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Pyrolysis of Dried Wastewater Biosolids Can Be Energy Positive
Author(s) -
McNamara Patrick J.,
Koch Jon D.,
Liu Zhongzhe,
Zitomer Daniel H.
Publication year - 2016
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143016x14609975747441
Subject(s) - biosolids , pyrolysis , biochar , waste management , pulp and paper industry , moisture , chemistry , environmental science , char , environmental chemistry , environmental engineering , organic chemistry , engineering
Pyrolysis is a thermal process that converts biosolids into biochar (a soil amendment), py‐oil and py‐gas, which can be energy sources. The objectives of this research were to determine the product yield of dried biosolids during pyrolysis and the energy requirements of pyrolysis. Bench‐scale experiments revealed that temperature increases up to 500 °C substantially decreased the fraction of biochar and increased the fraction of py‐oil. Py‐gas yield increased above 500 °C. The energy required for pyrolysis was approximately 5‐fold less than the energy required to dry biosolids (depending on biosolids moisture content), indicating that, if a utility already uses energy to dry biosolids, then pyrolysis does not require a substantial amount of energy. However, if a utility produces wet biosolids, then implementing pyrolysis may be costly because of the energy required to dry the biosolids. The energy content of py‐gas and py‐oil was always greater than the energy required for pyrolysis.