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Removal of sulfur inorganic compounds by a biofilm of sulfate reducing and sulfide oxidizing bacteria in a down‐flow fluidized bed reactor
Author(s) -
CelisGarcía Lourdes B,
GonzálezBlanco Gehovana,
Meraz Mónica
Publication year - 2008
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.1802
Subject(s) - sulfur , sulfate , sulfide , chemistry , oxidizing agent , hydrogen sulfide , sulfate reducing bacteria , aeration , inorganic chemistry , organic chemistry
BACKGROUND: Biological sulfate removal is a process based on the biological sulfur cycle that consists of two steps: (1) production of sulfide by sulfate reduction; and (2) biological or physico‐chemical sulfide oxidation to elemental sulfur (S 0 ). The objective of this work was to transform soluble sulfur (sulfate) into insoluble sulfur (elemental sulfur) coupling sulfate reduction and sulfide oxidation in one reactor. To accomplish this, a 2.3 L down‐flow fluidized bed reactor was used. Lactate was supplied as electron donor, sulfate and oxygen (air) were the electron acceptors. RESULTS: After 55 days of batch operation a biofilm with sulfate reducing and sulfide oxidizing activities was developed over a plastic support. Continuous operation for 90 days at a down‐flow superficial velocity of 7.7 m h −1 and 30 °C, showed that sulfate reduction amounted to 72–77% and carbon removal to 20–31%. Under low aeration rates (2.3 L d −1 ) 50% of the sulfate was transformed to elemental sulfur, when aeration increased to 5.4 L d −1 elemental sulfur recovery was only 30% and sulfide in the effluent amounted to 27% of the sulfur fed. CONCLUSION: It was possible to obtain elemental sulfur through a coupled anaerobic/aerobic process in one reactor using lactate, sulfate and oxygen (air) as substrates. The development of a biofilm with sulfate reducing and sulfide oxidizing activities was the key of the process. Copyright © 2007 Society of Chemical Industry