Kinetic and Thermodynamic Analysis of Chicken Manure Pyrolysis for Sustainable Waste Management in the Poultry Industry

Abstract

This study explores the kinetics of the pyrolysis process applied to chicken manure as an environmentally sustainable waste management technique within the poultry industry. Pyrolysis, a thermochemical conversion method, involves the decomposition of organic materials in the absence of oxygen, yielding biochar, gases, and bio-oil. Experimental runs were conducted using a fixed-bed reactor, varying reactor temperature and heating rate settings. Pyrolytic conversion was determined by weighing the reactor contents before and after each run, allowing for the construction of pyrolytic conversion curves. Through the application of the Coats-Redfern method, the pyrolysis kinetics was determined. It was found that a second-order kinetics model exhibited better agreement with the experimental data than a first-order model, yielding coefficient of determination (R2) values ranging from 0.99 to 1.00, compared to 0.94 to 0.97 for the first-order model. The apparent activation energy (Ea) was estimated to fall within the range of 140.4 to 151.2 kJ/mol. Additionally, the pre-exponential factors (A) were found to be significantly high, on the order of 1010 min-1, suggesting a low pyrolytic reactivity. The calculated enthalpy of reaction (ΔH) ranged from 134.1 to 145 kJ/mol. Importantly, the energy barrier, represented by the difference between activation energy (Ea) and enthalpy of reaction (ΔH), was determined to be low at 7 kJ/mol. These findings indicate the potential for efficiently and sustainably valorizing chicken waste through pyrolysis. The outcomes of this study provide valuable insights into the kinetics and thermodynamics of chicken manure pyrolysis, supporting its adoption as an energy-efficient and environmentally sound waste management strategy within the poultry industry.