Sulfur transformation in sulfur autotrophic denitrification using thiosulfate as electron donor

Fan, Chunzhen; Zhou, Weili; He, Shengbing; Huang, Jungchen

Sulfur transformation in sulfur autotrophic denitrification using thiosulfate as electron donor

2021

Fan, Chunzhen | Zhou, Weili | He, Shengbing | Huang, Jungchen

Thiosulfate is frequently used as an energy source and electron donor in autotrophic denitrification (AD) for removing nitrate from wastewater. However, transforming pathways of S₂O₃²⁻ in this process is unclear. Herein, the aim of this study is to explore possible transforming pathways of sulfur compounds in thiosulfate-based AD process. After measuring the variation of NO₃⁻, NO₂⁻, and various sulfur compounds such as S⁰, SO₄²⁻, S₂O₃²⁻, acid volatile sulfide (AVS), and S²⁻ in the presence and absence of S₂O₃²⁻, the variation process of S₂O₃²⁻ and the contribution of various sulfur compounds were analyzed. The results indicated that S⁰, AVS, and S²⁻ were the intermediate products when S₂O₃²⁻ was applied as an electron donor. All S₂O₃²⁻, S⁰, AVS, and S²⁻ could act as electron donors in the nitrate removal process with the final products of SO₄²⁻. The utilization priority of these four sulfur sources was presumed in the following order: S²⁻ > S₂O₃²⁻ > AVS ≈ S⁰. Furthermore, sulfur transformation and balance in nitrate removal process was also investigated. This suggests the transforming pathways of sulfur compounds in denitrification process. Nitrogen removal and sulfur conversion process are dependent on the presence of microorganisms in the sludge.

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