LAUSR

Magnetite nanoparticles (Fe 3 O 4 NPs) were applied in an anaerobic semi-continuous tank reactor (ASTR) to investigate its effect on the anaerobic digestion (AD) of acetate synthetic wastewater. The Fe 3 O 4 NPs corrosion could create a more favorable micro-environment to enhance the methanogens activity. The chemical oxygen demand (COD) removal efficiency and methane production in test (ASTR T ) were 31.1% and 101.5% higher than those in control (ASTR C ). With the addition of Fe 3 O 4 NPs, the concentration of key coenzyme (F 420 and M) increased from averagely 0.523 and 5.352 μmol/g-VSS to 0.956 and 9.267 μmol/g-VSS, and the content of soluble microbial products (SMPs) significantly increased. Additionally, the high-throughput 16S rRNA gene sequencing further confirmed that the percentage of hydrogen-utilizing methanogens ( Methanolinea ) was up to 62.6% of total archaeal sequences. Fe 3 O 4 NPs addition would accelerate electrons transfer from acids oxidizers to syntrophic methanogenesis, further stimulate acids oxidizers to decompose acetate to H 2 /CO 2 , and finally facilitate more methane production.