Two-stage biogas production by co-digesting molasses wastewater and sewage sludge

Jung Yeol Lee, Jeonghee Yun, Tae Gwan Kim, Daehyun Wee, Kyung Suk Cho

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24 Scopus citations


We evaluated the feasibility of co-digesting molasses wastewater and sewage sludge in a two-stage hydrogen- and methane-producing system. The highest energy was recovered at the 21-h hydraulic retention time (HRT) of the first hydrogenic reactor and at 56-h HRT of the secondary methanogenic reactor. Hence, the two-stage system recovered 1,822 kJ from 1 L of the mixed wastes (19.7: hydrogenic reactor plus, 1,802 kJ L-1: methanogenic reactor). Despite the overloaded VFA-run with a short HRT of 56 h, the GAC-CH4 reactor increased methane production rate and yields due to enhanced pH buffer capacity. An RNA-based community analysis showed that the Ethanoligenens and Methanosaeta dominated the hydrogen and methane bioreactor, respectively. The two-stage system of co-digesting molasses and sewage sludge is particularly cost-effective due to non-pretreatment of sewage sludge.

Original languageEnglish
Article number1217
Pages (from-to)2401-2413
Number of pages13
JournalBioprocess and Biosystems Engineering
Issue number12
StatePublished - 5 Nov 2014

Bibliographical note

Publisher Copyright:
© 2014 Springer-Verlag Berlin Heidelberg.


  • Co-digestion
  • Hydrogen
  • Methane
  • Molasses
  • Sewage sludge


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