Characterization and mechanism of the Cd(II) removal by anaerobic denitrification bacterium Pseudomonas sp. H117

Abstract

Toxic heavy metal containing Cd(II) species is a serious threat for ecological environmental and many aquatic organisms. This work is aimed at evaluating the performance of Cd(II) and nitrate removal by Pseudomonas sp. H117. Response surface methodology (RSM) experiments showed that the maximum Cd(II) removal efficiency of 85.67% was obtained under the optimum conditions: temperature of 30.48 °C, Mn(II) concentration of 52.13 mg L−1 and Cd(II) concentration of 12.78 mg L−1. The mechanism of Cd(II) removal was investigated, the results indicated that MnO2 adsorption and pH value increase were the main contributor to remove Cd(II). Moreover, meteorological chromatography analysis indicated that the characteristics of gas composition could be influenced by Cd(II). Sequence amplification identified the presence of the MCO (multicopper oxidase) gene in strain H117, indicating that the strain has the capacity to oxidize the Mn(II). XRD and SEM analysis confirmed that the oxide of Mn(II) was MnO2. XPS spectra indicated that the Cd(II) was adsorbed onto MnO2. These results indicated that strain H117 has the ability to perform simultaneous remove nitrate, Cd(II) and Mn(II), the process provided a potential for the treatment of complex polluted water.