Long-term electrode behavior during treatment of arsenic contaminated groundwater by a pilot-scale iron electrocoagulation system

Bandaru, Siva R. S.; Roy, Abhisek; Gadgil, Ashok J.; van Genuchten, Case M.

doi:10.1016/j.watres.2020.115668

Title: Long-term electrode behavior during treatment of arsenic contaminated groundwater by a pilot-scale iron electrocoagulation system

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Abstract

Iron electrocoagulation (Fe-EC) is an effective technology to remove arsenic (As) from groundwater used for drinking. A commonly noted limitation of Fe-EC is fouling or passivation of electrode surfaces via rust accumulation over long-term use. In this study, we examined the effect of removing electrode surface layers on the performance of a large-scale (10,000 L/d capacity) Fe-EC plant in West Bengal, India. We also characterized the layers formed on the electrodes in active use for over 2 years at this plant. The electrode surfaces developed three distinct horizontal sections of layers that consisted of different minerals: calcite, Fe(III) precipitates and magnetite near the top, magnetite in the middle, and Fe(III) precipitates and magnetite near the bottom. The interior of all surface layers adjacent to the Fe(0) metal was dominated by magnetite. We determined the impact of surface layer removal by mechanical abrasion on Fe-EC performance by measuring solution composition (As, Fe, P, Si, Mn, Ca, pH, DO) and electrochemical parameters (total cell voltage and electrode interface potentials) during electrolysis. After electrode cleaning, the Fe concentration in the bulk solution increased substantially from 15.2 to 41.5 mg/L. This higher Fe concentration led to increased removal of a number of solutes. Formore »« less

Authors:: Bandaru, Siva R. S.; Roy, Abhisek; Gadgil, Ashok J.; van Genuchten, Case M.

Publication Date:: Fri May 01 00:00:00 EDT 2020

Research Org.:: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:: 1603717

Alternate Identifier(s):: OSTI ID: 1603643

Grant/Contract Number:: AC02-76SF00515; AC02-05CH11231

Resource Type:: Published Article

Journal Name:: Water Research

Additional Journal Information:: Journal Name: Water Research Journal Volume: 175 Journal Issue: C; Journal ID: ISSN 0043-1354

Publisher:: Elsevier

Country of Publication:: United Kingdom

Language:: English

Subject:: 42 ENGINEERING; 58 GEOSCIENCES; anodic dissolution; electrode surface layers; iron electrocoagulation; arsenic removal; sustainable water treatment

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                    Bandaru, Siva R. S., Roy, Abhisek, Gadgil, Ashok J., and van Genuchten, Case M. Long-term electrode behavior during treatment of arsenic contaminated groundwater by a pilot-scale iron electrocoagulation system.  United Kingdom: N. p., 2020. 
Web.  doi:10.1016/j.watres.2020.115668.

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                    Bandaru, Siva R. S., Roy, Abhisek, Gadgil, Ashok J., & van Genuchten, Case M. Long-term electrode behavior during treatment of arsenic contaminated groundwater by a pilot-scale iron electrocoagulation system.  United Kingdom.  https://doi.org/10.1016/j.watres.2020.115668

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                    Bandaru, Siva R. S., Roy, Abhisek, Gadgil, Ashok J., and van Genuchten, Case M. Fri .  
"Long-term electrode behavior during treatment of arsenic contaminated groundwater by a pilot-scale iron electrocoagulation system".  United Kingdom.  https://doi.org/10.1016/j.watres.2020.115668.

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@article{osti_1603717,

  title        = {Long-term electrode behavior during treatment of arsenic contaminated groundwater by a pilot-scale iron electrocoagulation system},

  author       = {Bandaru, Siva R. S. and Roy, Abhisek and Gadgil, Ashok J. and van Genuchten, Case M.},

  abstractNote = {Iron electrocoagulation (Fe-EC) is an effective technology to remove arsenic (As) from groundwater used for drinking. A commonly noted limitation of Fe-EC is fouling or passivation of electrode surfaces via rust accumulation over long-term use. In this study, we examined the effect of removing electrode surface layers on the performance of a large-scale (10,000 L/d capacity) Fe-EC plant in West Bengal, India. We also characterized the layers formed on the electrodes in active use for over 2 years at this plant. The electrode surfaces developed three distinct horizontal sections of layers that consisted of different minerals: calcite, Fe(III) precipitates and magnetite near the top, magnetite in the middle, and Fe(III) precipitates and magnetite near the bottom. The interior of all surface layers adjacent to the Fe(0) metal was dominated by magnetite. We determined the impact of surface layer removal by mechanical abrasion on Fe-EC performance by measuring solution composition (As, Fe, P, Si, Mn, Ca, pH, DO) and electrochemical parameters (total cell voltage and electrode interface potentials) during electrolysis. After electrode cleaning, the Fe concentration in the bulk solution increased substantially from 15.2 to 41.5 mg/L. This higher Fe concentration led to increased removal of a number of solutes. For As, the concentration reached below the 10 μg/L WHO MCL more rapidly and with less total Fe consumed (i.e. less electrical energy) after cleaning (128.4 μg/L As removed per kWh) compared to before cleaning (72.9 μg/L As removed per kWh). Similarly, the removal of P and Si improved after cleaning by 0.3 mg/L/kWh and 1.1 mg/L/kWh, respectively. Our results show that mechanically removing the surface layers that accumulate on electrodes over extended periods of Fe-EC operation can restore Fe-EC system efficiency (concentration of solute removed/kWh delivered). Since Fe release into the bulk solution substantially increased upon electrode cleaning, our results also suggest that routine electrode maintenance can ensure robust and reliable Fe-EC performance over year-long timescales.},

  doi          = {10.1016/j.watres.2020.115668},

  journal      = {Water Research},

  number       = C,

  volume       = 175,

  place        = {United Kingdom},

  year         = {Fri May 01 00:00:00 EDT 2020},

  month        = {Fri May 01 00:00:00 EDT 2020}

}

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