In this study, fast microwave-assisted catalytic pyrolysis of sewage sludge was investigated for bio-oil production, with HZSM-5 as the catalyst. Pyrolysis temperature and catalyst to feed ratio were examined for their effects on bio-oil yield and composition. Experimental results showed that microwave is an effective heating method for sewage sludge pyrolysis. Temperature has great influence on the pyrolysis process. The maximum bio-oil yield and the lowest proportions of oxygen- and nitrogen-containing compounds in the bio-oil were obtained at 550. °C. The oil yield decreased when catalyst was used, but the proportions of oxygen- and nitrogen-containing compounds were significantly reduced when the catalyst to feed ratio increased from 1:1 to 2:1. Essential mineral elements were concentrated in the bio-char after pyrolysis, which could be used as a soil amendment in place of fertilizer. Results of XRD analyses demonstrated that HZSM-5 catalyst exhibited good stability during the microwave-assisted pyrolysis of sewage sludge.
Bibliographical noteFunding Information:
The authors would like to express their great appreciation to Minnesota Environment and Natural Resources Trust Fund, North Central Regional Sun Grant Center at South Dakota State University through a Grant provided by the U.S. Department of Agriculture ( 2013-38502-21424 ) and a Grant provided by the U.S. Department of Transportation , Office of the Secretary ( DTOS59-07-G-00054 ), and University of Minnesota Center for Biorefining , as well as China Scholarship Council (CSC), High Technology Research and Development Program of China ( 2012AA021704 , 2014AA022002 ), Beijing Municipal Science and Technology Commission ( z141109004414002 ), International Science and Technology Cooperation Program of China ( 2014DFA61040 ), National High-tech R&D Program of China ( 2012AA021205 ), National High-tech R&D Program of China ( 2012AA101809 ), Natural Science Foundation of China ( 21266022 ) for their financial support for this work. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program.
- Sewage sludge