Laboratory of Agro-Waste to Resource/Scientific Observing and Experimental Station of Dali, Institute of Agro-environmental Protection, Ministry of Agriculture, Tianjin 300191, PR China Key Laboratory of Production Environment and Agro-product Safety, Ministry of Agriculture, Tianjin 300191, PR China Tianjin Key Laboratory of Agro-environment and Agro-product Safety, Tianjin 300191, PR China

Abstract:
Hydrogenotrophic bacteria (HTB) were introduced into a nitrate removal system, which used nanoscale zero-valent iron (nZVI) as reductant, to investigate its bioinhibitory effect. Based on the results, it was noted that addition of HTB culture (10–50 mL) led to 58.9–91.4% decrease in the first observed rate constant (kobs1), which represented the nitrate removal rate by nZVI, and a reduction in the generated poisonous by-products from 94.9% to 38.5%. In other words, HTB had a significant inhibitory effect on nitrate reduction by nZVI. However, the pathway of this bioinhibition only prevented the occurrence of chemical reduction, but not competition for nitrate. Furthermore, FeOOH coating was observed on the surface of nZVI, instead of Fe3O4or Fe2O3, which could prevent electron transmission from nZVI to nitrate. Considering that FeOOH was the product of iron corrosion, the result indicated that HTB could inhibit chemical reduction by enhancing the reaction between nZVI and water.

Keywords:    Heart failure    Collagen    Cross-linked amino acid    Mass spectrometry    Precursor ion scan    Hydrogenotrophic bacteria    Nanoscale zero-valent iron    Nitrate removal    Bioinhibitory effect    Iron corrosion