Abstract: The effect of different concentration of Fe²⁺ on the activity of anaerobic ammonium oxidation sludge was experimentally investigated by the addition of anammox sludge in stable operation at reactor. The experimental results show that: Fe²⁺ can promote cell synthesis of anaerobic ammonia oxidation bacteria and increase its matrix metabolism， through 210 days continuous operation. When the concentration of Fe²⁺ in the solution is 0.085mmol/L (4.76mg/L)， the ammonia nitrogen conversion rate remains at more than 90%. The heme content of anaerobic ammonia oxidation bacteria is increased by the addition of Fe²⁺. At this point， the heme C content reaches 0.143μmol/mg in the sample. It is 2.04 times heme content of anaerobic ammonia oxidation bacteria in comparison reactor at the same period. It is found that using SEM when the concentration of Fe²⁺ is 0.085mmol/L， the anaerobic ammonia oxidation bacteria form approaches to a steady state.

Key words: anaerobic ammonium oxidation(anammox), Fe³⁺, heme content, SEM, Fe²⁺