Conversion of poultry wastes into energy feedstocks

• Biochars from hydrothermal carbonization of poultry litter had lignite properties.
• Biochars from pyrolysis of poultry litter were close to bituminous coal.
• HTL of poultry meal yielded a bio-oil having high calorific value.
• Nitrogen in bio-oils remains a major challenge to producing commercial fuels.
• Aqueous solution from hydrothermal liquefaction can be used as nitrogen fertilizer.

In this study, conversion of wastes from poultry farming and industry into biochar and bio-oil via thermochemical processes was investigated. Fuel characteristics and chemical structure of biochars and bio-oils have been investigated using standard fuel analysis and spectroscopic methods. Biochars were produced from poultry litter through both hydrothermal carbonization (sub-critical water, 175–250 °C) and pyrolysis over a temperature range between 250 and 500 °C. In comparison to hydrothermal carbonization, pyrolysis at lower temperatures produced biochar with greater energy yield due to the higher mass yield. Biochars obtained by both processes were comparable to coal. Hydrothermal liquefaction of poultry meal at different temperatures (200–325 °C) was conducted and compared to optimize its process conditions. Higher temperatures favored the formation of bio-crude oil, with a maximum yield of 35 wt.% at 300 °C. The higher heating values of bio-oils showed that bio-oil could be a potential source of synthetic fuels. However, elemental analysis demonstrated the high nitrogen content of bio-oils. Therefore, bio-oils obtained from hydrothermal liquefaction of poultry meal should be upgraded for utilization as a transport and heating fuel.