Slow pyrolysis of poultry litter and pine woody biomass: Impact of chars and bio-oils on microbial growth

Abstract

Accidental or prescribed fires in forests and in cultivated fields, as well as primitive charcoal production practices, are responsible for the release of large amounts of gases, char and condensable organic molecules into the environment. This paper describes the impact of condensable organic molecules and chars resulting from the slow pyrolysis of poultry litter, pine chips and pine pellets on the growth of microbial populations in soil and water. The proximate and elemental analyses as well as the content of proteins, cellulose, hemicellulose, lignin, and ash for each of these bio-materials are reported. The yields and some properties of char and condensable liquids are also documented. The behavior of microbial populations in soil and water is followed through respiration studies. It was found that biological activity was highest when aqueous fractions from poultry litter were applied in water. Cumulative oxygen consumption over a 120-h period was highest in the aqueous phases from poultry litter coarse fraction (1.82 mg/g). On average the oxygen consumption when oily fractions from poultry litter were applied represented 44 to 62% of that when aqueous fractions were applied. Pine chip and pine pellet derived liquids and chars produced respiration activity that were an order of magnitude lower than that of poultry litter liquid fractions. These results suggest that the growth observed is due to the effect of protein-derived molecules.

Keywords:

• Pyrolysis
• underground incinerations
• smoke
• soil respiration
• Terra Preta
• bio-oils
• chars

Acknowledgments

The authors would like to thank the Fiber Committee of the Georgia Traditional Industries Pulp and Paper Research Program. Thanks are also due to Mr. Blair Winsor and to Mr. Ryan Hunt for their contributions in the experimental work.

Notes

∗Solid residue

∗By difference.