Poultry Digestion: Emerging Farm-

Based Opportunity

Craig Frear, Chad Kruger

Center for Sustaining Agriculture and

Natural Resources

Washington State University

Photo: Andgar

Outlines

1. Poultry Statistics/Ammonia

2. Concerns with AD of poultry

3. Example

4. Conclusion

Photo: DVO

Poultry Statistics/Ammonia

Photo: Jim Jensen

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

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

exhaustworldpoultry.net

xrpoultry.com

Fournel et al, 2012; Zhao et al, 2008; Ni et al., 2012 (image)

Concerns with Poultry AD

Photo: Jim Jensen

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concerns (Singh et al., 2010).Gamble, unpublished data

Example

Photo: Jim Jensen

Ohio Egg Layer AD Example

Ohio Egg Layer AD Example

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.

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.

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

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)

Conclusion

Photo: Jim Jensen

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

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

Contact Information

Craig Frear, PhD

Assistant Professor

Washington State University

PO Box 646120

Pullman WA 99164-6120

509-335-0194

cfrear@wsu.edu