Anoxic oxidation of arsenite linked to denitrification in sludges and sediments

Sun, Wenjie; Sierra, Reyes; Field, Jim A.

doi:10.1016/j.watres.2008.08.004

Cited by 44 publications

(31 citation statements)

References 35 publications

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“…Recently, several studies have demonstrated that nitrate-dependent As(III) oxidation is carried out by anaerobic microorganisms to gain energy from As(III) oxidation. As(III)-oxidizing denitrifying bacteria have been isolated from various environments including As-contaminated lakes and soil (21,25), as well as enrichment cultures (ECs), and isolates from pristine sediments and sludge samples (33,34). 16S rRNA gene clone library characterization of the ECs indicates that the predominant phylotypes were from the genus Azoarcus and the family Comamonadaceae (34).…”

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confidence: 99%

Anaerobic Oxidation of Arsenite Linked to Chlorate Reduction

Sun

Sierra-Álvarez

Milner

et al. 2010

Appl Environ Microbiol

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Microorganisms play a significant role in the speciation and mobility of arsenic in the environment. In this study, the oxidation of arsenite [As(III)] to arsenate [As(V)] linked to chlorate (ClO 3 ؊ ) reduction was shown to be catalyzed by sludge samples, enrichment cultures (ECs), and pure cultures incubated under anaerobic conditions. No activity was observed in treatments lacking inoculum or with heat-killed sludge, or in controls lacking ClO ؊ is an alternative electron acceptor to support the microbial oxidation of As(III).The contamination of drinking water with arsenic (As) is a global public health issue. Arsenic is a human carcinogenic compound (2), which poses a risk to millions of people around the world (31). The most common oxidation states of As in aqueous environments are arsenite [As(III), H 3 AsO 3 ] or arsenate [As(V), H 2 AsO 4 Ϫ , and HAsO 4 2Ϫ ]. Microbial processes play critical roles in controlling the fate and transformation of As in subsurface systems (22). As(V) binds to aluminum oxides more extensively than As(III) under circumneutral pH conditions (12, 16). Both As(III) and As(V) are strongly adsorbed on iron oxides (9). However, As(III) is more rapidly desorbed compared to As(V) (35).Aerobic bacteria can oxidize As(III) forming As(V) (14, 28), which potentially is less mobile in the subsurface environment. Also, in environments with dissolved ferrous iron [Fe(II)] the oxidation of Fe(II) (both abiotic and biotic) would result in formation of Fe(III) (hydr)oxides such as ferrihydrite which adsorb As. Oxidation processes, therefore, can decrease the mobilization of As in groundwater. However, oxygen (O 2 ) is poorly soluble in groundwater and may become consumed by microbial activity, creating anaerobic zones. Alternative oxidants aside from O 2 also have the potential to support the microbial oxidation of As(III). Recently, several studies have demonstrated that nitrate-dependent As(III) oxidation is carried out by anaerobic microorganisms to gain energy from As(III) oxidation. As(III)-oxidizing denitrifying bacteria have been isolated from various environments including As-contaminated lakes and soil (21, 25), as well as enrichment cultures (ECs), and isolates from pristine sediments and sludge samples (33, 34). 16S rRNA gene clone library characterization of the ECs indicates that the predominant phylotypes were from the genus Azoarcus and the family Comamonadaceae (34).Beside nitrate, chlorate (ClO 3 Ϫ ) can also be considered as a possible alternative oxidant for microorganisms to promote the bioremediation of contaminated plumes (6, 17). (Per)chlorate is commonly used as a terminal electron acceptor by anaerobic bacteria; as a result, it is completely degraded to the benign end product, chloride (Cl Ϫ ). Microbial reduction of perchlorate proceeds via a three-step process of ClO 4 Ϫ 3 ClO 3 Ϫ 3 ClO 2 Ϫ 3 O 2 ϩ Cl Ϫ (6). Reduction of perchlorate to chlorate, and chlorate to chlorite is catalyzed by respiratory (per)chlorate reductases (3). Subsequent disproportionation of chlorit...

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Anaerobic Oxidation of Arsenite Linked to Chlorate Reduction

Sun

Sierra-Álvarez

Milner

et al. 2010

Appl Environ Microbiol

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“…Equilibrium Equation (2.6-2.7) shows that H2AsO3 -anion is dominant in basic or slightly acidic solution whiles the HAsO3 2-dominate in basic solution (Wagman et al, 1968). The biochemistry of arsenic species has also been demonstrated by researchers (Wang et al, 2013;Sun et al, 2010;Aniruddha and Wang, 2010;Sun et al, 2008). Aniruddha and Wang, (2010) reported that As(III) can be oxidised to As(V) in the presence of oxidizing agent by donating 2 electrons, while generating a considerable amount of energy for cell growth and metabolism Equation (2.8).…”

Section: Chromium Co-pollutant (As)mentioning

confidence: 82%

“…to As(V) under both aerobic and anaerobic conditions have been investigated (Aniruddha and Wang, 2010;Sun et al, 2010;Sun et al, 2008). The first heterotrophic As(III) oxidizing bacteria was described by (Green 1918), whereas an autotrophic As(III) oxidizing strain, − 17 − Pseudomonas arsenitoxidans, was first reported in 1981 (Ilialetdinov and Abdrashitova 1981).…”

Section: Microbial Oxidation Of As(iii) To As(v)mentioning

confidence: 99%

“…The high level of these compounds in groundwater renders it unsuitable for human consumption. The removal of compounds containing Cr(VI) and As(III) involves redox processes whereby Cr(VI) is reduced to Cr(III), and oxidation of As(III) to As(V) that precipitate easily as hydroxide complexes (Aniruddha and Wang, 2010;Sun et al, 2010;Sun et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Several studies have demonstrated the effect of facultative microbes in oxidizing As(III) to As(V) using nitrate (NO3 -) or chlorate (ClO3 -) as terminal electron acceptors while conserving energy for cell growth (Sun et al, 2008;Sun et al, 2010;Aniruddha and Wang, 2010 (Cervantes et al, 2001;Suziki et al, 1992). However, the reaction is feasible since only two electrons are required for Cr(V) reduction.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic Studies of Cr(VI) Reduction in an Indigenous Mixed Culture of Bacteria in the Presence of As(III)

Tony¹,

Chirwa²

2014

proc water environ fed

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Degree:Master of Engineering (Chemical Engineering)An indigenous mixed culture of bacteria collected from a Wastewater Treatment Plant (Brits, North West Province, South Africa), biocatalytically reduced Cr(VI) in the presence of As(III). Both the reduced chromium (Cr(III)) and the oxidised arsenic (As(V)) readily form amorphous hydroxides that can be easily separated or precipitated from the aqueous phase as part of the treatment process. Treatment of Cr(VI) and As(III) before disposal of wastewater is critical since both compounds are known to be carcinogenic and mutagenic at very low concentrations, and acutely toxic at high concentrations.Batch experiments were conducted to evaluate the rate of Cr(VI) reduction under anaerobic condition in the presence of its co-contaminant As(III) typically found in the groundwater and mining effluent. Results showed near complete Cr(VI) reduction under initial Cr(VI) concentrations up to 70 mg/L in a batch amended with 20 mg/L As(III). However, increasingCr(VI) concentrations up to 100 mg/L resulted in the inhibition of Cr(VI) reduction activity.Further investigation was conducted in a batch reactor amended with 70 mg/L Cr(VI) concentration at different As(III) concentrations ranging from 5-70 mg/L to evaluate the effect of varying As(III) concentration on Cr(VI) reduction efficiency. Results showed that Cr(VI) reduction efficiency increased as As(III) concentrations increased from 5-40 mg/L.However, further increase in As(III) concentration up to 50 mg/L resulted in incomplete Cr(VI) reduction and decrease in Cr(VI) reduction efficiency. These results suggest that the rate of Cr(VI) reduction depends on the redox reaction of As(III) and As(V) with Cr(VI).Moreover, the inhibitory effect observed at high Cr(VI) and As(III) concentration may also − ii − be attributed to the dual toxicity effect of Cr(VI) and As(III) on microbial cell. From the above batch kinetic studies lethal concentration of Cr(VI) and As(III) for these strains was evaluated and established.Initial evaluation of the bacteria using 16S rRNA partial sequence method showed that cells in the mixed culture comprised predominantly of the Gram-positive species: Staphylococcus sp., Enterobacter sp., and Bacillus sp. The biokinetic parameters of these strains were estimated using a non-competitive inhibition model with a computer programme for simulation of the Aquatic System "AQUASIM 2.0". Cr(VI) reduction efficiency along the longitudinal column was also evaluated in this study.Results showed that Cr(VI) efficiency increased as Cr(VI) concentration travels along the longitudinal column. Other important factors such as oxygen and pH during biological Cr(VI) reduction in the presence of As(III) oxidation were also evaluated.

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Anoxic oxidation of arsenite linked to chemolithotrophic denitrification in continuous bioreactors

Sun

Sierra-Álvarez

Hsu

et al. 2010

Biotech & Bioengineering

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In this study, the anoxic oxidation of arsenite (As(III)) linked to chemolithotrophic denitrification was shown to be feasible in continuous bioreactors. Biological oxidation of As(III) was stable over prolonged periods of operation ranging up to 3 years in continuous denitrifying bioreactors with granular biofilms. As(III) was removed with a high conversion efficiency (> 92%) to arsenate (As(V)) in periods with high volumetric loadings (e.g. 3.5 to 5.1 mmol As Lreactor−1 d−1). The maximum specific activity of sampled granular sludge from the bioreactors was 0.98±0.04 mmol As(V) formed g−1 VSS d−1 when determined at an initial concentration of 0.5 mM As(III). The microbial population adapted to high influent concentrations of As(III) up to 5.2 mM. However, the As(III) oxidation process was severely inhibited when 7.6 to 8.1 mM As(III) was fed. Activity was restored upon lowering the As(III) concentration to 3.8 mM. Several experimental strategies were utilized to demonstrate a dependence of the nitrate removal on As(III) oxidation as well as a dependence of the As(III) removal on nitrate reduction. The molar stoichiometric ratio of As(V) formed to nitrate removed (corrected for endogenous denitrification) in the bioreactors approximated 2.5, indicating complete denitrification was occurring. As(III) oxidation was also shown to be linked to the complete denitrification of NO3− to N2 gas by demonstrating a significantly enhanced production of N2 beyond the background endogenous production in a batch bioassay spiked with 3.5 mM As(III). The N2 production also corresponded closely to the expected stoichiometry of 2.5 mol As(III) mol−1 N2-N for complete denitrification.

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Anoxic oxidation of arsenite linked to denitrification in sludges and sediments

Cited by 44 publications

References 35 publications

Anaerobic Oxidation of Arsenite Linked to Chlorate Reduction

Anaerobic Oxidation of Arsenite Linked to Chlorate Reduction

Kinetic Studies of Cr(VI) Reduction in an Indigenous Mixed Culture of Bacteria in the Presence of As(III)

Anoxic oxidation of arsenite linked to chemolithotrophic denitrification in continuous bioreactors

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