medium nor additional degraders should be further exploited for sustainable bioremediation of PAHs contaminated soil.
Original languageEnglish
Article number110482
Number of pages8
JournalEcotoxicology and Environmental Safety
Volume195
Early online date19 Mar 2020
DOIs
Publication statusE-pub ahead of print - 19 Mar 2020

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Keywords

  • Soil fertility
  • Phenanthrene
  • Mineralization
  • Degraders
  • Heterotrophs
  • Digestate

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