Kinetic analysis and mechanism of nitrate, calcium, and cadmium removal using the newly isolated Pseudomonas sp. LYF26

The co-existence of heavy metals and nitrate (NO3−-N) pollutants in wastewater has been a persistent global concern for a long time. A strain LYF26, which can remove NO3−-N, calcium (Ca(II)), and cadmium (Cd(II)) simultaneously, was isolated to explore the properties and mechanisms of synergistic contaminants removal. Different conditions (Cd(II) and Ca(II) concentrations and pH) were optimized by Zero-, Half-, and First-order kinetic analyses to explore the environmental parameters for the optimal effect of strain LYF26. Results of the kinetic analyses revealed that the optimal culture conditions for strain LYF26 were pH of 6.5, Cd(II) and Ca(II) concentrations of 3.00 and 180.00 mg L−1, accompanied by Ca(II), Cd(II), and NO3−-N efficiencies of 53.10%, 90.03%, and 91.45%, respectively. The removal mechanisms of Cd(II) using strain LYF26 as a nucleation template were identified as biomineralization, lattice substitution, and co-precipitation. The differences and changes of dissolved organic matter during metabolism were analyzed and the results demonstrated that besides the involvement of extracellular polymeric substances in the precipitation of Cd(II) and Ca(II), the high content of humic acid-like species revealed a remarkable contribution to the denitrification process. This study is hopeful to contribute a theory for further developing microbially induced calcium precipitation used to treat complex polluted wastewater. [Display omitted] •A novel strain LYF26 was isolated for efficient removal of NO3−-N, Ca(II) and Cd(II).•Growth conditions of strain LYF26 were optimized by Zero-, Half-, and First-models.•Cd(II) in the form of CdCO3 and Cd3(PO4)2 was removed via the MICP process.•Valuable application of MICP process in denitrification and heavy metal removal.