Regulating intermediates to realize the coupled hydrion with biology polysulfide in wastewater treatment

Abstract

The purpose of this study is to clarify the mechanism of the coupled hydrion with biology polysulfide in the simultaneous denitrification and desulfurization process. The coupled hydrion with biology polysulfide, uncoupled hydrion with biology polysulfide and no polysulfide experiments were performed in wastewater with two kinds of sulfide loads (100 and 200 mg/L). When the concentration of thiosulfate was suitable, the free H⁺ concentration (74.2 and 91.0 mg/L) and the proportion of Thiobacillus denitrificans (85.4% and 59.7%) were both higher under the two kinds of sulfide loading conditions (100 and 200 mg/L), and coupled hydrion with biology polysulfide was realized (the production of elemental sulfur is as high as 33 and 101 mg/L). Further analysis shown that the way of coupled hydrion with biology polysulfide were both: $2.0S^{2-}+6{.4\mathrm{NO}}_3^{-}+30.1H^{+}+21.7e^{-}\to 1.0S^{2-}+1{.0\mathrm{SO}}_4^{2-}+3.2N_2+15.0H_{2}O$. In addition, for the coupled hydrion with biology polysulfide, more nitrates could be utilized to produce elemental sulfur S⁰, and the lower ratio of H⁺/S⁰ and ${\mathrm{SO}}_4^{2-}/S^0$ were observed (S^2- = 100 mg/L: 2.3 and 0.9; S^2- = 200 mg/L: 0.9 and 0.03), which could promote the growth of Thiobacillus denitrificans and increase the proportion of Thiobacillus denitrificans. This maybe one of the reasons why coupled hydrion with biology polysulfide could be achieved.

Keywords: Coupled hydrion with biology polysulfide; Thiobacillus denitrificans; elemental sulfur; simultaneous denitrification and desulfurization; wastewater treatment.