Effect of aeration on the quality of effluent from UASB reactor treating sewage

Abid Ali Khan, Rubia Zahid Gaur, Beni Lew, Indu Mehrotra, A. A. Kazmi

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


The treatment of effluent of pilot- and full-scale upflow anaerobic sludge blanket (UASB) reactors operating at steady state was studied in an aeration-settling system. The fine pore submerged diffusers were used to aerate the effluent of UASB reactors under different operating conditions. Forty to 55% of the biochemical oxygen demand (BOD) and the chemical oxygen demand (COD) removal efficiencies were achieved by the direct aeration of the UASB effluent in the laboratory. The maximum removal efficiencies were achieved at 30min hydraulic retention time (HRT) and a dissolved oxygen (DO) of 5-6 mg/L or high KLa (vigorous aeration). Batch experiments on nitrogen purging and the aeration of sulfides, volatile organic compounds (VOCs), and nonpurgeable organic carbons (NPOCs) were performed to ascertain the mechanism of BOD/COD removal. During aeration, BOD and COD were reduced by the stripping of H 2S and VOCs and by the chemical oxidation of total sulfides and organic carbon. The stripping and chemical oxidation depended on the HRT and DO. The performance of a full-scale surface aeration system was compared to the performance of a pilot-scale diffused aeration system. Final sedimentation was effective only in removing the solids from the effluent of the aeration system. The results were confirmed by organic mass balance.

Original languageEnglish
Pages (from-to)464-471
Number of pages8
JournalJournal of Environmental Engineering (United States)
Issue number6
StatePublished - Jun 2011
Externally publishedYes


  • Aeration
  • Coefficients
  • DO
  • Mass transfer
  • Oxygen
  • Oxygen mass transfer coefficient (K a)
  • STP
  • Sewage
  • Sulfates
  • Sulfide and sulfates
  • Sulfides
  • Surface and diffused aeration
  • UASB effluent


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