Title: Co-pyrolysis of swine manure with agricultural plastic waste: Laboratory-scale study Authors
Submitted to: Journal of Waste Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 3, 2014
Publication Date: May 7, 2014
Citation: Ro, K.S., Hunt, P.G., Jackson, M.A., Compton, D.L., Yates, S.R., Cantrell, K.B., Chang, S. 2014. Co-pyrolysis of swine manure with agricultural plastic waste: Laboratory-scale study. Journal of Waste Management. 34(8):1520-1528. DOI:10.1016/j.wasman.2014.04.001. Interpretive Summary: Researchers report that manure-derived biochar, the solid product obtained from heating animal manures without air (i.e., pyrolysis), has considerable potential both to improve soil quality and reduce water pollution. However, one of the obstacles for obtaining manure biochar is the high energy requirement of the pyrolyzing wet animal manures. This research investigated the feasibility of utilizing agricultural plastic film wastes to supplement the energy needed for producing manure biochar. Our study showed that pyrolyzing mixtures of swine solids with plastic mulch film wastes produced combustible gas with heating values much higher than that of natural gas. Furthermore, commonly used fumigants were not detected in the emitted gas from the pyrolysis process. The biochar produced from swine solids mixed with plastic mulch film wastes was not different from that produced from swine solids alone. Further energy analyses showed that only about 10% plastic mulch film mixture was needed to meet the pyrolysis energy requirements. If more than 10% plastic mulch film mixtures were used, the pyrolysis process generated surplus gas energy which could be used to generate power. The results of this study demonstrated the potential of using pyrolysis technology to manage two prominent agricultural waste streams (plastic mulch film wastes and swine solids) while producing value-added biochar and a power source that could be used for local farm operations.
Technical Abstract: Manure-derived biochar is the solid product resulting from pyrolysis of animal manures. It has considerable potential both to improve soil quality with high levels of nutrients and to reduce contaminants in water and soil. However, the combustible gas produced from manure pyrolysis generally does not provide enough energy to sustain the pyrolysis process. Supplementing this process may be achieved with spent agricultural plastic films; these feedstocks have large amounts of available energy. Plastic films are often used in soil fumigation. They are usually disposed in landfills, which is wasteful, expensive, and environmentally unsustainable. The objective of this work was to investigate both the energetics of co-pyrolyzing swine solids with spent plastic mulch films (SPM) and the characteristics of its gas, liquid, and solid byproducts. The heating value of the product gas from co-pyrolysis was found to be much higher than that of natural gas; furthermore, the gas had no detectable toxic fumigants. Energetically, sustaining pyrolysis of the swine solids through the energy of the product gas could be achieved by co-pyrolyzing dewatered swine solids with just 10% SPM. If more than 10% SPM is used, the co-pyrolysis would generate surplus energy which could be used for power generation. Biochars produced from co-pyrolyzing SPM and swine solid were similar to swine solid alone based on the surface area and the nuclear magnetic resonance spectra. The results of this study demonstrated the potential of using pyrolysis technology to manage two prominent agricultural waste streams (SPM and swine solids) while producing value-added biochar and a power source that could be used for local farm operations.