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Effect of Wet Milling on Scum Generation and Solubilization in Batch Ozone Reaction Using Digested Sludge

소화슬러지를 이용한 회분식 오존반응 시 습식분쇄가 스컴 생성과 가용화에 미치는 영향

  • Hong, Seong-Min (Department of Energy and Environment System Engineering, University of Seoul) ;
  • Lee, Dong-Hoon (Department of Energy and Environment System Engineering, University of Seoul) ;
  • Kim, Choong-Gon (Bio Resource Center, Institute for Advanced Engineering) ;
  • Shin, Hyun-Gon (Department of Energy and Environmental Engineering, Shinhan University)
  • 홍성민 (서울시립대학교 에너지환경시스템공학전공) ;
  • 이동훈 (서울시립대학교 에너지환경시스템공학전공) ;
  • 김충곤 (고등기술연구원 바이오자원순환센터) ;
  • 신현곤 (신한대학교 에너지환경공학과)
  • Received : 2019.06.03
  • Accepted : 2019.06.17
  • Published : 2019.06.30

Abstract

Sewage sludge treatment is increasing every year due to improvement of living and urbanization. However, interest in anaerobic digestion which is one of the recycling technology. There is anaerobic digestion of increasing due to limitations of ocean dumping and final disposal. But, the limit of anaerobic digestion efficiency due to the advanced treatment of sewage has been limited, and studies for solubilization technology have been actively conducted. Therefore, in this study, we aimed to investigate the variation of generation of scum and the solubilization efficiency in the application of pre-treatment of ozone reaction and the change of properties of digested sludge with wet milling. There are results of VS/TS increased by 4.4% and $SCOD_{cr}/TCOD_{cr}$ increased by 9.4% by wet milling alone. In addition, the increase of the specific surface area due to which the reduction of the particle size of the solid content of the sludge in the ozone reaction caused by wet milling decreased the generation rate of scum at 14.3% and increased VS/TS at 2.1%, compared with the ozone reaction alone. From these results, it is expected that the application of wet milling can be increased the contact efficiency with solids in the sludge during ozone reaction with suppress scum and increase the efficiency of the subsequent process in anaerobic digestion.

생활의 향상 및 도시화로 인하여 국내의 하수슬러지는 매년 증대되고 있으나, 해양투기 금지 및 최종처리의 한계로 자원화 방법 중 하나인 혐기성소화의 관심도가 높아지고 있다. 그러나 하수의 고도처리에 따른 혐기성 소화 효율의 한계로 이를 높이기 위한 가용화 기술에 대한 연구가 활발히 진행되고 있다. 특히 가용화 방법 중 경제적이고 유용한 기술로 알려진 오존은 스컴이 다량 발생되고, 제거에 대한 한계성이 있다. 따라서 본 연구에서 소화슬러지의 습식분쇄에 따른 성상변화 및 오존반응의 전처리로 적용 시 스컴의 발생 및 가용화 효율변화를 알아보고자 한다. 연구결과, 습식분쇄만으로 VS/TS는 4.4%, $SCOD_{cr}/TCOD_{cr}$이 9.4% 증대되어 가용화가 일어났다. 또한, 습식분쇄 적용에 따른 오존반응 시 슬러지의 고형분의 입경 감소에 따른 비표면적의 증가로 오존반응만한 경우에 비하여 스컴 발생속도는 14.3% 감소되고, VS/TS는 2.1% 증대 되었다. 이 때 가용화 효율도 23.3% 증가되는 것으로 나타났다. 이러한 결과로 볼 때, 본 연구를 통해 습식분쇄를 적용하여 오존반응 시 슬러지 중의 고형물과 접촉효율이 증가로 스컴의 생성 억제 및 가용화 증대로 후속공정인 혐기성 소화의 효율을 증대시킬 수 있을 것으로 기대된다.

Keywords

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Fig. 1. Schematic diagram and picture of test plant.

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Fig. 2. Variation of solids and CODcr in Digested Sludge.(a: TS&VS, b: TCODcr, c: SCODcr)

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Fig. 3. Variation of generation scum by wet milling with/without after ozonation. (a: wet milling without after ozonation, b: wet milling with after ozonation)

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Fig. 4. Variation of solids and CODcr in Digested Sludge with/without wet milling by ozonation. (a: TS&VS without wet milling, b: TS&VS with wet milling, c: TCODcr&SCODcr without wet milling, d: TCODcr&SCODcr with wet milling)

Table 1. Characteristic of Digested Sludge in O-Si

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