Amoxicillin was used as the research object to investigate the effects of heterogeneous Fenton-like pre-treatment on the physicochemical properties and microbial community structure of activated sludge after different degrees of magnetic nano-iron (Fe3O4 NPs). The results showed that with increasing the pre-treatment degrees (without pre-treatment

with 40% H2O2 and 60% H2O2)

the average COD removal rate increased from 81.5% to 89.1%

and the average ammonia nitrogen removal rate increased from 86.2% to 95.6% by the activated sludge. Meanwhile

the protease content increased from 0.13 mg·g-1 to 0.19 mg·g-1 in the activated sludge. With the increase of pre-treatment degrees

three-dimensional excitation emission matrix (EEM) spectra demonstrated that the absorption peaks of the fulvic acids and humic acids in the visible region were gradually decreased in the soluble microbial products (SMP) of the activated sludge. It was showed that the activated sludge had good activity. In addition

the abundance of Proteobacteria was 73.81%

84.08%

77.08%

and the abundance of Firmicutes was 0.6%

0.82%

0.78% at without pre-treatment

with 40% H2O2 and 60% H2O2 pre-treatment condition

respectively. Proteobacteria was the dominant bacteria species. Many nitrogen-fixing bacteria and phosphorus-accumulating bacteria belong to Proteobacteria. Meanwhile

Firmicutes could use hydrolytic enzymes to degrade proteins and sugars. The increase of the proportion of Proteobacteria and Firmicutes had provided a guarantee for the efficient removal of pollutants in the wastewater.