Energy recovery and activation of biochar from kenaf, manure, and food waste via pyrolysis

Energy recovery and activation of biochar from three types of biomass waste [kenaf (agricultural waste), manure (livestock waste), and dried food waste (municipal organic waste)] were achieved via pyrolysis. The yields of biochar, bio-oil, and syngas as well as the heating values of biochar (9.0-19.6 MJ/kg) and bio-oil (23.8-29.5 MJ/kg) showed that these two products can be used as supplementary fuels for incinerators and power plants. The yields of methane and hydrogen during the pyrolysis of dried food waste were 0.018 mmol/g and 0.065 mmol/g in 10 min, respectively, revealing that syngas can also be used as a source of energy. In addition, biochar may be a potential supplementary fuel and sorbent for environmental remediation. Steam activation at 900 oC enlarged the specific surface area of biochar by 1-2 orders of magnitude (from 6.8-32.3 to 104-419 m2/g). As a result, the sorption of 2,4-dinitrotoluene and 4-chlorophenol to the steam-activated biochar was greatly enhanced. However, the sorption of chromate and selenate to steam-activated biochar was not significant regardless of enhanced surface area, suggesting that other sorption mechanisms like surface complexation may be involved in the sorption of chromate and selenate. Our results suggest that the pyrolysis of various types of biomass waste can be a promising option for disposing of waste and generating valuable energy products for promoting sustainability.