Recent studies have uncovered benefits that resulted from the addition of Zeolite in the anaerobic digestion process.
This document was prepared to provide a compilation of data from world-wide Zeolite studies to be used as an informational resource.
Zeolite Benefits
METHANE PRODUCTION
(Kougias, P.G., et al., 2013) (Kotsopoulos, T.A., et al., 2008) (Meisinger, J.J., et al., 2001) (Montalvo, S., et al., 2012)
• Higher organic matter degradation, resulting in higher methane yield
• 46% increase in methane production (Fig.1)
• 78% methane content of biogas
• 59% volatile solid (VS) conversion to methane
• Higher methane production when Zeolite is present to hold ammonium nitrogen
• Mitigated ammonium levels to balance the C/N ratio for a higher methane yield
MICROORGANISM DEVELOPMENT
(Montalvo, S., et al., 2012) (Kotsopoulos, T.A., et al., 2008)
• Increases the population of anaerobic digesting microorganisms for higher methane yield
• Immobilizes microorganisms on its large surface area to prevent washout and provide a surface for colonization
• Micronutrients and nitrogen are held in the colonization zone
• Hydrolitic and methanogenic microorganisms increased 100 times and the population of hydrolytic microorganisms was 10 times higher
ODOR AND VOC CONTROL
(Meisinger, J.J., et al., 2001) (Montalvo, S., et al., 2012) (Kotsopoulos, T.A., et al., 2008) (Kougias, P.G., et al., 2013)
• Odor and VOC (volatile organic compound) reduction
• The high cation exchange capacity (CEC) of Zeolite exchanges the ammonium nitrogen (NH4+1) into the crystal lattice before it vaporizes to ammonia gas (NH3), the aerosol of odors
DIGESTATE PRODUCTION*
• Odor reduction during field application
• High fertilizer value from nitrogen (ammonium) and potash (potassium) held in the Zeolite lattice
• Higher methane production reduces the carbon content – digestate is lighter and less costly to handle
GROUNDWATER POLLUTION*
• Ammonium is held in theZeolitelattice and doesn’t oxidize into nitrates and nitrites
• Reduction in ground water contamination
Zeolite has the ability to capture ammonium (NH4+1) through its cation exchange capacity (CEC).
Specific microorganisms are needed for each stage in the anaerobic digestion process. Zeolite increases the populations required for each stage. (Montalvo, S., et al., 2012) (Kotsopoulos, T.A., et al., 2008)
How Zeolite Works
Zeolite has the ability to capture ammonium (NH4+1) through its cation exchange capacity (CEC).*
The Zeolite negatively charged and are able to hold positively charged ammonium (NH4+1) and potassium (K+1), which are accessible to microorganisms as needed for growth but not water soluble.
ZEOLITE IN DIGESTATE FERTILIZER
The plant releases hydrogen (H+1) during growth, which exchanges with nitrogen (NH4+1) held in the Zeolite lattice, which is plant accessible but not water soluble.
Available water (H2O) is held in the open pore spaces of the Zeolite near the root zone.
REFERENCES:
Kotsopoulos, T.A., Karamanlis, X., Dotas, D., and Martzopoulos, G.G. 2008. The impact of diferent natural zeolite concentrations on the methane production in thermophilic anaerobic diges-
tion of pig waste. Biosystems Engineering. 99: 105-111.
Kogias, P.G., Fotidis, I.A., Zaganus, I.D., Kotsopoulos, T.A., and Martzopoulos, G.G. 2013. Zeolite and swine inoculum efect on poultry manure biomethanation. Int. Agrophys. 27: 169-173. Meisinger, J.J., Lefcourt, A.M., Van Kessel, J.A.S., and Wilkerson, V. 2001. Managing ammonia emissions from dairy slurry with alum or zeolite or by diet modification. Proc. 2nd Intl. Conf. on Sci. and Policy. 1(S2): 860-865.
Montalvo, S., Guerro, L., Borja, R. Sanchez, E., Milan, Z., Cortes, I., and de la Rubia, A. 2012. Application of natural zeolites in anaerobic digestion processes: A review. Applied Clay Sci. 58: 125-133