Anaerobic Digestion of Napier Grass (Pennisetum purpureum) in Two-Phase Dry Digestion System Versus Wet Digestion System

Amornpan Thaemngoen, Kanyarat Saritpongteeraka, Shao Yuan Leu, Chettaphong Phuttaro, Chayanon Sawatdeenarunat, Sumate Chaiprapat

Research output: Journal article publicationJournal articleAcademic researchpeer-review

16 Citations (Scopus)


Napier grass (Pennisetum purpureum) is a high yield tropical grass with great potential for anaerobic digestion. Two-phase anaerobic dry digestion (TADD), considered an alternative for anaerobic wet digestion system (AWD) with only front-end leach bed reactor (LBR), is added to existing liquid digester, was tested under different leachate circulations, and was compared with AWD. Leachate circulation frequency in LBR was found to highly influence hydrolysis rate and hence improved overall digestibility of the grass fiber. Additional methane yield of 32.5% was achieved when leachate circulation increased from 1 to 4 times per day and diminished to merely 13.7% more at continuous circulation. A shift in methane generation from leachate digester to LBR as digestion time progressed and important biochemical characteristics were discussed. In AWD, operation at an organic loading of 4 kgVS/m3 d gave the highest methane yield at 145.2 m3/tondry, which is 2.3 times higher than TADD due to an advantage in mass transfer in a total wet environment. This work had advanced our understandings on phase separation in anaerobic digestion system and the key methanation performance among dry and wet digestions of the prototypical lignocellulosic biomass.

Original languageEnglish
Pages (from-to)853-865
Number of pages13
JournalBioenergy Research
Issue number3
Publication statusPublished - 1 Sept 2020


  • Dry digestion
  • Leachate circulation
  • Methane yield
  • Napier grass
  • Wet digestion

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Agronomy and Crop Science
  • Energy (miscellaneous)


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