The research focused on the production of a complex wastewater coagulant containing polymeric sulfates of aluminum and iron from fly ash. At the same time, SO2 in the simulated flu gas was removed by absorption in a fly ash slurry and oxidized with sodium chlorate. Extraction efficiency of iron and aluminum oxides from fly ash was affected greatly by reaction temperature and time. The extraction efficiency increases as temperature increases. Removal efficiency of SO2 was influenced by temperature, SO2 feed concentration and feed gas dispersing method. The produced complex coagulant containing both polymeric ferric sulfate (PFS) and polymeric aluminum sulfate (PAS) was proven to be effective in removing total suspended solids (TSS) and turbidity in wastewater. The complex coagulant is more effective than conventional iron and aluminum sulfates in turbidity removal. (C) 2008 Elsevier B.V. All rights reserved.