1. Benefits of Using Liquid-Solid
Separation with Manure
Treatment Lagoons
John P. Chastain, Ph.D., Professor and Extension Agricultural
Engineer, School of Agricultural, Forest, and Environmental
Sciences, Clemson University
Jeffery Porter, Environmental Engineer, USDA-NRCS Manure
Management Team
Waste to Worth Conference, Denver, Colorado
Grand Hyatt Hotel • April 1-5, 2013

2. Purpose
 Define a manure treatment lagoon and how it
is sized.
 Summarize the benefits of using liquid-solid
separation prior to lagoon treatment.

3. Liquid-Solid Separation Options
1. Separation based on particle size – screens &
presses.
2. Separation based on density of the manure –
gravity & cyclones
3. Can provide solid removal efficiencies in the
range of 10% to 60% depending on species
and manure solids content.

4. Some simple screen type separators

5. Some types of press separators

6. Combination of an in-channel flighted conveyor screen
and a small screw press to treat liquid swine manure
Screw Press

7. Liquid-solid separator that employs three
techniques: fine stationary incline screen (0.020
in), screw press, and an inclined flighted
conveyor screen (courtesy of US FARM
Systems, Tulare, CA).

8. Liquid-Solid Separation by Settling

9. Since the settled solids are slurry they can be
used to load a press if dry solids are needed.

10. Chemicals can be used to remove 70%
to 90% of the solids and P for most
methods of liquid-solid separation
- Need proper dose
- Need proper mixing
- Need proper dilution
- Need $$$

11. Benefits of Liquid-Solid Separation for
Manure Storages – not for recycle systems
This is not a lagoon.

12. Benefits of Liquid-Solid Separation for
Storages
 Remove large particles to reduce energy and
time needed for agitation and pumping
 Reduce manure storage volume by up to 20%
if TS removal is on the order of 40%.
 Remove large particles that could cause
clogging of pipes and nozzles.

13. Manure Treatment Lagoons Are Different
From Storages– best for recycle systems

14. Lagoon Sizing
 Lagoon Volume = (Manure Volume +
Treatment Volume + Sludge Storage Volume)
 On top of these volumes add DEPTHS for
Net Rain (P+R), 25 year – 24 hr storm +
minimum of 12” of freeboard.
 These depths are required for any manure
storage.

15. Typical Lagoon System

16. Well treated recycled lagoon water needed
for manure removal.
 High loading rates = strong recycle water for
flush and pit-recharge buildings.
 Need well treated lagoon water to make recycle
flush and pit-recharge buildings function
properly.
 Maximum loading for recycle should be based on
ASABE Standard.

17. Use of a mechanical separator (MS) to reduce
loading on lagoon

18. Enhancing solids and nutrient removal by using
chemicals slows the system down in this configuration.

19. Gravity settling can be used to make high-rate
mechanical separation easier – also reduces chemical
costs.

20. Add a settling basin or pond before the
lagoon – basins drain dry, ponds do not.

21. Can use chemicals to enhance removal of solids and
plant nutrients for a settling basin or pond.

22. Manure Storage Volume
 Will include all manure, wasted water, and
other solids added to manure per day
(bedding and wasted feed)
 Typically use a storage period ranging from
180 days in warm southern climates to 365
days in cold climates (e.g. Midwest)
 Liquid-solid separation can reduce this
volume by 10% to 25%. Best to be
conservative.

23. Treatment Volume
 Depends on VS loading rate , LR = lb
VS/1000ft3/day.
 TV (ft3) = 1000 (lb VS/day / LR)
 Design loading rate depends on the climate.
 Larger loading rates can be used in warm
climates than in cold climates (ANSI/ASAE
EP403.4, ASABE, 2011)

24. Variation of LR With Climate
(ANSI/ASAE EP403.4, ASABE, 2011)
Loading Rate, lb
Location VS/1000ft3/day
Southern Minnesota (Cold) 3.0
Iowa 3.5
Kansas 4.0
North Carolina 4.5
South Carolina & Georgia 5.0
Central Texas 5.5
Central Florida (Hot) 6.0

25. VS Removal Reduces TV, ft3 / 1000 lb of live
animal weight, Finishing Swine (5.01 lb VS/1000 lb)
Loading Rate VS Removed by Liquid-Solid Separation
lb VS/1000 ft3-d 0% 20% 40% 60% 80%
3.0, MN 1668 1335 1001 667.3 333.7
3.5, IA 1430 1144 858.0 572.0 286.0
4.0, KS 1251 1001 750.8 500.5 250.3
4.5, NC 1112 889.8 667.3 444.9 222.4
5.0, SC 1001 800.8 600.6 400.4 200.2
5.5, TX 910.0 728.0 546.0 364.0 182.0
6.0, FL 834.2 667.3 500.5 333.7 166.8

26. VS Removal Reduces TV, ft3 / 1000 lb of live
animal weight, Dairy Cows (11.8 lb VS/1000 lb)
Loading Rate VS Removed by Liquid-Solid Separation
lb VS/1000 ft3-d 0% 20% 40% 60% 80%
3.0, MN 3936 3149 2362 1574 787.2
3.5, IA 3374 2699 2024 1349 674.7
4.0, KS 2952 2362 1771 1181 590.4
4.5, NC 2624 2099 1574 1050 524.8
5.0, SC 2362 1889 1417 944.6 472.3
5.5, TX 2147 1718 1288 858.8 429.4
6.0, FL 1968 1574 1181 787.2 393.6

27. Sludge Storage Volume, ft3/1000lb /year
(ANSI/ASAE EP403.4, ASABE, 2011)
 Depends on TS loading rate , MTS = lb
TS added per year.
 Sludge accumulation rates:
 Swine = 0.0219 ft3/lb TS Added
 Dairy = 0.0729 ft3/lb TS Added

28. Liquid-solid separation will reduce sludge build
up in a treatment lagoon – Critical for dairy!
Swine Dairy
TS Removed By Sludge Volume Sludge Volume
Separator Per Year Per Year
0% 52.0 ft3/AU 383.2 ft3/AU
20% 41.6 306.5
40% 31.2 229.9
60% 20.8 153.3
80% 10.4 76.63
Solids Production: Swine = 6.5 lb TS/AU/day, Dairy = 14.4lb/AU/day

29. Odor Reduction?
 Research has shown that most of the odor
comes from particles that are smaller than
0.0098” (0.25mm).
 Must have high-rate separation to greatly
reduce odor production from liquid manure.
 However lower VS loading rates have been
shown to reduce frequency of odor from a
lagoon.

30. Effect of VS Loading Rate on Odor
Frequency (adapted from Humenik, et al. 1981)

31. Summary
 Liquid-solid separation can be used to
significantly reduce treatment and sludge
storage volumes.
 Allows use of smaller structures to save
money.
 Allows more economical use of lower loading
rates to improve recycle water quality.
 Can help reduce ammonia and odor
production

32. Summary (2)
 Can allow use of anaerobic treatment lagoons
in colder climates.
 Can be used to remove a portion of VS and
Organic-N that would breakdown in the
lagoon to yield methane, ammonia, and
carbon dioxide.
 Reduces cost of sludge management to
maintain lagoon function.

33. Agricultural Mechanization &
Business
School of Agricultural, Forest, and
Environmental Sciences
Contact:
Christi Leard
864.656.3250