Removal of sulfur inorganic compounds by a biofilm of sulfate reducing and sulfide oxidizing bacteria in a down-flow fluidized bed reactor
✍ Scribed by Lourdes B Celis-García; Gehovana González-Blanco; Mónica Meraz
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 2008
- Tongue
- English
- Weight
- 526 KB
- Volume
- 83
- Category
- Article
- ISSN
- 0268-2575
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✦ Synopsis
Abstract
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