Selenium (Se) Removal from Copper Refinery Wastewater Using a Combination of Zero-Valent Iron (ZVI) and Se(VI)-Reducing Bacterium, <i>Thaurea selenatis</i>

Naoko Okibe, Kiyomasa Sueishi, Mikoto Koga, Yusei Masaki, Tsuyoshi Hirajima, Keiko Sasaki, Shinichi Heguri, Satoshi Asano

Research output: Contribution to journalArticle

Abstract

The copper refinery process produces Se(VI)-bearing wastewater with a high content of Cl<sup>−</sup> and SO<sub>4</sub><sup>2−</sup> ions. To overcome the negative effect caused by Cl<sup>−</sup> and SO<sub>4</sub><sup>2−</sup> ions on Se(VI) reduction and its following removal, this study investigated the possible synergistic effect of the combination of Se(VI)-reducing bacterium, <i>Thaurea</i> (<i>T.</i>) <i>selenatis</i> and zero-valent iron (ZVI). In the presence of SO<sub>4</sub><sup>2−</sup> (200 mM) and Cl<sup>−</sup> (300 mM), the following was observed: (i) ZVI alone was unable to remove Se both under strictly aerobic and micro-aerobic conditions. (ii) Se(VI) reduction by <i>T. selenatis</i> alone was severely inhibited under anaerobic conditions (and thus no microbial growth was observed). (iii) On the other hand, <i>T. selenatis</i> was capable of growth and Se(VI) reduction under micro-aerobic conditions. (iv) Combining <i>T. selenatis</i> and ZVI under micro-aerobic conditions showed a synergistic effect on Se(VI) reduction, readily facilitating Se removal. This synergistic effect was optimized by adjusting the pH to near neutral (optimal for <i>T. selenatis</i> growth), but by adjusting the temperature to 35°C (sub-optimal for <i>T. selenatis</i> growth): Se removal of 55% by <i>T. selenatis</i> alone, was significantly improved to 98% by combining <i>T. selenatis</i> and ZVI. The proposed key process to display the synergistic effect on Se removal under micro-aerobic conditions is as follows: (i) Using the remaining dissolved O<sub>2</sub> (DO) during the first hours, <i>T. selenatis</i> can overcome the inhibitory effect of Cl<sup>−</sup> and SO<sub>4</sub><sup>2−</sup> by growing with more energy-gaining aerobic respiration, (ii) ZVI indirectly serves as a reducing agent to maintain low DO levels, consequently readily switching from aerobic to anaerobic Se(VI) respiration by <i>T. selenatis</i>. (iii) ZVI may also be acting directly for Se deposition by reducing microbially-produced intermediate Se(IV), which is more reactive than original Se(VI). The present findings could be used as a basis for developing an economically feasible and environmentally harmless bio-treatment technology for Se(VI) containing copper refinery wastewaters.
Original languageEnglish
Pages (from-to)889-894
Number of pages6
Journalmaterials transactions, jim
Volume0
Issue number0
DOIs
Publication statusPublished - 2015

Fingerprint

Metal refineries
Selenium
selenium
bacteria
Copper
Bacteria
Wastewater
Iron
iron
copper
respiration
Bearings (structural)
adjusting
Ions
Reducing Agents
Reducing agents

Cite this

Selenium (Se) Removal from Copper Refinery Wastewater Using a Combination of Zero-Valent Iron (ZVI) and Se(VI)-Reducing Bacterium, <i>Thaurea selenatis</i> / Okibe, Naoko; Sueishi, Kiyomasa; Koga, Mikoto; Masaki, Yusei; Hirajima, Tsuyoshi; Sasaki, Keiko; Heguri, Shinichi; Asano, Satoshi.

In: materials transactions, jim, Vol. 0, No. 0, 2015, p. 889-894.

Research output: Contribution to journalArticle

Okibe, Naoko ; Sueishi, Kiyomasa ; Koga, Mikoto ; Masaki, Yusei ; Hirajima, Tsuyoshi ; Sasaki, Keiko ; Heguri, Shinichi ; Asano, Satoshi. / Selenium (Se) Removal from Copper Refinery Wastewater Using a Combination of Zero-Valent Iron (ZVI) and Se(VI)-Reducing Bacterium, <i>Thaurea selenatis</i>. In: materials transactions, jim. 2015 ; Vol. 0, No. 0. pp. 889-894.
@article{17a9482d81584799b356135984fd3665,
title = "Selenium (Se) Removal from Copper Refinery Wastewater Using a Combination of Zero-Valent Iron (ZVI) and Se(VI)-Reducing Bacterium, Thaurea selenatis",
abstract = "The copper refinery process produces Se(VI)-bearing wastewater with a high content of Cl− and SO42− ions. To overcome the negative effect caused by Cl− and SO42− ions on Se(VI) reduction and its following removal, this study investigated the possible synergistic effect of the combination of Se(VI)-reducing bacterium, Thaurea (T.) selenatis and zero-valent iron (ZVI). In the presence of SO42− (200 mM) and Cl− (300 mM), the following was observed: (i) ZVI alone was unable to remove Se both under strictly aerobic and micro-aerobic conditions. (ii) Se(VI) reduction by T. selenatis alone was severely inhibited under anaerobic conditions (and thus no microbial growth was observed). (iii) On the other hand, T. selenatis was capable of growth and Se(VI) reduction under micro-aerobic conditions. (iv) Combining T. selenatis and ZVI under micro-aerobic conditions showed a synergistic effect on Se(VI) reduction, readily facilitating Se removal. This synergistic effect was optimized by adjusting the pH to near neutral (optimal for T. selenatis growth), but by adjusting the temperature to 35°C (sub-optimal for T. selenatis growth): Se removal of 55{\%} by T. selenatis alone, was significantly improved to 98{\%} by combining T. selenatis and ZVI. The proposed key process to display the synergistic effect on Se removal under micro-aerobic conditions is as follows: (i) Using the remaining dissolved O2 (DO) during the first hours, T. selenatis can overcome the inhibitory effect of Cl− and SO42− by growing with more energy-gaining aerobic respiration, (ii) ZVI indirectly serves as a reducing agent to maintain low DO levels, consequently readily switching from aerobic to anaerobic Se(VI) respiration by T. selenatis. (iii) ZVI may also be acting directly for Se deposition by reducing microbially-produced intermediate Se(IV), which is more reactive than original Se(VI). The present findings could be used as a basis for developing an economically feasible and environmentally harmless bio-treatment technology for Se(VI) containing copper refinery wastewaters.",
author = "Naoko Okibe and Kiyomasa Sueishi and Mikoto Koga and Yusei Masaki and Tsuyoshi Hirajima and Keiko Sasaki and Shinichi Heguri and Satoshi Asano",
year = "2015",
doi = "10.2320/matertrans.M2014457",
language = "English",
volume = "0",
pages = "889--894",
journal = "Materials Transactions",
issn = "0916-1821",
publisher = "The Japan Institute of Metals and Materials",
number = "0",

}

TY - JOUR

T1 - Selenium (Se) Removal from Copper Refinery Wastewater Using a Combination of Zero-Valent Iron (ZVI) and Se(VI)-Reducing Bacterium, Thaurea selenatis

AU - Okibe, Naoko

AU - Sueishi, Kiyomasa

AU - Koga, Mikoto

AU - Masaki, Yusei

AU - Hirajima, Tsuyoshi

AU - Sasaki, Keiko

AU - Heguri, Shinichi

AU - Asano, Satoshi

PY - 2015

Y1 - 2015

N2 - The copper refinery process produces Se(VI)-bearing wastewater with a high content of Cl− and SO42− ions. To overcome the negative effect caused by Cl− and SO42− ions on Se(VI) reduction and its following removal, this study investigated the possible synergistic effect of the combination of Se(VI)-reducing bacterium, Thaurea (T.) selenatis and zero-valent iron (ZVI). In the presence of SO42− (200 mM) and Cl− (300 mM), the following was observed: (i) ZVI alone was unable to remove Se both under strictly aerobic and micro-aerobic conditions. (ii) Se(VI) reduction by T. selenatis alone was severely inhibited under anaerobic conditions (and thus no microbial growth was observed). (iii) On the other hand, T. selenatis was capable of growth and Se(VI) reduction under micro-aerobic conditions. (iv) Combining T. selenatis and ZVI under micro-aerobic conditions showed a synergistic effect on Se(VI) reduction, readily facilitating Se removal. This synergistic effect was optimized by adjusting the pH to near neutral (optimal for T. selenatis growth), but by adjusting the temperature to 35°C (sub-optimal for T. selenatis growth): Se removal of 55% by T. selenatis alone, was significantly improved to 98% by combining T. selenatis and ZVI. The proposed key process to display the synergistic effect on Se removal under micro-aerobic conditions is as follows: (i) Using the remaining dissolved O2 (DO) during the first hours, T. selenatis can overcome the inhibitory effect of Cl− and SO42− by growing with more energy-gaining aerobic respiration, (ii) ZVI indirectly serves as a reducing agent to maintain low DO levels, consequently readily switching from aerobic to anaerobic Se(VI) respiration by T. selenatis. (iii) ZVI may also be acting directly for Se deposition by reducing microbially-produced intermediate Se(IV), which is more reactive than original Se(VI). The present findings could be used as a basis for developing an economically feasible and environmentally harmless bio-treatment technology for Se(VI) containing copper refinery wastewaters.

AB - The copper refinery process produces Se(VI)-bearing wastewater with a high content of Cl− and SO42− ions. To overcome the negative effect caused by Cl− and SO42− ions on Se(VI) reduction and its following removal, this study investigated the possible synergistic effect of the combination of Se(VI)-reducing bacterium, Thaurea (T.) selenatis and zero-valent iron (ZVI). In the presence of SO42− (200 mM) and Cl− (300 mM), the following was observed: (i) ZVI alone was unable to remove Se both under strictly aerobic and micro-aerobic conditions. (ii) Se(VI) reduction by T. selenatis alone was severely inhibited under anaerobic conditions (and thus no microbial growth was observed). (iii) On the other hand, T. selenatis was capable of growth and Se(VI) reduction under micro-aerobic conditions. (iv) Combining T. selenatis and ZVI under micro-aerobic conditions showed a synergistic effect on Se(VI) reduction, readily facilitating Se removal. This synergistic effect was optimized by adjusting the pH to near neutral (optimal for T. selenatis growth), but by adjusting the temperature to 35°C (sub-optimal for T. selenatis growth): Se removal of 55% by T. selenatis alone, was significantly improved to 98% by combining T. selenatis and ZVI. The proposed key process to display the synergistic effect on Se removal under micro-aerobic conditions is as follows: (i) Using the remaining dissolved O2 (DO) during the first hours, T. selenatis can overcome the inhibitory effect of Cl− and SO42− by growing with more energy-gaining aerobic respiration, (ii) ZVI indirectly serves as a reducing agent to maintain low DO levels, consequently readily switching from aerobic to anaerobic Se(VI) respiration by T. selenatis. (iii) ZVI may also be acting directly for Se deposition by reducing microbially-produced intermediate Se(IV), which is more reactive than original Se(VI). The present findings could be used as a basis for developing an economically feasible and environmentally harmless bio-treatment technology for Se(VI) containing copper refinery wastewaters.

U2 - 10.2320/matertrans.M2014457

DO - 10.2320/matertrans.M2014457

M3 - Article

VL - 0

SP - 889

EP - 894

JO - Materials Transactions

JF - Materials Transactions

SN - 0916-1821

IS - 0

ER -