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Effect of operating condition of electro-coagulation on the membrane filtration resistances of activated sludge

전기응집 조건이 활성슬러지 막 여과 저항에 미치는 영향

  • 홍성준 (호서대학교 나노바이오트로닉스학과) ;
  • 장인성 (호서대학교 나노바이오트로닉스학과)
  • Received : 2015.01.06
  • Accepted : 2015.03.12
  • Published : 2015.03.31

Abstract

MBR (Membrane Bio-Reactor) process is known to consume enormous energy to control membrane fouling. To solve this problem, electro-coagulation technique has been applied to MBR. A series of electro-coagulation was applied to activated sludge suspension under different current density condition. After the electro-coagulations, membrane filtration of the activated sludge suspensions was conducted to investigate the effect of electro-coagulation on the fouling. As current density increased 10 to 40A/m2, the total fouling resistance (Rc+Rf) decreased from 18 to 79%, showing that the electro-coagulation improved the membrane filtration efficiency. Both the organic concentration in bulk and the particles size distribution were not nearly changed before and after the electro-coagulation. The enhanced filtration efficiency might be due to the aluminum hydroxide generated from chemical precipitation, which can be acted as a dynamic membrane preventing a deposition of foulants on membrane surfaces.

MBR (Membrane Bio-Reactor) 공정은 막 오염을 해결하기 위해 막대한 에너지 소비를 하는 공정으로 알려져 있다. 이를 해결하기 위한 일환으로 전기응집 기술을 MBR에 적용하는 시도가 보고되고 있다. 본 연구에서는 전류밀도를 변화시켜가며 활성슬러지의 막 여과를 수행하여 전기응집이 막 오염 저감에 미치는 영향과 메커니즘을 파악하고자 하였다. 활성슬러지 혼합액을 전기응집한 후 회분식교반셀로 분리 막의 여과성능을 평가하였다. 전류밀도(A/m2)를 10에서 40으로 증가시켰을 때 총 오염 저항 (Rc+Rf) 값이 18%에서 79%까지 감소하여 전기응집으로 인해 분리 막의 여과성능이 향상됨을 확인할 수 있었다. 전기응집 전후로 유기물 농도와 활성슬러지 입도분포 변화는 거의 일어나지 않았다. 여과 성능의 향상은 수산화알루미늄, Al(OH)3이 생성되어 막 표면에 부착되면서 오염물질이 쌓이게 됨을 방지하는 역할, 즉 dynamic membrane 으로 작용하였기 때문인 것으로 판단되었다.

Keywords

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