Effect of Dissolved Organic Matter on the Generation of H2O2 in Natural Biofilm Systems Under Illumination

The effects of dissolved organic matter (DOM) on the generation characteristics of hydrogen peroxide(H2O2) in natural biofilm systems were studied. The biofilm extracellular polymeric substances (EPS) and ethylenediamine tetraacetic acid (EDTA) were chosen as two typical DOM components. The results show that the presence of DOM has significant influences on the generation of H2O2. Illumination can promote EPS to produce H2O2 and EPS has no significant direct influences on generation of H2O2 by biofilms. H2O2 in the coexistence system is produced by both EPS and biofilms. EDTA doesn t produce H2O2 itself and has little influence on decomposition of H2O2, while showing significantly inhibition correlating to EDTA concentrations positively on the generation of H2O2 by biofilms. The pH value, DOM concentration and dissolved oxygen (DO) of the systems can varyingly affect the generation of H2O2 by EPS and the inhibition of EDTA on the generation of H2O2 in biofilms. Therefore, DOM has influences on both the generation of H2O2 in biofilms and the concentration of H2O2 in water environment, and the influences of different DOM components with different structures and properties may be significantly different.