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The basification method was used for the optimized preparation of a new flocculant, poly‐ferric aluminum phosphate sulfate (PPFAS). The Ferron method was used to analyze the distributions of the Fe and Al forms in PPFAS. The conditions of the optimized preparation of PPFAS were as follows: the n(OH)/n(Fe) ratio of 0.6, the n(P)/n(Fe) ratio of 1/5, and the reaction temperature of 60°C. After each addition of NaOH and Na3PO4, the reaction was allowed to proceed for 10 min, and then, the reaction continued on the shaking table for 1 h; the aging process continued for 60 h at 25°C. Under these conditions, the content of the effective component, [Fe + Al]b, could reach up to 60%. The order of the removal rates of the mixed heavy metals by PPFAS is Cu(II)> Cr(III)> Pb(II)> Zn(II)> Cd(II). The order of the removal rates of the mixed complex heavy metals is EDTA‐Cd(II)> EDTA‐Zn(II)> EDTA‐Pb(II)> EDTA‐Cu(II)> EDTA‐Cr(III). © 2017 American Institute of Chemical Engineers Environ Prog, 37: 240–248, 2018

The microbial manganese removal process is believed to be the catalytic oxidation of Mn(II) by manganese oxidase. In this study, the multicopper oxidase CopA was purified and found to have high manganese oxidation activity in vitro and Cu(II) can significantly enhance its manganese oxidation activity. The gene site-directed mutagenesis was used to mutate four conserved copper binding sites of CopA and then obtain four mutant strains. The manganese removal efficiency of the four strains was determined to find that H120 is the catalytic active site of the CopA. Protein modification analysis of CopA obtained under different conditions by mass spectrometry revealed that the loss of Cu(Ⅱ) and the mutation of the conserved copper binding site H120 resulted in the loss of modification of ethoxyformyl and quinone, the number of modifications was reduced and the position of modification was changed, eventually causing a decrease in protein activity. It reveals that Cu(II) and H120 play an indispensable role in the manganese oxidation of the multicopper oxidase CopA. The Mn valence state of BioMnOx was analyzed by XPS, finding that both the strain-mediated product and the CopA-mediated product were composed of MnO2 and Mn3O4 and the average valence of Mn is 3.2.