Notice of RetractionSulfate and Heavy Metals Removal in a Sulfate Reducing Bioreactor Treating Mildly Acidic Wastewater

Notice of Retraction

After careful and considered review of the content of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE´s Publication Principles.

We hereby retract the content of this paper. Reasonable effort should be made to remove all past references to this paper.

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A synthetic mildly acidic wastewater containing 47.1 mg Zn²⁺/L, 19.8 mg Cu²⁺/L, 5.0 mg Cr³⁺/L, and 4.0 g SO₄^2-/L was treated using a sulfate-reducing bioreactor. A laboratory-scale continuous-flow stirred tank reactor was applied. The results showed that the sodium lactate-supplemented sulfate-reducing process resulted in the effluent pH increase from ~5.0 to ~8.0, nearly complete sulfate reduction, and metal removal efficiencies greater than 99% for Zn and Cu, and >;89% for Cr, respectively. Changing the concentration of sodium lactate from 17 to 4.0 g/L (i.e. the decrease of chemical oxygen demand (COD)/SO₄^2- ratio from 3.0 to 0.78) decreased greatly the percentage of sulfate reduction from ~100 to ~15%, but had no adverse influence on the final efficiencies of metals removal. The ability of this process to effectively remove sulfate and heavy metals makes it particularly attractive for the treatment of these contaminated aqueous streams similar to acid mine drainage.