Abstract: We investigated the effects of adding ionic state, complex state and oxidation state of iron o r manganese on generation of H₂O₂ and degrada tion of sodium dodecyl benzene sulfonate (SDBS) in natural water biofilm systems under illumination via the simulation experiment, and analyzed the mechanism of degradation of SDB S in the system. The results indicate that different forms of iron or manganes e can promote degradation of SDBS in the system, and the concentration of H₂O ₂ decreases firstly and then increases in the system. Effects of different for ms of iron or manganese are small. The effect of ionic state is relatively str ong, and the effect of oxidation state is relatively week. The effect of adding iron is more obvious than that of adding manganese.

Key words: manganese, iron, reactive oxygen species, sodium dodecyl benzene sulfonate （SDBS）, natural water biofilm, degradation