Pb0 flue gas biosorption in denitrifying MBfR: Characteristics and binding ability of extracellular polymeric substances

Pb0 in flue gas which is ubiquitous in the environment, poses a certain threat to human and ecology, but the study on EPS-dependent stabilization of lead to remove Pb0 from flue gas remains insufficient. In this investi-gation, the characteristics and heavy metals-binding ability of four EPS fractions were evaluated. The EPS were extracted from denitrifying membrane biofilm reactor (MBfR) and divided into slime EPS (S-EPS), loosely-bound EPS (LB-EPS), tightly-bound EPS (TB-EPS) and EPS in circulating flow (Y-EPS). The S, LB, TB-EPS related to Pb stabilization on biofilm need more attention. Compared to Pb -S-EPS (0.013 mg g-1) and Pb-LB-EPS (0.13 mg g-1), the Pb-TB-EPS (0.26 mg g-1) was mainly stable form of vapor Pb0, since TB-EPS's higher content (30.67-82.44 mg g-1 VSS), proteins (13.47-36.32 mg g-1 VSS) and polysaccharides (9.37-32.48 mg g-1 VSS) concentration. Particularly, proteins related ligands were more effective in S, LB, TB-EPS dependent adsorption of Pb, complexing with hydrophobic acid ligands further strengthened in TB-EPS adsorption. The Pb-EPS com-plex formed via binding with functional groups (such as O-H, N-H, C-H and C--C) on EPS, also facilitated by loose structure of proteins. This study enlightens the researchers on the bio-treatment and EPS-dependent bio-sorption of Pb0 in flue gas in denitrifying MBfR.

Automated summary

This study evaluated the characteristics and heavy metal-binding ability of four EPS fractions extracted from denitrifying MBfR. The results showed that S, LB, and TB-EPS related to Pb stabilization on biofilm need more attention. Compared to Pb-S-EPS and Pb-LB-EPS, Pb-TB-EPS was found to be the main stable form of vapor Pb0 due to its higher content of proteins and polysaccharides. Proteins related ligands were more effective in the EPS-dependent adsorption of Pb, and the loose structure of proteins facilitated the formation of Pb-EPS complex.