Multivariate optimization of pyrolysis process parameters for biochar production

Abstract

Poultry litter is an abundant agricultural waste that poses a health risk when improperly disposed. To mitigate this problem, poultry litter can be used as fuel in combustion. The objective is to develop models that can optimize pyrolysis parameters for improved biochar quality and yield. Prior, the poultry litter is demineralized to reduce inorganic elements. RSM–CCD method developed models and optimized temperature, particle size, and reaction time to determine the outputs (biochar yield, higher heating value, H/C ratio, and energy yield). The developed models were significant with a p–value < 0.05. Maximum biochar yield (59.49%) was obtained at optimum pyrolysis parameters of 300 °C, 2.47mm, and 15 min. Maximum higher heating value (22.2MJKg–1) and energy yield (70.00%) were obtained at 300 °C, 4.04mm, and 15 min. Low H/C ratio was 0.03 at 550 °C, 1.17mm, and 15 min. ANOVA analysis verified the validity and degree of fitness of the developed models. Low standard deviation (< 7.00), small coefficient of variation (< 14.00%), high R2 (> 0.80), low difference of Adjusted R2 and Predicted R2 (< 0.20) and high adequate precision (> 4.00) verified the model’s adequacy for good precision. Models’ desirability function was satisfactory (> 4) with a 5.00% deviation from experimental values.