Patent ID: 8637304

Claim:
A method for recovering ammonia from a process of anaerobic digestion, comprising the steps of: (a) anaerobically digesting an organic, nitrogen containing substrate to produce a turbid digested liquid containing ammonia, carbon dioxide, methane and suspended solids; (b) introducing the digested liquid of step (a) to a culture of phototrophic microorganisms capable of consuming CO 2 and bicarbonate in the presence of natural or artificial light, the culture having a surface to volume ratio sufficiently high that light transmission to the culture is adequate for the culture to uptake carbon dioxide and bicarbonate from the digested liquid of step (a) and accumulate biomass, thereby producing a liquid media having an elevated pH; (c) stripping ammonia gas from the liquid media produced in step (b) with a stripping gas that does not include biogas or methane, thereby producing a mixture of water vapor, stripping gas and stripped ammonia gas stream and an ammonia-deficient liquid stream; and (d) condensing the mixture of water vapor, stripping gas and stripped ammonia gas stream in a condenser to form a liquid ammonia condensate, water and cooled stripping gas.