Recent studies have uncovered benefits that resulted from the addition of zeolite in the anaerobic digestion process.

This article compiles data from world-wide zeolite studies to be used as an informational resource.

Zeolite benefits

Methane production

  • Higher organic-matter degradation, resulting in higher methane yield
  • 46% increase in methane production
  • 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

  • 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
  • Hydrolytic and methanogenic microorganisms increased up to 100 times, with hydrolytic microorganisms 10 times higher

Odour and VOC control

  • Odour and VOC (volatile organic compound) reduction
  • The high cation exchange capacity (CEC) of zeolite exchanges the ammonium nitrogen (NH4+) into the crystal lattice before it vaporizes to ammonia gas (NH3)

Digestate production

  • Odour 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 the zeolite lattice and does not oxidize into nitrates and nitrites
  • Reduction in groundwater contamination

How zeolite works

Zeolite has the ability to capture ammonium (NH4+) through its cation exchange capacity (CEC).

Zeolites are negatively charged and able to hold positively charged ammonium (NH4+) and potassium (K+), which remain accessible to microorganisms as needed for growth but are not water-soluble.

Zeolite in digestate fertilizer

The plant releases hydrogen (H+) during growth, which exchanges with the nitrogen (NH4+) held in the zeolite lattice — making it plant-accessible but not water-soluble.

Available water (H2O) is held in the open pore spaces of the zeolite near the root zone.