Livestock confinement facilities generate large amounts of animal waste that can create serious environmental and human health concerns. For example, animal waste constituents such as organic matter, nitrogen, phosphorus, pathogens and metals can degrade water quality, air quality, and adversely impact human health. Organic matter, for example, contains a high amount of biodegradable organics and when discharged to surface waters will compete for, and deplete the limited amount of dissolved oxygen available, causing fish to die and other undesirable impacts. Similarly, nutrient loading from nitrogen and phosphorus can lead to eutrophication of surface waters.
Methods, systems, and apparatuses for anaerobic digestion of waste fibrous material and the recovery of nutrients are provided. Methods, systems, and apparatuses disclosed herein provide mechanisms to release dissolved gases from anaerobic digester effluent. Methods, systems and apparatuses disclosed herein can recover one or more nutrients from anaerobic digested effluent using a range of temperatures, aeration rates, aeration times, pH ranges, and settling times.