Process for Removing Selenium from Wastewater Using Biological Reduction and Surface Complexation

A process for removing selenium from water is described. Through a biological reduction process, selenium +6 species are reduced to selenium +4 species. A coagulant is mixed with the water and as a result, solids having complexation binding sites are formed. The reduced selenium +4 species is adsorbed onto the complexation binding sites of the solids. Thereafter, the solids having adsorbed selenium +4 species is separated from the water and ultimately separate from the process. The resulting effluent is subjected to a second biological treatment under aerobic conditions which converts residual selenium and organo-selenium to selenate.