Flue gas arsenic trioxide removal from sludge incineration by sulfate-reducing membrane biofilm reactor

Abstract

Arsenic in flue gas from sludge incineration may damage to human health and ecological environment seriously. The sulfate-reducing membrane biofilm reactor (SRBR) was investigated for arsenic trioxide(As2O3) removal in flue gas from sludge incineration. Arsenic removal efficiency attained 94.4%. Desulfovibrio, UC_Clostridiales, and Pseudodesulfovibrio were the dominant genera. Desulfovibrio was the core arsenite-oxidizing-sulfate-reducing genus. Arsenite oxidase (ArxA) and sulfate-reducing enzymes (Sat, AprAB and DsrAB) responsible for bacterial As(III)-oxidation and sulfate reduction. Desulfovibrio could synthetically regulate the expression of functional proteins that involved in As oxidation, sulfate reduction, cell wall and membrane synthesis, antioxidant, DNA repair, glycolysis and amino acid synthesis under As stress, possessed resistant and removal ability to As. The biofilm in SRBR was characterized by FTIR, XPS, XRD, EEM, and SEM-EDS. XPS and XRD spectra indicate the formation of an arsenic species (As(V)) from arsenic oxidation. Humic acid complex arsenic (HA-As) and arsenopyrite-like phase (Fe-As-S) precipitation were formed in SRBR. Microbial arsenic oxidation was coupled sulfate reduction and biostabilization of arsenic from flue gas. Arsenic in flue gas was bio-stabilized in the form of Fe-As-S and HA-As via biocomplexation of humic acids in extracellular polymeric substances (EPS), biosorption and biodeposition. These results show that the sulfate-reducing membrane biofilm reactor is achievable and open new possibilities for applying the SRBR to removal of arsenic in flue gas from sludge incineration.