ARS | Publication request: Conversion of animal manure to chars and their use as adsorbents for select metal ions

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 2, 2007
Publication Date: March 30, 2008
Citation: Lima, I.M., Klasson, K.T. 2008. Conversion of animal manure to chars and their use as adsorbents for select metal ions (abstract). Residuals and Biosolids 2008 Traditions, Trends and Technologies Conference, March 30-April 2, 2008, Philadelphia, Pennsylvania.

Technical Abstract: Water quality and public health impacts of animal manure produced at large concentrated animal facilities prompted the need for viable solutions for their conversion and reuse. Our laboratory at the Southern Regional Research Center has shown that it is feasible to convert animal manure into granular activated carbons used for heavy metals remediation. Pyrolytic products or chars are low porosity, lower surface area materials that are intermediate products in the development of activated carbons. The present study relates to the development and use of chars made from animal manure that possess excellent adsorption properties, particularly with respect to the uptake of metal ions. Toxic metals contamination of various water sources is a significant problem in many parts of the United States. Chars, which can be produced from a number of precursor materials including coal, wood and agricultural plant wastes, have not been examined for remediation of this problem. In this study, chars were produced by pyrolyzing a pelletized sample of animal manure (sourced from poultry, dairy cow and swine) under nitrogen at 700°C and 800°C for 1 hour. Specific physical and adsorptive properties for the resulting chars were determined and compared to chars made from wood, coal and coconut shells. Char yields decreased with pyrolysis temperature and were highest for dairy manure and lowest for swine manure-based chars with poultry chars in the middle, and ranged between 37 to 48% and 30 to 37%, for 700 °C and 800°C pyrolysis, respectively. Surface areas ranged between 92 and 318 m2/g, and were highest for the poultry manure based chars. As far as the char’s ability to adsorb metal ions, best performing chars in order of adsorption efficiency were broiler manure char, turkey manure char, swine char and dairy char, with respectively 0.96, 0.62, 0.28 and 0.17 mmoles/g of Cu2+ adsorbed. Additionally, animal manure-based chars exhibited metal ion adsorption that far exceeded that of the reference chars, made from coal, wood or coconut shells, with negligent to no adsorption observed, under the same conditions. The conversion of readily available and renewable animal manures into chars for wastewater remediation might be an alternative to a disposal problem and at the same time create new markets for animal manures.