Microbial transformation of arsenic K. Fukushi 1 , T. Hashimoto 2 , - - PowerPoint PPT Presentation

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Microbial transformation of arsenic K. Fukushi 1 , T. Hashimoto 2 , - - PowerPoint PPT Presentation

Jan 19, 2023 561 likes •874 views

1 Microbial transformation of arsenic K. Fukushi 1 , T. Hashimoto 2 , S. M. A. Islam 3 , and K. M. Hassan 2 1 Integrated Research System for Sustainability Science (IR3S), The University of Tokyo 2 Department of Urban Engineering, The University

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Microbial transformation of arsenic

  • K. Fukushi1, T. Hashimoto2, S. M. A. Islam3, and K. M. Hassan2

1 Integrated Research System for Sustainability Science (IR3S), The

University of Tokyo

2 Department of Urban Engineering, The University of Tokyo 3 Department of Civil Engineering, Dhaka University of Engineering

and Technology (DUET)

Asian Science and Technology Seminar (ASTS) in Thailand, March 10-11, 2008

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Background and Introduction

Arsenic leaching problem from mine tailings Arsenic contamination from natural aquifers

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Arsenic contamination of soil

Continued cropping with arsenic

contaminated irrigation water increases the extent of contamination in agricultural land

A large amount of arsenic as high as 10

kg/ha per year is cycled through irrigated water in Bangladesh (DPHE/BGS 2000)

Some recent studies observed

considerable arsenic concentration in rice and vegetables grown on arsenic

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Irrigating As contaminated groundwater by electrical pump

2003 September, Photo taken by Ken Fukushi

Bangladesh

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Red: Contam inated Green: Not contam inated ( Bangladesh)

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Arsenic Iron Removal Process (AIRP)

2003 September, Photo taken by K. Fukushi

Bangladesh

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Relationship between arsenic

  • concs. in soil and groundwater

10 20 30 40 50 60 70 80 90 0.2 0.4 0.6 0.8 1

Water arsenic concentration( mg/kg)

Soil arsenic concentration (mg/kg) Huq et al [14] Islam et al [18]

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Arsenic from mine tailing

2000 October, Photo taken by Ken Fukushi

Thailand

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ヒ 素汚染地域遠景 ヒ 素汚染表層水 ヒ 素汚染表層水 ヒ 素汚染河川水

Thailand

Polluted area Polluted surface water Polluted surface water Polluted surface water

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Transformation of arsenic in natural environment

Sediment Arsenate Arsenite Dimethylarsenic Acid (DMAA) Methylarsenic Acid (MMAA) OH CH3 Arsenite Arsenate Arsine MMA Methylarsine CH3 Trimethylarsine

  • xide (TMAO)

DMAA Trimethylarsine (TMA) Dimethylarsine (DMA) Rain Bacteria Bacteria Bacteria Bacteria Arsenite

Air Water Soil

Sediment Arsenate Dimethylarsenic Methylarsenic OH CH Arsenate Arsine MMA Methylarsine CH Trimethylarsine DMAA (TMA) Dimethylarsine (DMA) Rain Bacteria Bacteria Bacteria Bacteria Arsenite

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Bio-Methylation-mechanism

Proposed for C. humicola

Arsenate Arsenite Methyl arsonate Methyl arsonite Dimethyl arsinite Trimethyl arsine oxide Trimethyl arsine

reduction

Arsenate Dimethyl arsinate Arsenite Methyl arsonate Methyl arsonite

reduction methylation reduction methylation methylation reduction

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As(V)-As(III) reduction

Bio-Methylation

Glutathione (GSH) provides the electrons for reduction and probably methylcobalamin is the methyl donor for anaerobic microorganisms

reduction methylation

R1 = R2 = OH, arsenate; R1 = CH3, R2 = OH, methylarsonate; R1 = R2 = CH3, dimethylarsinate

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APPLICATION FOR CLEANUP

High efficiency of methylation

Up to 100 times comparing over the natural

condition by mixed culture

Up to 1000 times comparing over the natural

condition by pure culture1313

Application examples

Soil Sludge from water treatment Other solids containing arsenic

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Arsenic Iron Removal Process (AIRP)

2003 September, Photo taken by K. Fukushi

Bangladesh

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Arsenic removal technology

Arsenic Iron Removal

Plant: AIRP

Arsenic in groundwater

is complexed with ferric hydroxide and removed with sand filter

diagram

As sludge

Need proper disposal

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16 ARSENIC VOLATILIZATION

MMA B.P.: 2℃ DMA B.P.: 36℃ TMA B.P.: 52℃

To be dispersed

As(III) As(V) 16 4.5 1000 1800 8000

LD50 (mg/ kg)

１ 3.6 0.016 0.009 0.002

Relative Toxicity

Purification process

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Volatilization

dispersion

Rain Ocean

As As As As As As As As

Arsenic polluted soil

Microbial transform

Rain

High toxicity (solid/liquid)

Soil remediation

Low toxicity (gas)

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20 40 60 80 100 120 140 0.0 0.4 0.8 1.2 1.6 2.0 2.4

Cumulative time (Days) MMA production rate (µgAs/d)

0.0 0.4 0.8 1.2 1.6 2.0

% of total arsenic converted in gas

Arsenic gasification rate in soil column

after augmentation before augmentation

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NATURAL EMISSION OF GASEOUS ARSENIC

In order to promote arsenic methylation

technology for environmental clean-up, we need to know natural arsenic emission level from earth.

Natural emission of gaseous arsenic from

earth is biologically conducted.

Fate of gasified As should be investigated

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By K. Yoshimura

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Arsenic cycle on earth (conceptual)

As III/As V Methylated arsine (TMA)

* *

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Biological liquefaction of arsenic

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Conceptual Arsenic Leaching Mechanism in Groundwater in Response to Organic Matter

Solid Bound As(V) Solid Bound As(V)

Aerobic Biofilm

Solid Bound As(V)

Anaerobic Biofilm Aqueous As(V,III) Shallow Tube W ell Deep Tube W ell

Solid Bound As(V)

As Contaminated Water As Free Water Organic Contamination Buried Organic Sediments I ndustrial + Agriculture + Household W astew ater

Fe( OH) 3 As As As As As As Fe( OH) 3 NOM As NOM As As As

NOM

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Arsenic Leaching: AIRP Perspective

Instantaneous chemical leaching of arsenic: Competitive binary adsorption

As OM As OM Fe( OH) 3 As OM As OM As As As Fe( OH) 3 OM As OM As As As OM OM As As As

Sludge Gravel Treated Water Sand Filter

Sand Gravel Pea-Gravel

Fe( OH) 3 OM As OM As As As As As Aerobic Biofilm As As Fe( OH) 3 OM As OM As As As Anaerobic Biofilm

Bioleaching of arsenic from the accumulated sludge in AIRP filter bed

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Biotransformation of arsenic

Gasification by arsenic methylating bacteira

(AsMB)

Liquefaction by anoxic organisms Other biological oxidation/deduction of arsenic Understanding of natural system of the

country/region

Strategy for the adaptation

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Thanking you

Ken Fukushi fukushi@ir3s.u-tokyo.ac.jp

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Bangladesh

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Latest statistics on arsenic conc in groundwater of Bangladesh

1.67 Maximum arsenic concentration observed in tested samples (mg/l) 0.0108 Median value of arsenic concentration observed in tested samples (mg/l) 85 (66%) Total population where arsenic concentration exceeds 0.05 mg/l (million) 89,186 (60%) Total area where arsenic concentration exceeds 0.05 mg/l (km2) 41/60 Total number of districts where arsenic concentration exceeds 0.05 mg/l 52/60 Total number of districts where arsenic concentration exceeds 0.01 mg/l 60 Total number of districts surveyed 64 Total number of administrative districts 128 Total population (million) 147,570 Total area in Bangladesh (km2)

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Arsenic concentration in agriculture soil in Bangladesh

* Depth of soil 0-50 cm

Location Arsenic concentration (mg/kg) (3) 9.8±0.7 (3) 3.9±0.4 (3) 40.4±2.1 (2) 7.0±0.7 (2) 3.9±0.5 (2) 80.9±4.2 (1) 46.5±2.4 (1) 12.3±1.1 (1) 55.6±3.2 (1) 60.1±3.7

Dhaka

Bangladesh

India India India Myanmar Bay of Bengal Sample Locations (1) Manikgonj (2) Munshigonj (3) Comilla (1) (2) (3)