Physical Properties and Pyrolysis Behavior of Fractionated Poultry Litter

Abstract

Due to environmental issues with the use of poultry litter for land application, alternative means for its value-added utilization need to be identified. One possible solution is the fractionating of poultry litter into a nutrient-rich fine fraction that can be used as fertilizer and a coarser fraction that has the potential of being used as bioenergy feedstock. In this study, physical properties relevant to storage, handling, and processing of poultry litter that were separated into three fractions (with average diameters of 0.396, 0.708, and 1.181 mm) were determined. The densities (bulk, particle, and tap) of the fractions increased with fraction size. The fine fraction was the most compressible and was the dominant contributor to the compressibility of unfractionated poultry litter. The coarse fraction was the least compressible. The flow index values of the coarse, middle, and fine fractions were 16.1, 13.2, and 11.5, respectively, and were significantly higher than the flow index of unfractionated poultry litter (3.6). The heating value, the carbon content, and the rate of thermal decomposition of the fractions increased with increase in particle size of the fractions. Maximum pyrolysis rates of 0.107 min-1, 0.126 min-1, and 0.154 min-1 were obtained for the fines, middle, and coarse fractions, respectively. For all fractions, the activation energy was highest for cellulose decomposition (133 to 145 kJ/mol) and lowest for lignin decomposition (45 to 56 kJ/mol). The reaction order varied from 0.64 to 2.23.