Flue gas desulfurization by FeSO4 solutions and coagulation performance of the polymeric ferric sulfate by-product

A process for flue gas desulfurization (FGD) with simultaneous polymeric ferric sulfate (PFS) production was investigated, using a ferrous sulfate (FeSO4) solution as the absorbent, sulfur dioxide (SO2) in flue gas as the raw material and sodium chlorate (NaClO3) as the oxidant. The results indicate that SO2 removal efficiency in a packed column could be maintained at a high level, with an average value of more than 95% during experiments. Liquid PFS that met established quality standard was produced simultaneously. Meanwhile, the solid PFS by-products would be obtained in a spray-drying column due to the high temperature inlet flue gas and its quality parameters were determined. The liquid and solid PFS by-products were used to treat three types of wastewater, and it is found that two types of synthesized PFS were close or better than commercially available solid PFS for chemical oxygen demand (COD) removal and the performance of liquid PFS was found to be superior to that of solid PFS.