Improving solids retention in upflow anaerobic sludge blanket reactors at low temperatures using lamella settlers

Maha M. Halalsheh, Hussien H. Muhsen, Khaldoun M. Shatanawi, Jim A. Field

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Lamella settlers were used to increase sludge concentration in pilot scale UASB reactors treating concentrated sewage at low temperature. The aim was to increase sludge retention time (SRT) and achieve better digestion in UASB reactors without the need for increasing the hydraulic retention time (HRT). Two modified UASB reactors were used for this purpose. In the first reactor, lamella settlers were installed in the settling zone of the UASB reactor and the reactor was named UASB-ESR1. In the second reactor, lamella settlers were installed underneath the gas liquid separator (GLS) and the reactor was named UASB-ESR2. The sludge concentration, sludge profile, and system performance of each reactor were monitored. The obtained sludge concentrations were 50 and 53 g TS/l for UASB-ESR1 and UASB-ESR2, respectively. The measured concentrations were almost double the concentrations reported for conventional UASB reactors ranging 16-26 g TS/l. The calculated SRT in the modified UASB reactors was 103 days in both reactors. The average total COD (CODtot) and suspended COD (CODss) removal efficiencies were 38% and 60%, respectively for the UASB-ESR1. The average CODtot and CODss removal efficiencies for the UASB-ESR2 were 41% and 62%, respectively. The modified reactors were considered at the startup period and the performances of the modified systems are expected to significantly improve when arriving at steady state conditions.

Original languageEnglish (US)
Pages (from-to)1054-1059
Number of pages6
JournalJournal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering
Issue number9
StatePublished - Jan 2010


  • Lamella settlers
  • Low temperature
  • Sludge concentration
  • UASB reactor performance

ASJC Scopus subject areas

  • Environmental Engineering


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