High temperature pyrolysis of sewage sludge as a sustainable process for energy recovery

KARACA C., Sozen S. , ORHON D., Okutan H. C.

WASTE MANAGEMENT, vol.78, pp.217-226, 2018 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 78
  • Publication Date: 2018
  • Doi Number: 10.1016/j.wasman.2018.05.034
  • Title of Journal : WASTE MANAGEMENT
  • Page Numbers: pp.217-226


This study explored the potential of high temperature pyrolysis for energy recovery from domestic sewage. It mainly defines optimum operating conditions to maximize syngas generation. A pyrolysis unit was operated in batch mode, at temperatures of 450, 600 and 850 degrees C, rotation speeds of 10, 40 and 60 Hz. The sludge had 6% moisture content; it contained 65% organic matter and involved a low calorific value of 13.535 kJ/kg dry matter. Pyrolysis at 850 degrees C and high rotation speed of 60 Hz yielded the highest conversion of sludge to syngas, with an average of 59% of the organic matter as syngas, 29% as tar and 12% as biochar. Pyrolysis enabled 74% of the energy recovery as syngas and tar. Continuous full-scale pyrolysis systems would further increase the syngas by recovering condensable gaseous products and/or recycling tar back into the pyrolysis unit. A unified approach for energy recovery management should equally consider what fraction of the energy contained in the wastewater was consumed and wasted before generating the sludge. Therefore, the adopted management scheme should also cover all design and operation parameters of the treatment plant, because this is how the energy is best conserved even before the sludge is generated. (C) 2018 Elsevier Ltd. All rights reserved.