|Guo, Mingxin -|
|Shen, Yufang -|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: October 24, 2011
Publication Date: November 13, 2012
Citation: Guo, M., Shen, Y., He, Z. 2012. Poultry litter-based biochar: preparation, characterization, and utilization. In: He, Z., editor. Applied Research of Animal Manure: Challenges and Opportunities beyond the Adverse Environmental Concerns. New York, NY:Nova Science. p. 169-202. Technical Abstract: Disposal of poultry litter (PL) by land application in concentrated bird production regions has resulted in severe water eutrophication issues. Given its high lignocelluosic content and low moisture, PL can be readily converted into agriculture-use biochar through farm-scale slow pyrolysis, with bio-oil and syngas as co-products for additional value. In slow pyrolysis, peak temperature is the key factor determining the biochar yield and quality. Generally, pyrolyzing PL with increasing peak temperature in 300–600°C results in decreases in yield, total N content, organic carbon (OC) content, cation exchange capacity (CEC), and negative surface charges, but increases in ash content, OC recalcitrance, pH, and BET (Brunauer-Emmett-Teller) surface area of the biochar products. In this chapter, we presented, as a case study, a simple slow pyrolysis system for easily scaling-up-to-farm conversion of PL into biochar and bio-oil, and details involved in characterizing the generated biochars. The PL biochars generated at 300–600°C using such a system showed yields 45.7–60.1% of the feed mass, pH 9.5–11.5, OC 325–380 g kg-1, and recalcitrant OC 140–295 g kg-1. The products demonstrated BET surface area 2.7–5.8 m2 g-1, water holding capacity (WHC) 0.88–1.10 g g-1, and CEC 21.6–36.3 cmolc kg-1 and contained total N, P, and K 1.2–41.7, 22.7–30.5, and 69.3–91.5 g kg-1, respectively. Pyrolysis transformed PL nutrients into predominantly water unextractable forms and at pyrolysis temperature >400°C the majority of feed N was lost in volatiles. Slow pyrolysis at 300°C conserved most PL nutrients in biochar and increased the water soluble N:P ratio from 2.6:1 to 14.3:1. The maximal recovery of feed OC as biochar recalcitrant OC occurred at 500°C. Poultry litter-derived biochar can be used in crop cultivation and environmental applications for improving soil fertility, enhancing carbon sequestration, reducing greenhouse gas emissions, and remedying pesticides and heavy metal-contaminated soils. Slow pyrolysis at 300–500°C is recommended to produce PL biochar for soil applications at 20–60 tons ha-1.