Ecological analysis of the bacterial system in a full-scale egg-shaped digester treating sewage sludge

Gyokuyu Ri, O. Mizuno, T. Miyahara, T. Noike, K. Katsumata

Research output: Contribution to journalConference articlepeer-review

5 Citations (Scopus)


A full-scale investigation was conducted to evaluate the treatment performance and the bacterial system in an egg-shaped digester treating sewage sludge. The experiment was continued over one year to measure the methanogenic activities using various substrates and the population levels of various trophic groups of methanogenic bacteria, as well as the degradation of each component of organic matters. A total of 10 full-scale egg-shaped sludge digesters fed with concentrated sludge were investigated in this study. At a retention time of 30 days and mesophilic condition of 36°C, the average reduction efficiencies of carbohydrates, proteins and lipids, which are the three main components in raw sludge, were 74.2%, 55.2% and 42.2%, respectively. As a result, the removal efficiencies of volatile solids (VS) and total CODcr reached 54.2% and 60%, respectively, and 1 m3 influent concentrated sludge produced 23.3 m3 digestion gas in which methane content was about 60%. The comparison between the specific methanogenic activity and the actual specific methane production rate in the digester suggestes that the retention time of the digester could be reduced from 30 days to 15 days without affecting their performance. In addition, both the hydrogen and acetate-consuming methanogenic bacteria were enumerated on the order of 107 MPN/ml.

Original languageEnglish
Pages (from-to)471-478
Number of pages8
JournalWater Science and Technology
Issue number6-7
Publication statusPublished - 1997 Dec 17
Externally publishedYes
EventProceedings of the 1997 8th IAWQ International Conference on Anaerobic Digestion - Sendai, Jpn
Duration: 1997 May 251997 May 29


  • Activity
  • Anaerobic digestion
  • Bacterial population
  • Carbohydrate
  • Degradation
  • Egg-shaped digester
  • Lipid
  • Methanogenic bacteria
  • Protein
  • Sewage sludge

ASJC Scopus subject areas

  • Water Science and Technology


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