Bio-transformation and stabilization of arsenic (As) in contaminated soil using arsenic oxidizing bacteria and FeCl3 amendment

Abstract

A combination of biological and chemical methods was applied in the present study to evaluate the removal of arsenic (As) from contaminated soil. The treatment involved As-oxidizing microbes aimed of transforming the more toxic As (III) to less toxic As (V) in the soil. FeCl 3 was added at three different concentrations (1, 2, and 3%) to stabilize the As (V). Leaching of the treated soil was investigated by making a soil column and passing tap water through it to determine solubility. Experimental results indicated that the bacterial activity had a pronounced positive effect on the transformation of As, and decreased the soluble exchangeable fraction from 50 to 0.7 mg/kg as compared to control and from 50 to 44 mg/kg after 7 days of treatment. FeCl 3 also played an indispensable role in the adsorption/stabilization of As in the soil; 1 and 2% FeCl 3 strongly influenced the adsorption of As (V). The soil leachate contained negligible amount of As and trace metals, which indicates that combining an efficient microbe with a chemical treatment is very effective route for the removal and stabilization of As from contaminated soil in the environment.

Microbial Oxidation of Arsenite: Regulation, Chemotaxis, Phosphate Metabolism and Energy Generation

“…and As(III)-oxidizing microorganisms are used as biological reagents in combination with iron for the treatment of arsenic contamination (Karn et al, 2017;Yang et al, 2017). The combination of an As(III)-oxidizing bacterium Brevibacterium sp.…”

“…YZ-1 and biogenic schwertmannite could immobilize arsenic in the highly arsenic contaminated soil (Yang et al, 2017). Combining an As(III)-oxidizing bacterium XS4 with FeCl 3 also significantly stabilized arsenic in soil (Karn et al, 2017). Simultaneous removal of As(III) and was achieved by the immobilized Enterobacter strain in combination with FeCl 3 and Ca(OH) 2 (Shi et al, 2020).…”

“…Microorganisms promote the interaction of arsenic and iron. In nature, the presence, enrichment and migration of arsenic is often associated with iron-containing minerals and As(III)-oxidizing microorganisms are used as biological reagents in combination with iron for the treatment of arsenic contamination ( Karn et al, 2017 ; Yang et al, 2017 ). The combination of an As(III)-oxidizing bacterium Brevibacterium sp.…”

Specifically Designed Magnetic Biochar From Waste Wood for Arsenic Removal

“…The purpose of separating arsenic pollutants and water was achieved through filtration [4]. Karn et al (2017) used FeCl 3 as flocculants to remove arsenite and the efficiency reached 77%. The removal efficiency did not increase obviously, when the dosage of FeCl 3 continued to increase [5].…”

Simultaneous 3-/4-Hydroxybenzoates Biodegradation and Arsenite Oxidation by Hydrogenophaga sp. H7

“…In nature, the dominant forms of As are arsenite [As(III)] and arsenate [As(V)]; As(III) is more toxic and mobile than As(V) (Smedley et al, 2002; Karn and Pan, 2017a). Because of the different characteristics of As(III) and As(V), As removal technology generally utilizes a two-step method that involves the oxidation of As(III) followed by the adsorption of As(V) (Nicomel et al, 2015; Karn et al, 2017b; Luong et al, 2018). Microorganisms are the principal drivers of As(III) oxidation by As(III) oxidase AioAB in nature (Cai et al, 2009; Liu et al, 2012).…”