The effect of wastewater components and operation conditions on selenium release during desulfurization wastewater evaporation: A lab-scale study

Abstract

Rotary atomization evaporation technology is one of the effective technologies to achieve zero discharge of desulfurization wastewater. However, the migration and transformation mechanism of selenium during desulfurization wastewater evaporation is still unknown, hindering this technology's further application. Therefore, the effects of evaporation temperature, pH, Cl−, S2O2–8, SO2–4and Ca2+ on selenium release during evaporation were investigated in this work. The results showed that elevated temperature promoted the release of selenium, especially in the solid-phase pyrolysis stage. pH affected the release of selenium through influencing its initial species, and the release rate of Se(IV) increased with decreasing pH. The ionic compositions of the solution were also found to be a critical factor in the stability of selenium species during evaporation. Cl− would promote the release of Se(IV), while SO2–4 inhibited the release of selenium species, and Ca2+ had little effect on the final release rate of selenium species release. In addition, it was found that the presence of S2O2–8 would significantly enhance the conversion of Se(IV) to Se(VI) during the evaporation process. The results obtained in this work provided guidelines and suggestions for controlling the selenium release from desulfurization wastewater in power plants.