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United States Department of Agriculture

Agricultural Research Service

Research Project: HYDROTHERMAL CARBONIZATION OF AGRICULTURAL RESIDUALS

Location: Coastal Plain Soil, Water and Plant Conservation Research

2013 Annual Report


1a.Objectives (from AD-416):
To gain mechanistic understanding of hydrothermal carbonization process involving various agricultural residuals such as livestock wastes and crop residues.


1b.Approach (from AD-416):
Carbonization: Dried and grounded swine manure, chicken litter, and rye grass will be carbonized under water in stainless steel batch reactors at reaction temperatures of 200 to 350°C and autogenic pressures. Solid separated swine manures from a private swine farm in NC and chicken litter from a private farm in SC will be used for the experiments. Some of the animal manure feedstock will be carbonized with the catalysts prepared by NC State University (Agreement #: 58-6657-9-234N). The carbonization reactor system includes a non-stirred 1-L T316 stainless steel vessel with a band heater capable of heating the reactant to 500°C and a pressure of 3000 psig. Small stainless steel tubular reactors (180 mL volume) will also be used to quickly screen appropriate process variables for the reactions involving low temperature and pressure (less than 250°C and 5 Mpa). The feedstock will be carbonized under water by slowly heating the reactor (about 5°C/min) to 200-350°C. Some of the boichar (or hydrochar) will be heated higher temperature in a furnace to about 850°C with steam for activation. Gas, liquid, and solid end products will be analyzed for their physicochemical and thermal properties.

Physicochemical Characterization: Gaseous end products will be analyzed with gas chromatographs equipped with thermal conductivity and flame ionization detectors and mass spectrometer for main energy gases and hydrocarbons. Solid end product, biochar, will be washed with acetone to remove tarry residue on its surface. Biochar will be characterized with its functional groups, surface areas, contact angles, calorific values, adsorption capacity for various metals and gases, pyrolytic and oxic thermal degradation patterns, and ash contents. Impact of applying biochar to soil fertility will also be tested. Aqueous and non-aqueous liquid products will be analyzed with a GC/MS and HPLC.


3.Progress Report:

This research supports project objective 2: Develop renewable energy via thermochemical technologies and practices for improved conversion of manure into heat, power, biofuels, and biochars.

Prepared gas, liquid, and solid product samples from hydrothermally carbonizing swine solids and chicken litter. The (PIs) analyzed the product gas compositions using gas chromatography-mass spectroscopy (GC-MS). The PIs conducted analyses of surface areas of both animal manure based hydrochars and chemically activated hydrochars. Analytical results indicated that chemically activated hydrochars had very high surface areas. The PIs also conducted adsorption isotherm experiments using swine hydrochar with atrazine. Based on soil incubation studies, the swine manure hydrochar without acetone washing stage significantly promoted soil respiration due to high level of labile organic compounds accumulated on the hydrochar surface.


Last Modified: 10/20/2014
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