Journal of Korean Society of Environmental Engineers (대한환경공학회지)

Korean Society of Environmental Engineers (대한환경공학회)
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Effect of pH Control, Ozonation and Coagulation on THMs Formation in Dringking Water Treatment Process of the Downstream of Nakdong River

낙동강 하류의 정수처리 공정에서 pH, 오존 및 응집이 트리할로메탄 생성에 미치는 영향

  • 이정규 (부산시 상수도사업본부 수질연구소) ;
  • 손희종 (부산시 상수도사업본부 수질연구소) ;
  • 김상구 (부산시 상수도사업본부 수질연구소) ;
  • 황영도 (부산시 상수도사업본부 수질연구소) ;
  • 류동춘 (부산시 상수도사업본부 수질연구소)
  • Received : 2017.01.19
  • Accepted : 2017.02.24
  • Published : 2017.03.31
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Abstract

This study was conducted to evaluate the effects of pH control and ozonation, coagulation on trihalomethanes (THMs) formation during prechlorination of the Nakdong river water. The results showed that lower pH was reduced THMs formation during prechlorination. THMs formation of water lowered pH 9.5 to 9.0, was reduced 18.3% and lowered pH 9.0 to 8.0 was reduced 14%, lowered pH 8.0 to 7.0 was reduced 7%, lowered pH 9.5 to 8.0 was reduced 29%. A low ozone dose ($0.11{\sim}0.48mg{\cdot}O_3/DOC$) before chlorination reduced the yields of THMs (reduced 6~24% in chlorination) compared with no preozonation. Thus the low ozone dose pretreatment is relatively effective plan to reduce THMs formation during chlorination. When ozone 1.0 mg/L, Alum 40 mg/L and sulfuric acid 6 mg/L dosed, The yields of THMs formation was reduced 42% compared with only chlorination. Input of chlorine after preozonation (followed coagulation, pH control) is more effective than only decline pH at a intake station to control THMs formation in a water treatment process. When chlorine 2.5 mg/L was added before coagulation (alum 40 mg/L), THMs formation was reduced 19% by lower pH and decreased 18% by a natural organic matter (NOM) removal compared with only chlorine 2.5 mg/L addition. Because coagulation could induce simultaneously lower pH and NOM removal, THM formation concentration is more effectively lowed than decreasing pH in the Nakdong river water.

본 연구는 낙동강 하류원수를 정수처리하는 정수장에서 전염소 처리시 pH 조절, 오존처리, 응집이 THMs 생성에 미치는 영향을 평가하기 위해 수행하였다. 원수의 pH를 낮추면 전염소 처리에 의해 THMs 생성이 저감되었다. pH를 9.5에서 9.0로 낮추면 THMs 생성이 18.3%, 9.0에서 8.0으로 낮추면 14%, 8.0에서 7.0으로 낮추면 7%, 9.5에서 8.0으로 낮추면 29% 감소되었다. 염소처리 전에 저농도의 오존($0.11{\sim}0.48mg{\cdot}O_3/DOC$)을 주입하면 오존을 주입하지 않은 경우에 비해 THMs 생성을 6~24% 정도 저감시킬 수 있었다. 전오존 1.0 mg/L을 주입한 원수에 염소 2.5 mg/L를 주입하고 alum 40 mg/L, 황산 6 mg/L를 주입한 경우 THMs 생성농도가 염소만 처리한 경우에 비해 42% 감소하였다. 정수처리공정에서 전오존 처리 후에 염소를 투입하고 응집이나, pH 조절을 하면 취수구에서 pH만 낮추는 경우에 비해 THMs 제어에 더 효과적이다. 염소 2.5 mg/L를 주입한 후 alume 40 mg/L 주입하여 응집실험을 한 결과, THMs 생성농도가 염소만 투입한 경우에 비해 pH 저하로 인해 19%, 천연 유기물질(NOM)의 제거로 18% 정도 저감되었다. 응집은 pH 저하와 유기물 제거를 동시에 유발하기 때문에 pH를 낮추는 경우에 비해 THMs 생성농도 저감에 효과적이었다.

Keywords

References

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