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 (Fe 3 O 4 ) 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 Fe 3 O 4 and ZVI during the whole anaerobic digestion of phenol. The phenol degradation rate and methane production of Fe 3 O 4 /ZVI-added group were increased by 8.8–23.1% and 11.9–31.6%, respectively compared with Fe 3 O 4 -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 hydrogenotrophic methanogens and Fe 3 O 4 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 Fe 3 O 4 and ZVI on the whole anaerobic phenol digestion.