Synergistic effect of magnetite and zero-valent iron on anaerobic degradation and methanogenesis of phenol

Anaerobic digestion is widely employed for treating phenol-containing wastewater, but there are still some drawbacks such as slow phenol degradation rate and vulnerable acetoclastic methanogens. Coupling of magnetite (Fe3O4) and zero valent iron (ZVI) was firstly used to enhance anaerobic digestion of phenol. The results indicated an obvious synergistic effect was generated with coupling of Fe3O4 and ZVI during the whole anaerobic digestion of phenol. The phenol degradation rate and methane production of Fe3O4/ZVI-added group were increased by 8.8-23.1% and 11.9-31.6%, respectively compared with Fe3O4-added group, and enhanced by 5.9-17.1% and 4.4-18.3%, respectively compared with ZVI-added group. ZVI improved the growth of hydro-genotrophic methanogens and Fe3O4 enhanced the growth of syntrophic acetate-oxidizing bacteria. Finally, the syntrophic interaction between acetate-oxidizing bacterium and hydrogenotrophic methanogens played a vital role on the synergistic effect of Fe3O4 and ZVI on the whole anaerobic phenol digestion.