Process & contact
Nitrogen recovery from ammonia rich stream such as fresh manure/slurry or digestate (unseparated or liquid fraction)
Solution of ammonium sulphate (AS) or ammonium nitrate (AN)
Concentration is up to 75 g/l for AS and 150 g/l for AN (50:50 NH4:NO3).
The mineral nitrogen compound solution can be used as a commodity chemical or as a mineral N fertiliser.
Ammonia is removed from the liquid to a gaseous stream pH increase achieved heat (60-70°C) and by CO2 stripping and/or chemical dosing pressure, then recovered by contact with sulphuric or nitric acid.
Ammonia removal can facilitate use of manure or digestate (lower N content), avoid atmospheric ammonia losses, and improve aerobic treatment or biogas production (if applied upstream of treatment or digester).
Around 50% - 80% of ammonia in substrate is recovered.
Contaminant levels in the recovered N product are not analysed to date.
Three full scale plants are operating since 2021:
- Van Alphen – Axel NL(30 000 t/y ww digestate)
- Bio-gas Veendam – Veendam NL (30 000 t/y ww digestate)
- Green Create W2V Kent – Kent UK (170 000 t/y ww digestate).
Containerised installations are available treating up to 43 000 t/y ww.