Arsenic and nitrate remediation by isolated FeOB strains coupled with additional ferrous iron in the iron-deficient...

Remediation of As(III) by use of Fe(II) oxidation bacteria (FeOB) in iron-rich soils has been reported, but seldom used in the iron-deficient soil of arid areas. This study was aimed at selecting native bacterial strains to remediate As pollution in arid soils, coupled with the addition of Fe(II). The used methods included: The selection of two FeOB strains; XRD for solid phase identification based on peaks; SEM with EDS for morphology identification of newly formed minerals with chemical compositions; XPS for surface chemistry of the minerals; FTIR for functional groups of precipitates and 3DEEM for EPS determination, etc. The results were as follows: Sharp decrement curves of As(III) and NO₃^- with Fe(II) and total Fe contents and increment of NO₂^-; NH₄⁺ fluctuating during the experimental period of 11 days; and precipitation of Fe(III) hydroxides together with As(III) with broken FeOBs due to encrustation in the SEM scan. It was concluded that two selected Pseudomonas strains have NAFO functionality by addition of iron as iron reduction-oxidation pair in the arid soil, further potentially fixing NH₄⁺ while As(III) can be effectively remediated through the FeOB participation in forms of adsorption and co-precipitation of Fe(OH)₃ through an oxidation of Fe(II) process.