The anaerobic treatment of low strength wastewaters in UASB and EGSB reactors

Mario T. Kato, Jim A. Field, Gatze Lettinga

Research output: Contribution to journalConference articlepeer-review

75 Scopus citations


The application of the UASB and EGSB reactors for the treatment of low strength wastewaters was investigated. The effect of dissolved oxygen on the methanogenic activity of granular sludges, the low substrate levels inside reactors and lower temperatures on the treatment performance were evaluated. The results showed that methanogens located in granular sludge have a high tolerance to oxygen. The concentration to cause 50% inhibition to methanogenic activity was between 7% and 41% oxygen in the head space of flasks, corresponding to 0.05 mg/l and 6 mg/l of DO prevailing in the media, respectively. The feasibility of UASB and EGSB reactors at 30°C was demonstrated. In UASB reactors, COD removal efficiencies exceeded 95% at organic loading rates up to 6.8 g COD/l.d and influent COD concentrations ranging from 422 to 722 mg/l, during the treatment of ethanol substrate. In EGSB reactors, efficiencies were above 80% at OLRs up to 12 g COD/l.d with COD as low as 100 to 200 mg/l. The studies confirmed that in practice DO does not constitute any detrimental effect on the reactor treatment performance. Lowering the temperature down to 15°C in EGSB reactors also showed that the potentials of anaerobic technology can be further explored in the treatment of dilute wastewaters.

Original languageEnglish (US)
Pages (from-to)375-382
Number of pages8
JournalWater Science and Technology
Issue number6-7
StatePublished - 1997
EventProceedings of the 1997 8th IAWQ International Conference on Anaerobic Digestion - Sendai, Jpn
Duration: May 25 1997May 29 1997


  • Anaerobic granular sludge bed
  • Ethanol
  • Low strength wastewater
  • Low temperature
  • Methanogenic activity
  • Oxygen toxicity
  • UASB and EGSB reactors
  • Whey

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology


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