Ammonia stripping/scrubbing

Ammonia from the liquid fraction of manure or digestate can be recovered by sending air or steam through the liquid fraction. The proportion of ammonia in the gaseous phase can be increased by shifting the equilibrium NH3: NH4+ to the gaseous NH3. This can be done by increasing the temperature and / or the pH.
The stripping gas, which is saturated with ammonia, is then brought into contact with a strongly acidic solution (usually sulfuric acid, H2SO4). When sulfuric acid is used to capture ammonia, an ammonium sulphate solution is formed. Optionally, the more expensive nitric acid (HNO3) can also be used to capture ammonia, which will produce ammonium nitrate, which is more interesting for fertilization.

This technique is already used on waste water in Flanders but is not widely introduced for manure and digestate.