During anaerobic digestion, nutrients contained in the organic matter are conserved and mineralized to more soluble and biologically available forms, providing a more predictable biofertilizer.  By recycling the treated effluents back to productive agricultural lands, at appropriate rates, the crops benefit from the presence of these important plant nutrients.  Where insufficient cropland is available, other nutrient recovery technologies may be employed to reduce the nutrient content of the digested wastewater.

Three Common Biogas Residues

Microbial solids (sludge), Fiber, & Wastewater

Resources

Harris, W.G., A.C. Wilkie, X. Cao and R. Sirengo. Bench-scale recovery of phosphorus from flushed dairy manure wastewater. Bioresource Technology, 99(8):3036-3043 (2008). https://doi.org/10.1016/j.biortech.2007.06.065

Lincoln, E.P., A.C. Wilkie and B.T French. Cyanobacterial process for renovating dairy wastewater. Biomass and Bioenergy, 10(1):63-68 (1996). https://doi.org/10.1016/0961-9534(95)00055-0

Sooknarh, R.D. and A.C. Wilkie. Nutrient removal by floating aquatic macrophytes cultured in anaerobically digested flushed dairy manure wastewater. Ecological Engineering, 22(1):27-42 (2004). https://doi.org/10.1016/j.ecoleng.2004.01.004

Wilkie, A.C. and W.W. Mulbry. Recovery of diary manure nutrients by benthic freshwater algae. Bioresource Technology, 84(1):81-91 (2002). https://doi.org/10.1016/S0960-8524(02)00003-2