Process and device for the removal of ammonia from wastewater and the recovery of valuable material

摘要

The ammonia source for increasing the pH to ≥ ca. 5.5 of ammonium-sulfate or -phosphate recovered in a process for removal of ammonium (NH4) from waste water is the ammonia (NH3)-loaded gas stream from the first separation column used in the process. Ammonium (NH4) removal from waste water (especially from a clarification plant) with accompanying recovery of useful materials comprises: (i) transferring the NH4 from the aqueous phase into an ammonia (NH3)-loaded gas stream using a first separation column (6); (ii) passing the gas stream to a second separation column (17) with addition of sulfuric or phosphoric acid to recover ammonium sulfate (AMS) or ammonium phosphate (AMP) with pH ca. 2.0-3.8; and (iii) increasing the pH of the AMS or AMP to ≥ ca. 5.5 by addition of NH3, the NH3 being obtained from the NH3-loaded gas stream from the first separation column (6). An Independent claim is included for apparatus for the process comprising three separation columns (6, 17 and 23), column (6) transferring the NH4 from the aqueous phase into an ammonia (NH3)-loaded gas stream, column (17) having a sump (18) connected to the top (5) of column (6) to allow partial introduction of the NH3-loaded gas stream and also a top inlet (20) for addition of sulfuric or phosphoric acid and column (23) processing the NH3-loaded gas stream to raise the pH of the AMS or AMP.