Pyrolysis Treatment of Exotic Animal Dung: From Waste to Nutrient Source

¹ Department of Chemistry, Faculty of Education, Trnava University in Trnava, Priemyselná 4, P.O. Box 9, Trnava, SK-918 43, Slovak Republic
² Institute of Chemistry and Environmental Science, Faculty of Natural Sciences, University of SS. Cyril and Methodius in Trnava, J. Herdu 2, Trnava 917 01, Slovak Republic

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

This work focuses on evaluating the possibility of production pyrolysis material based on elephant dung as an input precursor in the slow pyrolysis process at a temperature of 450 °C and a residence time of 1 hour. The prepared biochar was subjected to physical and chemical characterization as well as a pilot ecotoxicological test. The polycyclic aromatic hydrocarbons (PAHs) concentrations found in biochar (BC) did not exceed the standard limits for basic quality biochar according to European Biochar Certificate (EBC). X-ray fluorescence spectrometer (RFS) analysis confirmed the significant presence of Fe (2400 mg/kg), Cu (309 mg/kg), Zn (211 mg/kg), Cr (106 mg/kg) and Ni (65 mg/kg) in the BC material examined. Based on the concentrations of the monitored metals, we concluded that BC does not meet the requirements for basic grade biochar according to EBC. However, an ecotoxicological test with barley confirmed that many of these potentially toxic elements are firmly fixed in biochar and not readily available to plants (Cu, Ni). Sequential extraction analysis of P forms in pyrolysis material showed a significant presence of NaHCO₃-extractable P and NaOH-extractable P, i.e. fractions that ensure slow release of P. Biochar had no negative effect on the germination of cress seeds.