Manure pre-conditioning is necessary to prepare manure as a suitable feedstock for granulation into fertilizer. Pre-conditioning focuses on adjusting the particle size, moisture content, and composition of manure. For wet manures like dairy and hog manure, common pre-conditioning methods include sand removal, anaerobic digestion, coarse fiber removal, and solid/liquid separation. For dry manures like poultry litter, common methods include drying, grinding, and composting. The goal of pre-conditioning is to produce a homogenous feedstock with optimal properties for effective granulation.

1. Pre-conditioning
Manure for Granulation
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2. For centuries, manure has served as a
valuable resource for farmers to put nutrients
and organic matter back into their soil, while
also providing them a means of managing
on-farm waste.

3. As herd sizes continue to grow and farms
must learn to deal with larger amounts of
manure, the granulation of manure into a
fertilizer or soil amendment product is
becoming increasingly popular.

4. Pre-conditioning manure is a critical step
that must take place before manure can
be effectively used as a feedstock in the
granulation process.

5. Why Pre-Conditioning
is Necessary

6. There are many characteristics that
make raw manure an unsuitable
feedstock for granulation.

7. There are many characteristics that
make raw manure an unsuitable
feedstock for granulation.
Pre-conditioning serves to process
manure into a feedstock that will allow
for optimal granulation to occur.
Pre-conditioning focuses on:

8. There are many characteristics that
make raw manure an unsuitable
feedstock for granulation.
Pre-conditioning serves to process
manure into a feedstock that will allow
for optimal granulation to occur.
Pre-conditioning focuses on:
• Particle size distribution

9. There are many characteristics that
make raw manure an unsuitable
feedstock for granulation.
Pre-conditioning serves to process
manure into a feedstock that will allow
for optimal granulation to occur.
Pre-conditioning focuses on:
• Particle size distribution
• Moisture content

10. There are many characteristics that
make raw manure an unsuitable
feedstock for granulation.
Pre-conditioning serves to process
manure into a feedstock that will allow
for optimal granulation to occur.
Pre-conditioning focuses on:
• Particle size distribution
• Moisture content
• Material composition

11. Particle Size Distribution
For granulation to occur, large particles
will need to be removed or ground. A
particle size distribution (PSD) of around
60 mesh is ideal.

12. Moisture Content
The appropriate moisture content is
critical to the success of granulation.
Ideal moisture content for poultry manure
is under 20%, while for hog and dairy
manures, the moisture content should fall
between 60 – 80%, so the material is in a
cake form instead of a slurry.

13. Material Composition
Pre-conditioning also addresses the
composition of the manure.

14. Material Composition
Pre-conditioning also addresses the
composition of the manure.
The material should be examined to
determine if it contains coarse fibers or
bedding, which could inhibit granulation,
as well as dilute the nutrient content.

15. Material Composition
Pre-conditioning also addresses the
composition of the manure.
The material should be examined to
determine if it contains coarse fibers or
bedding, which could inhibit granulation,
as well as dilute the nutrient content.
The material is also analyzed to
determine if it contains any natural
binding agents.

16. Approaches to
Pre-Conditioning

17. The pre-conditioning process varies
considerably from one material to the next.

18. The pre-conditioning process varies
considerably from one material to the next.
Many options are available, with a
combination of methods often being desirable.

19. Pre-Conditioning Wet Feedstock
Common pre-conditioning methods for
wet feedstock such as dairy and hog
manure include:

20. Pre-Conditioning Wet Feedstock
Common pre-conditioning methods for
wet feedstock such as dairy and hog
manure include:
• Sand Removal

21. Pre-Conditioning Wet Feedstock
Common pre-conditioning methods for
wet feedstock such as dairy and hog
manure include:
• Sand Removal
• Anaerobic Digestion

22. Pre-Conditioning Wet Feedstock
Common pre-conditioning methods for
wet feedstock such as dairy and hog
manure include:
• Sand Removal
• Anaerobic Digestion
• Coarse Fiber Removal

23. Pre-Conditioning Wet Feedstock
Common pre-conditioning methods for
wet feedstock such as dairy and hog
manure include:
• Sand Removal
• Anaerobic Digestion
• Coarse Fiber Removal
• Solid/Liquid Separation

24. Sand Removal
In dairy applications where sand is used
as a bedding, sand removal is necessary;
not only is sand abrasive, which can
damage equipment over time, but it also
reduces the effectiveness of granulation
and would be undesirable in a fertilizer
product.

25. Sand Removal
In dairy applications where sand is used
as a bedding, sand removal is necessary;
not only is sand abrasive, which can
damage equipment over time, but it also
reduces the effectiveness of granulation
and would be undesirable in a fertilizer
product.
Sand can also fill up digesters if not
removed.

26. A sand separation system is used to
remove sand from manure. This is
typically a combination of steps that
work to wash the material and run it
through an inclined screw, hydrocyclone,
or sand lane to separate out the sand.

27. Anaerobic Digestion
Anaerobic digestion is a biological
process that breaks down material in the
absence of oxygen.

28. Anaerobic Digestion
Anaerobic digestion is a biological
process that breaks down material in the
absence of oxygen.
This process homogenizes and stabilizes
the manure in order to prepare it for
solid/liquid separation and nutrient
capture.

29. The slurry material resulting from
anaerobic digestion is reduced in odor
and pathogens.

30. The slurry material resulting from
anaerobic digestion is reduced in odor
and pathogens.
Anaerobic digestion also produces a
biogas which can be converted into a
usable fuel source to make electricity, be
used on-farm, or sold back to the
energy grid.

31. Coarse Fiber Removal
Coarse fibers must also be removed prior
to granulation. This step is necessary to
remove any bedding or straw particles
that would impede granulation or create
a weak pellet product.

32. Solid/Liquid Separation
When moisture can be freely pressed out,
solid/liquid separation (with nutrient
capture) is required.

33. Solid/Liquid Separation
When moisture can be freely pressed out,
solid/liquid separation (with nutrient
capture) is required.
Solid/liquid separation yields a
concentrated cake material ideal for use
in a fertilizer product because of its rich
nutrient content.

34. Solid/liquid separation can be carried out
using a variety of methods, with
techniques combining mechanical,
gravity, and chemical action.

35. A common pre-conditioning flow for wet feedstock:

36. Pre-conditioning Dry Feedstock
Dry feedstock is generally a poultry
manure, poultry litter, compost, or other
type of similar material.

37. Pre-conditioning Dry Feedstock
Dry feedstock is generally a poultry
manure, poultry litter, compost, or other
type of similar material.
Here again, many methods are available
for pre-conditioning, with a combination
of methods often being desirable:

38. Pre-conditioning Dry Feedstock
Dry feedstock is generally a poultry
manure, poultry litter, compost, or other
type of similar material.
Here again, many methods are available
for pre-conditioning, with a combination
of methods often being desirable:
• Drying

39. Pre-conditioning Dry Feedstock
Dry feedstock is generally a poultry
manure, poultry litter, compost, or other
type of similar material.
Here again, many methods are available
for pre-conditioning, with a combination
of methods often being desirable:
• Drying
• Grinding

40. Pre-conditioning Dry Feedstock
Dry feedstock is generally a poultry
manure, poultry litter, compost, or other
type of similar material.
Here again, many methods are available
for pre-conditioning, with a combination
of methods often being desirable:
• Drying
• Grinding
• Composting

41. Drying
A pre-drying step is sometimes necessary
if the moisture content of the material is
too high. This is especially true when a
grinding step is required, because a
material that is too wet would clog the
equipment.

42. Drying
A pre-drying step is sometimes necessary
if the moisture content of the material is
too high. This is especially true when a
grinding step is required, because a
material that is too wet would clog the
equipment.
Drying can be carried out using a variety
of equipment, or through back mixing – a
process where dried product is mixed
with wet feedstock to reduce the
moisture content.

43. Grinding
Grinding is necessary when the material
contains large particles, as these would
inhibit effective granulation.

44. Grinding
Grinding is necessary when the material
contains large particles, as these would
inhibit effective granulation.
This is commonly carried out using a
hammer mill.

45. Composting
Anaerobic digestion is often not an
option for dry feedstock, because it
requires a pumpable slurry. For this
reason, composting is often used with dry
feedstock materials to homogenize the
material and break it down prior to
granulation.

46. While composting can be used for both
wet and dry feedstock, it is typically only
seen with dry, because wet feedstock
contains too much moisture to be
efficiently composted, and would likely
require a lot of bulking agents, which
would dilute the overall nutrient content.

47. A common pre-conditioning flow for dry feedstock:

48. Conclusion
Pre-conditioning manure prior to granulation is
a critical component in the success of the
process and end product.
Depending on the feedstock characteristics, a
variety of options are available, with a
combination of methods often producing the
desired results.

49. has been a leader in transforming wastes into
value-added products since 1951. In addition to
feasibility testing, process design, and custom
equipment, we offer complete systems for the
granulation of manure into a premium product.

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