Upgrading of anaerobic digestion of waste activated sludge by temperature-phased process with recycle

Li Jie Wu, Yu Qin, Toshimasa Hojo, Yu You Li

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


Thermophilic (55°C)-mesophilic(35°C) and hyper-thermophilic(70°C)-mesophilic TPAD-R (temperature-phased anaerobic digestion with recycle) were conducted to compare and evaluate the operation performance to treat WAS (waste activated sludge) with the MD (conventional mesophilic anaerobic digestion). TPAD-R was based on the TPAD (temperature-phased anaerobic digestion), and introduced a recycle system from the end mesophilic stage to the front stage. Thermophilic-mesophilic TPAD-R produced more biogas 0.99L/g VS (volatile solids) reduced/d than MD 0.83L/g VS reduced/d. In thermophilic-mesophilic TPAD-R 35.7% and 18.7% of WAS was converted to methane in the thermophilic stage and in the mesophilic stage, respectively, according to a COD balance. Solids reduction was improved to a similar extent in thermophilic-mesophilic TPAD-R and hyper-thermophilic-mesophilic TPAD-R, which was 10% higher than that in MD (approximately 40% of VS reduction). Hydrolysis, acidogenesis and methanogenesis analysis indicated that thermophilic and hyper-thermophilic stage accelerated the hydrolysis rate of TPAD-R, 0.053gCOD/gVS/d and 0.040gCOD/gVS/d, respectively, compared to about 0.025gCOD/gVS/d in MD. In addition, thermophilic-mesophilic TPAD-R achieved more surplus energy than hyper-thermophilic-mesophilic TPAD-R and MD.

Original languageEnglish
Pages (from-to)381-389
Number of pages9
Publication statusPublished - 2015 Jul 1


  • Anaerobic digestion
  • Hyper-thermophilic
  • Recycle
  • Temperature-phased anaerobic digestion
  • Two-stage
  • Waste activated sludge

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Pollution
  • Mechanical Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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