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Poultry Digestion - Emerging Farm-Based Opportunity

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Full proceedings at: http://www.extension.org/72952 While EPA AGSTAR has long supported the adoption of anaerobic digestion on dairies and swine farms, they have not historically focused on the use of anaerobic digestion on egg laying and other poultry facilities. This has been because the high solids and ammonia concentrations within the manure make anaerobic digestion in a slurry-based system problematic. Development of enhanced downstream ammonia and solids recovery systems is now allowing for effective digestion without ammonia toxicity. The process also generates dilution water, avoiding the need for fresh water consumption, and eliminating unwanted effluent that needs to be stored or disposed of to fields. The system produces high-value bio-based fertilizers. In this presentation, a commercial system located in Fort Recovery Ohio will be used to detail the process flow, its technologies, and the co-products sold.

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Poultry Digestion - Emerging Farm-Based Opportunity

  1. 1. Poultry Digestion: Emerging Farm- Based Opportunity Craig Frear, Chad Kruger Center for Sustaining Agriculture and Natural Resources Washington State University Photo: Andgar
  2. 2. Outlines 1. Poultry Statistics/Ammonia 2. Concerns with AD of poultry 3. Example 4. Conclusion Photo: DVO
  3. 3. Poultry Statistics/Ammonia Photo: Jim Jensen
  4. 4. Poultry Statistics: Layers Layers/Broilers • 387 farms with 269 M or 77% of market~700K mean (Layers) and 33,000 farms with 8.5 B or 67% of market~250K mean (Broilers). • 20-30 lbs. fresh manure per day per 100 layers at 75% moisture • Naturally dry during storage, achieving 20- 60% dry solids • High nutrient content (dry values) • Organic C 15.3% • Nitrogen 3.3% • Phosphorus 2.9% • Calcium 17.9% USDA/NASS 2012 Census; Ohio State University Extension—ANR-4-98 wattagnet.com labexkorea.wordpress.com
  5. 5. Ammonia Emissions • 16-21 g NH3 year-1 hen-1 from belt manure systems with forced air systems producing less • 13 ppm NH3 from house exhaust • 116 g NH3 year-1 hen-1 from compost of manure • 123-167 ppm NH3 compost exhaust worldpoultry.net xrpoultry.com Fournel et al, 2012; Zhao et al, 2008; Ni et al., 2012 (image)
  6. 6. Concerns with Poultry AD Photo: Jim Jensen
  7. 7. High Solids Content and Ammonia • Singh et al., (2010) in their review paper summarize that poultry manure digestion without co-digestion is only feasible at TS < 6% and even then prone to upset and failure due to ammonia toxicity • Ward (2003) concluded that of all treatment options for poultry manure, only pellets and compost were economically viable, ruling out AD as non-viable due to ammonia toxicity, dilution concerns and non-nutrient resolution • Recent papers have emphasized ammonia stripping prior to digestion so as to resolve most if not all of the AD concerns (Singh et al., 2010).Gamble, unpublished data
  8. 8. Example Photo: Jim Jensen
  9. 9. Ohio Egg Layer AD Example
  10. 10. Ohio Egg Layer AD Example
  11. 11. Ohio Egg Layer AD Example Stored manure solids (30-50% total solids) are transported to be mixed with return water from the digestion and nutrient recovery process. The mixing process produces an influent of about 9% total solids and a flow rate of about 500 tons day-1 with an ammonia concentration of about 2,500-3,000 mg N L-1. A nearly closed-loop is developed with 85% of effluent recycled back to the front end of the system—the missing 15% of effluent is lost during drying and is replaced with egg wash water.
  12. 12. Ohio Egg Layer AD Example The influent is digested in an approximate 25 day residence anaerobic digester operating at 100F. Biogas produced from the process is sent to an engine/generator set to produce electricity to the grid and recovered waste heat which is used to maintain digester temperature and dry solids.
  13. 13. Ohio Egg Layer AD Example Effluent, not at ammonia concentrations of 3,800-4,000 mg N L-1 is then sent to an ammonia stripping system to recover the ammonia as gas and then contact with sulfuric acid to make ammonium sulfate fertilizer for sales. Resulting ammonia concentrations after treatment are approximately 1,500 mg N L-1
  14. 14. Ohio Egg Layer AD Example After the ammonia is recovered, the remaining effluent is sent to a dissolved air flotation (DAF) system for removal of fine solids and phosphorus. The system produces a wastewater that is 2.5% total solids and has 85% of the phosphorus removed. Product flows from the nutrient recovery are: • ~ 1.2 tons of ammonia is recovered day-1, to produce roughly 15 tons of ammonium sulfate solution (8% nitrogen) or upon drying 5-6 tons of ammonium sulfate solids day-1 (21% N, 24% S) • ~ 23 tons of dry nutrient solids day-1 with nutrient values of (21% C, 4% N, 6% P, 1% K, 10% Calcium, 3% Magnesium + other micronutrients)
  15. 15. Conclusion Photo: Jim Jensen
  16. 16. Conclusion • Presently seven poultry digester operations exist on farms in the US, many of them practicing direct anaerobic digestion of poultry manure and/or off-farm substrates in a dilute manner to avoid ammonia toxicity. • Numerous citations in literature as well as emerging commercial systems endeavor to make a larger bio-refinery around the poultry digestion concept, incorporating advance ammonia and solids recovery so as to avoid inhibition and reduce volume of wastewater produced. • Existing refinement in choice and performance of technologies used in the systems is on-going as is market maturity for developed fertilizers and techno-economics for overall viability of such projects. • Given enhancements and continued demonstration, poultry manure digestion for combined production of biogas (electricity or CNG) and fertilizer with a near closed-loop use of waste liquids holds strong potential. • This potential is now just being realized with several such poultry projects being pitched in the Chesapeake Region
  17. 17. This research was supported by funding from USDA National Institute of Food and Agriculture, Contract #2012- 6800219814; and from the WSU Agricultural Research Center; Acknowledgements
  18. 18. Contact Information Craig Frear, PhD Assistant Professor Washington State University PO Box 646120 Pullman WA 99164-6120 509-335-0194 cfrear@wsu.edu

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