Journal of Korean Society of Environmental Engineers (대한환경공학회지)

Korean Society of Environmental Engineers (대한환경공학회)
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Treatment of Fluoride in Semiconductor Wastewater by using Fluidized Bed Reactor

유동상 반응기를 이용한 반도체 폐수의 불소 처리

  • An, Myeong-Ki (Department of Environmental Engineering, Chungbuk National University) ;
  • Kim, Keum-Yong (Department of Environmental Engineering, Chungbuk National University) ;
  • Ryu, Hong-Duck (Department of Environmental Engineering, Chungbuk National University) ;
  • Lee, Sang-Ill (Department of Environmental Engineering, Chungbuk National University)
  • Received : 2010.02.03
  • Accepted : 2010.04.27
  • Published : 2010.05.31
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Abstract

This work was initiated both to maximize purity of calcium fluoride sludge and to minimize water content in the settled sludge. The sludge was produced in the process of fluoride removal of semiconductor wastewater by the addition of $Ca^{2+}$ ion. Fludized bed reactor(FBR) using calcium fluoride as a seed was adapted. Optimum pH and molar ratio of $Ca^{2+}/F^-$ were determined in lab-scale study. The experimental results showed that fluoride removal was increased as pH and molar ratio of $Ca^{2+}/F^-$ increased, with the best removal of 79.8% in an optimum condition. In the optimum point of fluoride removal, very low ${PO_4}^{3-}$-P removal of 9.3% was observed. It indicates forming $CaF_2$ crystal of high purity, when side reaction of calcium with phosphate was minimized. In addition, water content of settled sludge was 19.3%, which is relatively low compared to other fluoride removal processes. Consequently, the FBR process proposed in this study was very effective in fluoride removal, producing good sludge of high purity and less water content.

본 연구에서는 반도체 폐수에 함유된 불소 처리 시 유동상 반응기 (FBR)을 이용하여 불소 제거 효율을 극대화 시키는 조건에서 발생하는 슬러지의 함수율을 최소화 시키고 $CaF_2$의 순도를 높이고자 하였다. 이를 위해 최적 pH 및 $Ca^{2+}$ 주입몰 비 ($[Ca^{2+}]/[F^-]$)가 도출되었다. 연구 결과 pH 및 $Ca^{2+}$ 주입 몰비가 증가함에 따라 불소 제거효율은 증가하였으며, 최적조건에서 79.8%의 불소제거효율이 관찰되었다. 불소 제거 효율이 최적인 조건에서 인 제거 효율은 약 9.3% 로서 불소 제거시 $Ca^{2+}$과 ${PO_4}^{3-}$-P의 부 반응이 거의 발생하지 않아 높은 순도의 $CaF_2$이 침전 슬러지로 발생하는 것으로 나타났다. 또한 이때 슬러지 함수율은 약 19.3%로 매우 낮은 것으로 나타나 불소 제거, 슬러지 순도 및 함수율 측면에서 FBR은 매우 효과적인 불소 제거 공정인 것으로 나타났다.

Keywords

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