Location: Commodity Utilization Research2010 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
Considerable progress has been made on the process for developing advanced materials to remove (or stabilize) pollutants in soil, water, and air or to serve as an additive to soil. Future work will also investigate the possibility of using these materials as fuels. Steam-activated biochars (charcoal created by pyrolysis of biomass) from poultry (chicken or turkey) manure were shown to remove elemental mercury from air streams, as well as, or better than, an often used commercial alternative. It was shown that post-treatment washing sometimes resulted in an improvement in performance, but with other manure types it was not advantageous to wash the activated chars. Overall, the best performing activated chars were unwashed steam-activated chars from chicken litter and turkey cake. Poultry manure was pelletized, sterilized, and shipped to a collaborator for testing of the heating process on a larger scale. In separate experiments, both un-activated and steam-activated biochars from chicken litter was tested for how well they would tie up toxic metals in soil or water. The results show that biochar amendment significantly helped the soil contain the metals. Part of this was explained by the increase in alkalinity when biochars were added. Un-activated materials were also shared with other Agricultural Research Service researchers for characterization as soil nutrient amendments or water holding capacity. The poultry based chars did little to retain water and was found to serve as an excellent source for phosphorous. A process developed to make steam-activated chars (or carbons) from shells of different almond varieties was completed and published. The results showed that the steam-activation process was robust enough to produce a material that consistently adsorbed a nematicide (chemical used to kill plant parasites) commonly found in groundwater in areas were almonds are grown.