Effect of HumicAcid-Heavy Metals on the Nitrogen Removal Performance of ANAMMOX Bacteria and Its Kinetic Analysis

Abstract

The effects of two typical heavy metal ions[Cu(Ⅱ) and Ni(Ⅱ)] and humic acid on ANAMMOX nitrogen removal (SAA) were studied through batch experiments, and the kinetic model was analyzed. At the same time, the effects of humic acid-heavy metal on ANAMMOX nitrogen removal were discussed. The results showed that ANAMMOX was promoted when ρ[Cu(Ⅱ)] and ρ[Ni(Ⅱ)] were 3 mg·L-1, and SAA was increased by 8.64% and 7.78%, respectively; ANAMMOX was inhibited when the ρ[Cu(Ⅱ)] and ρ[Ni(Ⅱ)] were 20 mg·L-1 and 5 mg·L-1, respectively, and the inhibition effect was more significant with the increase in heavy metal ion concentration. The index fitting showed that the IC50 of Cu(Ⅱ) and Ni(Ⅱ) on ANAMMOX were 29.67 mg·L-1 and 28.75 mg·L-1, respectively. SAA was increased by 7.37% when the ρ(humic acid) was 1 mg·L-1, and the inhibition rate reached 36.80% when the humic acid concentration was 40 mg·L-1. The linear fitting showed that the IC50 of humic acid on ANAMMOX was 58.36 mg·L-1. The modified Michaelis-Menten model could better describe the inhibitory kinetic behavior of heavy metals and humic acid on ANAMMOX. The model fitting showed that the complete inhibition concentrations (I*) of Cu(Ⅱ), Ni(Ⅱ), and humic acid on ANAMMOX were 49.59, 74.46, and 84.27 mg·L-1, respectively. An appropriate amount of humic acid was beneficial to improve the inhibition of heavy metals on ANAMMOX bacteria activity, and excessive humic acid would cause inhibition on ANAMMOX bacteria again.