Proceedings available at: http://www.extension.org/67655 Excessive emissions of ammonia (NH3 ) from animal manure negatively impact the environment with potential to pollute air, soil and water, and produce malodors. The objective of this study was to assess NH3 mitigation from liquid dairy manure (LM) using tubular acid-filled gas-permeable membranes (GPM) in laboratory experiments; and, to evaluate the possibility of scaling up the NH3 mitigation system for use on AFOs.

1. Ammonia Mitigation and Capture as a Liquid
Fertilizer from Manure Using Gas-Permeable
Membrane
Saqib Mukhtar
Professor and Extension Ag. Engineer
Amir M. Samani Majd
PhD Candidate,
Biological & Agricultural Engineering Department, Texas A & M
University System
Waste to Worth Conference, Hyatt Hotel, Denver, CO. April 1-5, 2013

2. Introduction
Animal Manure NH3 Loss into the air
• Loss of a Valuable Nutrient for Plants
• Environmental Issue
• Capturing and Recovery???????
2NH3 + H2SO4  (NH4)2SO2

3. NH3 and NH4
+
• NH3
• NH+
4

4. pH Influences Forms of Ammoniacal N
Ammonium (NH4)
Ammonia (NH3)

5. Ammonia Mitigation Approaches &
Technologies
• Acidic solution-sprayed scrubbers
 Studies underway in our laboratory
• Bio-filters (compost, straw etc.)
• Chemicals like acidified clays and
sodium hydrogen sulfate
• Gas-permeable membrane (GPM)

6. Gas-permeable Membrane
• ePTFE: expanded Polytetrafluoroethylene
(AKA Dental Floss)

7. Methods and Materials
GPM Properties
Type of membrane Used ePTFE
Inside Diameter (cm) 0.672
Outside Diameter (cm) 0.80
Flat Width (cm) 1.25
Wall Thickness (cm) 0.066
Porosity (%) 83
Mean Pore Diameter(μm) 2.401±0.142
Pore size 100X
magnification

8. TAN
Mechanism
NH3 (Gas)
(NH4)2SO4
Capture
Acid-filled GPM
Liquid
manure
Ammonia
(NH4)2SO4

9. Experimental Set-up
Glass wool filled Orifice
Sampling Orifice
Acidic
Solution
(Jar)
Acidic
Solution
(Jar)
Peristalti
c
Pump
LM Chamber
GPM
Sampling
Orifice

10. LM Chambers

11. Liquid Manure Chambers
Experiment
Chamber Inside Dimensions
Depth of LM
in chamber
(cm)
Manure
volume
(L)
Headspace
volume
(L)
Length
(cm)
Width
(cm)
Height
(cm)
Surface area
(cm2
)
1X - 7.7* 23 186 16.2 3 1.3
2 X 19.1 19.1 29 365 16.2 5.9 4.7
4 X 29.2 25.4 29 742 16.2 12 9.5
8X 40.6 35.6 30 1445 16.2 23.4 19.9
*
This entry is radius (cm) of the 1X cylindrical jar.

12. Raw Manure, Collection, Sampling &
Measurements

13. Experimental Set-up
Treatment chamberControl chamber
Acidic flasks
Peristaltic pump

14. Results and Discussion: Feasibility
Concentration of NH3-N in acid and LM
4X Control Chamber
1X Chamber
2X Chamber
pH of LM
pH of LM
NH3
-N in Acid
NH3-N in LM
pH of acid
pH of LM
NH3
-N in Acid
NH3-N in LM
pH of acid

15. Results and Discussion : Feasibility
Concentration of NH3–N in acid and LM
4X Control Chamber
4X Chamber
8X Chamber
pH of LM
NH3-N in Acid
NH3-N in LMpH of acid
pH of LM
NH3
-N in Acid
NH3-N in LMpH of acid
pH of LM
NH3-N in LM

16. Part 2: Diluted H2SO4 solutions
• It is safer for handling and operation
• Lesser contamination of LM if the tube is
ruptured
• Acid solution pH rises faster-Closer to the pH of
common Ammonium Sulfate fertilizer (between
5.5 and 6)
• Diluted acid means less cost

17. Experiments (All 4X chambers)
Nominal pH Time
(days)
Initial pH of the acids (H2SO4 )
Submerged GPM Suspended GPM
Low pH* 18 0.32 0.36
pH 2 7 2.12 2.14
pH 3 7 3.08 3.07
pH4 7 4.11 4.14
pH 5 7 5.42 5.36
*Previous experiment

18. Quick pH increase
pH 5 Experiment

19. NH3 concentrations in different
diluted acidic solutions

20. • Feasibility: The tubular GPM system filled
with acidic solution did extract NH3from LM.
• Efficiency: The 4X experiment was the most
effective, with greatest removal and capture
efficiency.
• Practical Finding: One cm2
surface area of
GPM was needed to treat nearly three cm2
surface area of liquid dairy manure.
Conclusions

21. Conclusions
• As compared to low pH acidic solution, NH3
removal efficiency was reduced considerably due
to a quick increase in pH of all diluted acids.
• Should maintain acid solution at pH 2 or less
during experiments for an efficient and higher
rate of ammonia removal.

22. Submerged GPM system
pH controller and
dosing system
Circulation pump
Pressure gauge and
pressure controller
Solar panels for power supply
to pump and acid dosing system
Acidic solution circulating through
the GPM system
Scaled-Up GPM System

23. Ammonia Concentration in Acidic Solution after 24 Hours of Extraction

24. Average Hourly NH3 Conc. (mg/l) in acidic solution
40 85 190 280
Flow Rate
(ml/min)

25. Acknowledgement
Funding for this study was provided through a
grant 2009-34466-20025 by the United States
Department of Agriculture: National Institute for
Food and Agriculture (UDSA- NIFA)

26. Thanks for your attention.
Questions