KSBB Journal

The Korean Society for Biotechnology and Bioengineering (한국생물공학회)
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Effects of pH Control Methods on Removal Efficiency in Electrokinetic Bioremediation of Phenanthrene-contaminated Soil

Phenanthrene-오염토양의 동전기 생물학적 복원에서 pH 조절방법이 제거효율에 미치는 영향

  • Kim, Sang-Joon (The Korean Intellectual Property Office) ;
  • Park, Ji-Yeon (Korea Institute of Energy Research) ;
  • Lee, You-Jin (Department of Chemical and Biomolecular Engineering, KAIST) ;
  • Yang, Ji-Won (Department of Chemical and Biomolecular Engineering, KAIST)
  • Published : 2006.06.28
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Abstract

In this study, problems related with pH control in electrokinetic(EK) bioremediation of phenanthrene contaminated soil were observed, and the effects of pH control methods on the removal efficiency were investigated to search a further application strategy. In a preliminary experiment, it was found out by flask cultivation that a certain sulfate concentration was needed to degrade phenanthrene well using Sphingomonas sp. 3Y. However, when $MgSO_4$ was used as sulfate source in EK bioremediation, the bacterial activity reduced seriously due to the abrupt decrease of pHs in soil and bioreactor by the combination of magnesium and hydroxyl ions. When another strong buffering compound was used to control the pH problem, the good maintenance of the bacterial activity and pHs could be observed, but the removal efficiency decreased largely. When a low concentration of $MgSO_4$ was added, the removal efficiency decreased somewhat in spite of the good maintenance of neutral pHs. With the addition of NaOH as a neutralizing agent, the removal efficiency also decreased because of the increase of soil pH. Consequently the selection of electrolyte composition was a very important factor in EK bioremediation and some sulfate sources suitable for both bacterial activity and contaminant degradation should be investigated.

본 연구에서는 phenanthrene-오염토양의 정화를 위한 동전기 생물학적복원에서 나타나는 pH 조절과 관련한 문제점과 이것에 대한 해결방법이 복원효과에 어떠한 영향을 주는지 조사하므로써 앞으로의 방향을 모색하고자 하였다. 플라스크 배양실험에서 Sphingomonas sp. 3Y를 이용하여 phenanthrene를 분해하기 위해서는 황산염을 적절한 농도로 공급하는 것이 중요하였는데 동전기 생물학적복원에서는 $MgSO_4$를 황산염원으로 공급했을 때 Mg이온이 음극에서 생성된 수산화이온과 결합하여 침전물을 형성하고 토양과 생물반응기의 pH를 과도하게 감소시키므로 미생물활성을 저해하고 제거효율이 감소되었다. 따라서 pH를 중성으로 유지하기 위해 강한 완충성분을 사용한 경우 비록 pH와 미생물활성은 잘 유지되었지만 제거효율이 크게 감소되었다. 한편 낮은 농도로 $MgSO_4$를 공급했을 때 역시 pH와 미생물활성은 잘 유지하였으나 제거효율이 다소 감소하였다. NaOH와 같은 중화제를 첨가한 경우에는 토양 pH의 상승하여 제거효율이 감소되었다. 결과적으로 전해질 조성은 동전기 생물학적복원의 복원효율에 매우 중요한 요소이며 앞으로 오염물 분해와 미생물활성유지에 적합한 황산염원이 조사되어야 한다.

Keywords

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