Ammonia Mitigation and Capture as a Liquid Fertilizer from Manure Using Gas-Permeable

Membrane

Saqib MukhtarProfessor and Extension Ag. Engineer

Amir M. Samani MajdPhD Candidate,

Biological & Agricultural Engineering Department, Texas A & M University System

 Waste to Worth Conference, Hyatt Hotel, Denver, CO. April 1-5, 2013

IntroductionAnimal Manure NH3 Loss into the air

• Loss of a Valuable Nutrient for Plants

• Environmental Issue

• Capturing and Recovery???????

2NH3 + H2SO4 (NH4)2SO2

NH3 and NH4+

• NH3

• NH+4

pH Influences Forms of Ammoniacal N

Ammonium (NH4)

Ammonia (NH3)

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)

Gas-permeable Membrane

• ePTFE: expanded Polytetrafluoroethylene

(AKA Dental Floss)

Methods and MaterialsGPM Properties

Type of membrane Used ePTFE

Inside Diameter (cm) 0.672Outside Diameter (cm) 0.80Flat Width (cm) 1.25Wall Thickness (cm) 0.066Porosity (%) 83

Mean Pore Diameter(μm) 2.401±0.142Pore size 100X magnification

TAN

Mechanism

NH3 (Gas)

(NH4)2SO4

Capture

Acid-filled GPM

Liquid manure

Ammonia

(NH4)2SO4

Experimental Set-upGlass wool filled Orifice 

Sampling Orifice 

Acidic Solution (Jar)

Acidic Solution (Jar)

PeristalticPump

LM Chamber

GPM

Sampling Orifice

LM Chambers

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.

Raw Manure, Collection, Sampling & Measurements

Experimental Set-up

Treatment chamberControl chamber

Acidic flasks

Peristaltic pump

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

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 LM

pH of acid

pH of LM

NH3-N in LM

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

Experiments (All 4X chambers)

Nominal pH Time (days)

Initial pH of the acids (H2SO4 )

Submerged GPM Suspended GPM

Low pH* 18 0.32 0.36pH 2 7 2.12 2.14pH 3 7 3.08 3.07pH4 7 4.11 4.14pH 5 7 5.42 5.36

*Previous experiment

Quick pH increasepH 5 Experiment

NH3 concentrations in different diluted acidic solutions

• Feasibility: The tubular GPM system filled with acidic solution did extract NH3 from 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

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.

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

Ammonia Concentration in Acidic Solution after 24 Hours of Extraction

Average Hourly NH3 Conc. (mg/l) in acidic solution

40 85 190 280 Flow Rate (ml/min)

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)

Thanks for your attention.

Questions