Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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An Energy Characteristics of Carbonization Residue produced from Sewage Sludge Cake

하수슬러지 케익으로부터 생산한 탄화물의 에너지 특성

  • 이승희 (경기대학교 공과대학 환경공학과)
  • Received : 2009.01.20
  • Accepted : 2009.02.06
  • Published : 2009.04.30
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Abstract

Sewage sludge cake(SSC) is seriously concerned because ocean dumping, which is the cheapest treatment method now, will be banned in 2012. On the basis of this reason, recycling of SSC is emphasized to convert the treatment method. One of the method to recycling SSC could be carbonization process which also can be reduced greenhouse gas effectively. And carbonization residue of SSC produced by carbonization process can become a renewable energy source. However, carbonization process has not been evaluated by considering basic operating data such as heating value, yield and fuel ratio. In this study, the basic characteristics of SSC such as proximate analysis, elementary analysis and heating value are analyzed. In carbonization process, the effect of carbonization temperature and time on the residue of SSC are estimated. And the analysis is carried out to obtain basic properties of the residue of SSC. From the result of chemical composition of SSC residue, there is 27% of phosphate in SSC. Phosphate will take a role of reductant to convert from hazardous substance to non-hazardous material. As increased carbonization temperature and time, heating value and yield are decreased but fuel ratio(fixed carbon/volatile combustible) of the residue is increased. In the carbonization process, the optimum temperature and time in carbonization test for SSC can be decided by $250^{\circ}C$ and 15 min, respectively. However, the carbonization residue of SSC can not be deserved to use one of renewable energy sources because the heating value at the optimum condition is relatively low. Hence, it is desirable that SSC can be mixed with other organic waste to carbonize.

국내 하수슬러지는 2012년부터 런던협약에 의해 해양투기가 금지될 예정에 있어 이에 대한 처리방법이 절실한 실정이다. 본 연구에서는 하수슬러지 케익을 재활용하기 위한 방법으로 탄화공정을 이용하여 탄화물 제조 및 에너지 특성에 대한 검토를 실시하였다. 하수슬러지 케익의 기초적 특성과 조성에 의하면, 하수슬러지 케익에는 27%의 인산염이 포함되어 있으며 이는 환원제로서 유해물질 처리에 이용될 수 있다. 하수슬러지 케익의 발열량을 파악한 결과, 저위발열량은 38.7 kcal/kg으로 하수슬러지 케익을 탄화하지 않고 직접 에너지원으로 사용하는 것은 바람직하지 않다. 하수슬러지 케익의 탄화공정에서 최적 탄화온도와 최적 탄화시간은 $250^{\circ}C$와 15분으로 설정되었다. 이 조건에서의 탄화물의 발열량은 비교적 낮아 하수슬러지 케익 탄화물 자체는 신재생 에너지원으로의 가능성은 크지 않다고 판단되나 인산염이 27% 정도가 포함되어 있어 다른 유기성 폐기물과 혼합하여 탄화하는 것이 적합하다고 판단되었다.

Keywords

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