Autotrophic denitrification by nitrate-dependent Fe(II) oxidation in a continuous up-flow biofilter
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A continuous-upflow biofilter packed with sponge iron was constructed for nitrate removal under an anaerobic atmosphere. Microbacterium sp. W5, a nitrate reducing and Fe(II) oxidizing strain, was added to the biofilter as an inoculum. The best results were achieved when NO3 −-N concentration was 30 mg/L and Fe2+ was 800 mg/L. Nitrite in influent would inhibit nitrate removal and aqueous Fe2+ resulted in encrustation. Fe(II)EDTA would prevent cells from encrustation and the maximum nitrogen removal efficiency was about 90 % with Fe(II)EDTA level of 1100 mg/L. Nitrate reduction followed first-order reaction kinetics. Characteristics of biofilms were analyzed by X-ray fluorescence spectroscopy.
KeywordsContinuous-upflow biofilter Encrustation Nitrate-dependent Fe(II) oxidation Nitrate removal
This work was financially supported by the National Natural Science Foundation of China (NSFC) (No. 51008239 and 51378400), the Natural Science Foundation of Hubei Province, China (No. 2013CFB289 and 2013CFB308) and, the National "Twelfth Five-Year" Plan for Science and Technology Pillar Program (2014BAL04B04, 2015BAL01B02).
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