digested solids - forms, markets and trends
TRANSCRIPT
Digested Solids: Forms, Markets, and Trends
Jim JensenWashington State University Energy Program
Photo: Andgar
Coauthors: Craig Frear, Chad
Kruger, and Georgine Yorgey,
Center for Sustaining Agriculture and
Natural Resources, Washington State
University
Photo: Jim Jensen
No endorsements intended or given; products
shown are for illustration purposes only.
Focus on the digested solids
Diagram: US EPA, AgSTAR
Bedding, compost/soil amendments, NPK fertilizers, fiber products
Diagram: US EPA, AgSTAR
Mechanical separation technologies
Source: Katers, John. 2008. “Value-added opportunities for separated manure solids” presentation
Photos: US Farm Systems, dlsbiogas
• Screens:
–Stationary inclined (static) screens
–Vibrating screens
–Rotating screens
• Presses
–Roller presses
–Belt presses
–Screw presses
• Centrifuges
Separation system performance
Source: Katers, John. 2008. “Value-added opportunities for separated manure solids” presentation
• Separator efficiency: the amount of solids of
the total that is recovered
Efficiency rates can range from less than 5% to greater than 70%
Increase efficiency with polymers
• Solids content: the ratio of solids to water in the
recovered material
Expressed as percent solids
Studies range from approximately 12% to 40% or higher
Separation system advantages
Source: Katers, John. 2008. “Value-added opportunities for separated manure solids” presentation
• Screens:
Perform better with low solids effluent
Need to avoid clogging the screen
Balance screen openings with desired efficiency
• Presses:
Higher separation efficiencies
Higher solids contents
Often used following initial screening
Digestion + separation
• Digestion reduces volatile
solids, leaving quality fiber
• Makes N&P more plant
available
• Reduces odor
• Reduces pathogens
• Separation creates liquid
and solid fractions
• Fractions of NPK nutrients
Photo: DVO Photo: WSU
Photo: DVO Tables: WSU, Climate Friendly Farming
Digested solids - characteristics
Photo: DVO Tables: WSU, Climate Friendly Farming
Digested solids - characteristics
Bedding on dairy farms
• 1st choice often; offsets farm
costs, saves money
• Digestion reduces
pathogens; additional
treatment or drying can
stabilize material further
• Compare to cost of other
bedding, e.g., sawdust
Photo: DVO Photos: Dorset GM; DT Environmental
“It was getting increasingly difficult to get sawdust for bedding and what we could get
was very expensive. Being able to produce bedding from the digested solids is a
significant benefit.” Peter Gebbie, Maplehurst Farm, VT
Composts and soil amendments
• Composting adds value to
unprocessed manure and
digested fiber
• Further reduces pathogens
• Stabilizes the organics,
making it safer for plants
• Gives it that darker, “richer”
compost color
• Digested solids can be part
of a compost mix
Photo: DVO Photos: pinterest, masterofhort
Organic certification
1. Certifications are a visible
signal or quality
2. Third-party verification
3. Meets requirements of a
high-value sector of the
market
4. May be a relatively simple
way to add value
Photo: DVO Photos: Living Earth
Photo: DVO Labels: USDA, WSDA, OMRI
Organic certification requirements
• Use of approved feedstocks
• Compost for time and temperature
• Regular testing and recordkeeping
• Specific labeling requirements
Wholesale-retail, packaging matrix
Wholesale Retail
Bulk
Packaged
VALUE
increases
in both
directions
Bags add value
Boxes, buckets, and bottles
Branded package line
Specialty applications
Blower trucks Filter socks
Peat moss replacement
• Extensive WSU research
program, started by Craig
MacConnell at Whatcom
Extension
• Pitched as
green/sustainable, climate-
friendly product for nursery
and horticulture industry
• Commercialization efforts
are continuing.
Photo: DVO Diagram: WSU, Whatcom Extension
Peat moss replacement - research
• Researchers found dairy digester solids had long
fiber length and good air porosity
• Unlike composted products, the fiber had a
spongy quality
• Retained 3X its weight in water
• Contain some NPK and lots of valued trace
elements for good root/plant development
• Consistency is critical for this risk-averse market
Source: Innovation Center for US Dairy, 2013
Potential markets - peat moss replacement
• US horticulture use of peat moss = 6.8 million
tons/year – mostly imported from Canada
• Using digested solids could avoid release of 5.8
million metric tons of CO2-e (1.1 million cars)
• The potential exists to meet this demand from
dairy digesters
Source: Innovation Center for US Dairy, 2013
Commercial peat moss replacement
RePeet™
• Organix, Sunnyside, WA
• Processes digested
dairy manure solids
• Small market currently
Magic Dirt
• Association with DVO
• Refined process
• Developing national
market channels
Specialty products: fiberboard
•Subject of research at
Michigan St Univ
•Patent applications
•Notable qualities and
low cost
•Little commercialization
Photos: Kevin Fowler/AP
Whether [the low cost] is enough to overcome the public's squeamishness
about using a manure byproduct as a building product remains to be seen.
If nobody in industry has an interest, it will die.” Craig Adair, spokesperson
for APA — The Engineered Wood Association.
Specialty products: CowPots
CowPots™
• East Cannan, CT
• Plug-flow digester
Freund Dairy Farm
• Since the late ‘90s
• Now sold nationally
CowPots production
Don’t miss the Dirty Jobs video: www.youtube.com/watch?v=b0vyfgo42AI
CowPots uses and value
50¢/each
Vermicompost
1. Dairy fiber is a desired
media for vermiculture and
vermicomposting; digested
solids are an unknown
2. Earthworm castings/
vermicompost are a valued
media in horticulture,
agriculture and in soil mixes
3. Commercialization efforts
range from small enterprise
to larger, mechanized
facilities
Homegrown worm castings & vermicompost
Earthworm castings & vermicompost
Mixes with earthworm castings
Boutique earthworm castings
Continuous flow vermicompost beds
Commercial vermicompost
Sonoma Valley Worm Farm
• Sonoma County, CA
• Composted dairy manure
Worm Power
• Avon, NY
• Dairy farm-based
$400+ per cubic yard
Biochar
1. Digested solids may have
value for specialty char
2. Added-value: biochars are
valued as green substitutes
for filter media and for carbon
sequestration
3. Commercialization efforts
vary nationally
Photo: DVO
Carbon cycle and biochar
Biochar samples
Biochar specialties
Biochar commercialization
Biochar Solutions Products
Wakefield Agricultural Carbon
$29.99/cf
$17.99/cf $17.99/cf $17.99/cf$14.99/cf$29.99/cf
Future Advances
Green chemicals and bioplastics
Examples:
Polylactic acid (PLA)
Polyhydroxyalkanoate (PHA)
Photo: technologyreview
Conclusions
• Think about how the end value of the digested
solids fits with your project/operation.
• Consider interests and compatibility
• Look for special strengths and assets
• Conduct a feasibility analysis
• Choose from small-, medium- and large-scale
• Look for partnership opportunities
• Build a business plan for the value-add
enterprise
Acknowledgements
This research was supported by funding from USDA National Institute of
Food and Agriculture, Contract #2012-6800219814; Biomass Research
Funds from the Washington State University Agricultural Research
Center; and the Washington State Department of Ecology, Waste 2
Resources Program.
Contact
Jim Jensen Senior Bioenergy and Alt Fuel Specialist
WSU Energy Program
360-956-2083