Microbiological synthesis of denitrifying bacteria-iron nanopartical composite material and its eminent performance in removal of nitrate-N

Abstract Denitrifying bacteria-Iron nanoparticles (FeNPs) composite material was biosynthesized to get rid of Nitrate-N. FeNPs were synthesized by the biological reducing capacity of denitrifying bacteria without additional chemical reagent. And then they were loaded in the denitrifying bacteria to fabricate composite material which were characterized by UV–Vis spectra, XPS, FTIR and TEM confirming the FeNPs are embedded in the bacteria and fully protected by the bacteria. The composite material can remove nearly 100% nitrate–N in 420 min without more ammonia-N generation. FeNPs loaded in the Denitrifying bacteria-FeNPs composite material can act as the electron donor for denitrifying bacteria to complete the biological denitrification process which will accelerate denitrification rate without releasing additional Ammonia-N. The denitrifying bacteria can protect FeNPs from being oxidized in the environment and from reacting with nitrate-N to produce ammonia-N. FeNPs recovering process and denitrification process are in progress at the same time since denitrifying bacterium can synthesize FeNPs by recovering Fe2+ and Fe3+ in the system at all times.