American Society of Civil Engineers


Effect of Aeration on the Quality of Effluent from UASB Reactor Treating Sewage


by Abid Ali Khan, (corresponding author), (Doctoral student, Dept. of Civil Engineering, Indian Institute of Technology, Roorkee, India. E-mail: abidkdce@iitr.ernet.in; dee.abid@gmail.com), Rubia Zahid Gaur, (Senior Research Fellow, Dept. of Civil Engineering, Indian Institute of Technology, Roorkee, India.), Beni Lew, (Researcher Scientist, ARO—The Volcani Center, Institute of Agriculture Engineering, P.O. Box 6, Bet Dagan, 50250, Israel.), Indu Mehrotra, (Professor, Dept. of Civil Engineering, Indian Institute of Technology, Roorkee, India.), and A. A. Kazmi, (Associate Professor, Dept. of Civil Engineering, Indian Institute of Technology, Roorkee, India.)

Journal of Environmental Engineering, Vol. 137, No. 6, June 2011, pp. 464-471, (doi:  http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000348)

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Document type: Journal Paper
Abstract: 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 30 min 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 H2 S 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.


ASCE Subject Headings:
Sewage
Oxygen
Mass transfer
Coefficients
Sulfides
Sulfates
Aeration

Author Keywords:
UASB effluent
Surface and diffused aeration
Oxygen mass transfer coefficient (KLa)
DO
Sulfide and sulfates
STP