Structure modification and extracellular polymeric substances conversion during sewage sludge biodrying process

Lu Cai, Thomas Krafft, Tong-Bin Chen*, Ding Gao, Li Wang

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

24 Citations (Web of Science)


Biodrying, an economical and energy-saving biomass waste treatment, removes water from waste using the biological heat generated by organic matter degradation. Technical limitations associated with dewatering complicate the biodrying of sewage sludge. This study investigated the sludge alteration associated with its water removal, focusing on sludge form, extracellular polymeric substances, and free water release. An auto-feedback control technology was used for the biodrying; a scanning electron microscope was used to record the morphological change; three-dimensional excitation-emission matrix fluorescence spectroscopy was used to analyze extracellular polymeric substances ( EPS) variation, and time domain reflectometry was used to assess the free water release. Over the 20-day biodrying, there was a 62% water removal rate during the first thermophilic phase. Biodrying created a hollow and stratified sludge structure. Aromatic proteins and soluble microbial byproducts in the EPS were significantly degraded. The thermophilic phase was the phase resulting in the greatest free water release.
Original languageEnglish
Pages (from-to)414-421
JournalBioresource Technology
Publication statusPublished - Sept 2016


  • Biodrying
  • Extracellular polymeric substances
  • Free water
  • Morphological change
  • Sewage sludge

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