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United States Department of Agriculture

Agricultural Research Service


Location: Commodity Utilization Research

2012 Annual Report

1a.Objectives (from AD-416):
The research objectives are to develop slow pyrolysis (or torrefaction) and activation processes to convert agricultural feedstock (crop residues, manures, processing wastes, and biorefinery by-products) into: (1) chars that can be used as industrial adsorbents; (2) chars that can be used as soil amendments which improve soil quality, water quality, and sequester carbon; (3) chars that can be used as energy sources (in combustion or gasification); and (4) bio-gas and bio-oil co-products that provide some of the heat and power requirements of the pyrolysis/torrefaction/activation operations and possibly excess heat/power for sale.

1b.Approach (from AD-416):
The approach will be to take agricultural feedstocks (crop residues, animal manure, and biorefinery waste) and heat them under different gas atmospheres to a set temperature. In order to create chars for target applications, the temperature, heating time, and gas atmosphere will be varied, as well as performing pretreatment (before heating) or post treatment of the chars to obtain desired properties. The products will be tested for target applications in our laboratories and also with collaborators with expertise in ammonia adsorption, soil amendments, bio-oil production, and large-scale pyrolysis.

3.Progress Report:
The reported progress addresses Objectives 1 and 2 of the research project and focuses on the goal of National Program 213 and 306 action plans.

Long-term effectiveness of biochar for heavy metal stabilization depends upon biochar’s sorptive property and stability in soil. To understand the role of different chemical groups that exist on the surface of the biochar and how they affect heavy metal stabilization, biochars were made from cottonseed hull and flax shive. In another study, phosphorous-rich biochar from chicken manure was produced at two different temperatures (350 and 650° Celsius) and these chars were added to contaminated soils. It was found that biochar created at the lower of the two temperatures could stabilize the metals better. Two manuscripts were published about the results.

Sorption and degradation are the primary processes controlling the efficiency and runoff contamination risk of pesticides. In one study, we investigated how the soil type (clayey, acidic Puerto Rican forest soil and heavy metal contaminated small arms range soils of sandy and peaty nature) impacted the sorption of several pesticides (which names are triazine, malathion, parathion, and diazinon) to the soil. The degree of sorption on different soils showed the following increasing trend: triazineA literature review was conducted to determine the up-to-date knowledge of biochar made from sugarcane bagasse. The review was published as a book chapter in a book about biorefinery co-products.

Work with collaborators used a technique called Fourier Transform Infrared (FTIR) Spectroscopy and other advanced analytical methods to look at biochars created at two different temperatures (350 and 700° Celsius) from animal manure. Dairy biochars contained the greatest volatile matter (things that volatilize at high temperatures), carbon, and energy content and lowest ash, nitrogen, and sulfur contents. Swine biochars had the greatest phosphorous, nitrogen, and sulfur contents. Turkey biochars exhibited the greatest ash contents. A manuscript was published with the results.

Work with collaborators studied ten biochars pyrolyzed from five feed stocks at two temperatures, and their physical and chemical properties were characterized. Biochars were mixed with different type of soils and kept in pots for 127 days. Switchgrass biochar caused the most significant moisture storage improvements. In another study, 70 biochars were studied in a method which slowly heat up the material and the gases that are coming off are collected and analyzed. These gases are probably the same chemicals that would interact with microorganisms that are in the soil. It was found that the process by which the biochar had been made greatly affected the type of gases that would come off and it was suggested that this type of analysis should probably be performed before adding biochar to soil. Two manuscripts were published with the results.

1. Heavy metals were stabilized in contaminated soils. Industrial and military sites are of considerable environmental risk when the soil contains toxic heavy metals. In collaboration with Army Research Laboratory and U.S. Department of Defense partners, ARS scientists at the Southern Regional Research Center in New Orleans, LA, demonstrated specific bindings of lead, copper, and zinc by carboxyl surface functional groups of biochar. Based on that, we developed biochar activation protocols for increasing the amount of oxygen-containing groups for selective metal binding. We also demonstrated that phosphorous and other elemental characteristics of manure biochars can be used to predict heavy metals stabilization in contaminated soils. This is positive news as there are an estimated 12,000 military and non-military shooting ranges where lead is the major risk driver and legislative concern.

2. Activated chars made from almond shells were used to clean up water. Aquifer drinking water in San Joaquin Valley, CA, is contaminated with a compound called dibromochloropropane from pest treatments. The water is filtered with large activated carbon filters before introduced into city drinking water systems. ARS researchers at the Southern Regional Research Center in New Orleans, LA, charred almond shells and then activated them with steam. These activated chars were then tested for their capability of removing the contaminants from water. Laboratory experiments were so successful that the researchers built a small column and installed it at a well site in CA and operated it for several months at 100% removal efficiency. A large number of these wells exist in the San Joaquin Valley and it would be beneficial if sustainable resources such as local almond shells could be used as replacement products for activated carbons from coal.

Review Publications
Uchimiya, M., Bannon, D.I., Wartelle, L.H. 2012. Retention of heavy metals by carboxyl functional groups of biochars in small arms range soil. Journal of Agricultural and Food Chemistry. 60(7):1798-1809.

Uchimiya, M., Wartelle, L.H., Boddu, V.M. 2012. Sorption of triazine and organophosphorus pesticides on soil and biochar. Journal of Agricultural and Food Chemistry. 60(12):2989-2997.

Klasson, K. T. 2012. Char from sugarcane bagasse. In: Carrier, J., Ramaswamy, S, Bergeron, C., editors. Biorefinery Co-products: Phytochemicals, Primary Metabolites and Value-added Biomass Processing. Chichester, U.K.: John Wiley & Sons. Chapter 15, p. 327-350.

Cantrell, K.B., Hunt, P.G., Uchimiya, S.M., Novak, J.M., Ro, K.S. 2012. Impact of pyrolysis temperature and manure source on physicochemical characteristics of biochar. Bioresource Technology. 107:419-428.

Spokas, K.A., Novak, J.M., Stewart, C.E., Cantrell, K.B., Uchimiya, S.M., Dusaire, M.G., Ro, K.S. 2011. Qualitative analysis of volatile organic compounds on biochar. Chemosphere. 85(5):869-882.

Novak, J.M., Busscher, W.J., Watts, D.W., Amonette, J., Ippolito, J.A., Lima, I.M., Gaskin, J., Das, K.C., Steiner, C., Ahmedna, M., Rehrah, D., Schomberg, H.H. 2012. Biochars impact on soil moisture storage in an Ultisol and two Aridisols. Soil Science. 177(5):310-320.

Uchimiya, M., Bannon, D.I., Wartelle, L.H., Lima, I.M., Klasson, K.T. 2012. Lead retention by broiler litter biochars in small arms range soil: Impact of pyrolysis temperature. Journal of Agricultural and Food Chemistry. 60:5035-5044.

Last Modified: 4/19/2014
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