Quality variations of poultry litter biochar generated at different pyrolysis temperatures

Producing biochar and biofuels from poultry litter (PL) through slow pyrolysis is a farm-based, value-added approach to recycle the organic waste. Experiments were conducted to examine the effect of pyrolysis temperature on the quality PL biochar and to identify the optimal pyrolysis temperature for converting PL to agricultural-use biochar. As peak pyrolysis temperature increased incrementally from 300 to 600 degrees C, biochar yield, total N content, organic carbon (OC) content, and cation exchange capacity (CEC) decreased while pH, ash content, OC stability, and BET surface area increased. The generated biochars showed yields 45.7-60.1% of feed mass, OC 325-380 g kg(-1), pH 9.5-11.5, BET surface area 2.0-3.2 m(2) g(-1), and CEC 21.6-36.3 cmol(c) kg(-1). The maximal transformation of feed OC into biochar recalcitrant OC occurred at 500 degrees C, yet 81.2% of the feed N was lost in volatiles at this temperature. To produce agricultural-use PL biochar, 300 degrees C should be selected in pyrolysis: for carbon sequestration and other environmental applications, 500 degrees C is recommended. (C) 2011 Elsevier B.V. All rights reserved.