Treatment of digestate residues for energy recovery and biochar production: From lab to pilot-scale verification

Chunxing Li, Jie Li, Lanjia Pan, Xinyu Zhu, Shengyu Xie, Guangwei Yu, Yin Wang*, Xiaofang Pan, Gefu Zhu, Irini Angelidaki

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Hydrothermal pretreatment was used for dewatering food waste digestate residue, and biochar/biogas were generated from the separated solid and liquid phases via pyrolysis and anaerobic digestion, respectively. Increasing hydrothermal pretreatment temperature (110–200 °C) clearly improved dewaterability, whereas enhancing treatment duration (30–90 min) had little impact. The optimal condition of 160 °C/30 min gave the best dewatering performance with relative lower energy consumption and was chosen for pilot-scale verification achieving 61.7 wt% dry weight content after mechanical squeezing. Moreover, the filtrate and filter cake obtained at optimal condition were applied for biogas and biochar production in lab scale. The methane yield of the filtrate was 335 mL/g COD. Pyrolysis temperature of 500 °C gave better biochar performance and was verified in a pilot scale test. Additionally, the heavy metals in digestate were effectively immobilized during hydrothermal dewatering and pyrolysis processes. In the end, mass/energy balance calculated using pilot-scale data presented the combined systems provided a promising strategy for accomplishing energy recovery and resource reuse of digestate residue.

Original languageEnglish
Article number121852
JournalJournal of cleaner production
Volume265
Number of pages12
ISSN0959-6526
DOIs
Publication statusPublished - 2020

Keywords

  • Biochar
  • Dewaterability
  • Digestate residue
  • Energy
  • Mass balance
  • Pilot scale

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