title: Bioconversion of high concentrations of hydrogen sulfide to elemental sulfur in airlift bioreactor.
abstract: Several bioreactor systems are used for biological treatment of hydrogen sulfide. Among these, airlift bioreactors are promising for the bioconversion of hydrogen sulfide into elemental sulfur. The performance of airlift bioreactors is not adequately understood, particularly when directly fed with hydrogen sulfide gas. The objective of this paper is to investigate the performance of an airlift bioreactor fed with high concentrations of H2S with special emphasis on the effect of pH in combination with other factors such as H2S loading rate, oxygen availability, and sulfide accumulation. H2S inlet concentrations between 1,008 ppm and 31,215 ppm were applied and elimination capacities up to 113 g H2S m(-3) h(-1) were achieved in the airlift bioreactor under investigation at a pH range 6.5-8.5. Acidic pH values reduced the elimination capacity. Elemental sulfur recovery up to 95% was achieved under oxygen limited conditions (DO < 0.2 mg/L) and at higher pH values. The sulfur oxidizing bacteria in the bioreactor tolerated accumulated dissolved sulfide concentrations >500 mg/L at pH values 8.0-8.5, and near 100% removal efficiency was achieved. Overall, the resident microorganisms in the studied airlift bioreactor favored pH values in the alkaline range. The bioreactor performance in terms of elimination capacity and sulfur recovery was better at pH range 8-8.5.
authors.affiliation: Department of Industrial Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia ; Department of Occupational Health and Air Pollution, High Institute of Public Health, Alexandria University, 165 El Horreya Avenue, Alexandria, Egypt.
authors.forename: Mohamed Abdel-Monaem
authors.initials: MA
authors.lastname: Zytoon
authors.affiliation: Department of Chemical and Material Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia.
authors.forename: Abdulraheem Ahmad
authors.initials: AA
authors.lastname: AlZahrani
authors.affiliation: Center of Excellence for Environmental Studies, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia.
authors.forename: Madbuli Hamed
authors.initials: MH
authors.lastname: Noweir
authors.affiliation: Department of Occupational Health and Air Pollution, High Institute of Public Health, Alexandria University, 165 El Horreya Avenue, Alexandria, Egypt.
authors.forename: Fadia Ahmed
authors.initials: FA
authors.lastname: El-Marakby
mesh_terms: D019149:Bioreactors; D006862:Hydrogen Sulfide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D010100:Oxygen; D013455:Sulfur / Q000737:chemistry*
chemical_list: D013455:Sulfur; D010100:Oxygen; D006862:Hydrogen Sulfide