AECO-NAR - Ammonia Recovery

Maximizing the value of digestate

Several technologies claim effective removal of ammonia from digestate. However, all of these technologies consume a lot of energy and only oxidize the ammonia, without creating a valuable product. By removing ammonia, the treated water can be used for:

  • Diluting the substrate to enable more co substrates.
  • Lowering the ammonium concentration of the substrate
  • Improving COD/N ratio of the centrate water

The AECO-NAR is an innovative and stable process which is anticipating today’s challenges in the market and producing ammonium sulphate, to maximize the value of digestate. The market potential for this biobased fertilizer varies per geographical location, but proves to be commercially very attractive.

  • IMG 2774
  • NAR


The AECO-NAR is a proprietary chemical process based on the stripping of ammonia. The process is designed to treat digestate, or manure, and consists of a heat exchanger, a CO2 stripper tank, an ammonia stripper and a scrubber. In order to prevent clogging of the stripping column, pre-treatment of the digestate such as a cloth screen, screw press or centrifuge is required. In the CO2 stripper tank the liquid is heated up and fresh air is injected in to the liquid to strip CO2. A heat exchanger on the effluent flow reduces the heat requirement of the system.


The Nijhuis mission with this next level of ammonia recovery is ‘doing more with less’. The AECO-NAR has a proven ammonia removal efficiency of 80-90%, with the lowest energy consumption. Dilution of the substrate creates a higher biogas production by minimizing toxicity. Less additional co-substrates are required to mix the high ammonia substrates.

Depending on the liquid digestate disposal, the AECO-NAR system will lower the discharge cost. In the case of additional biological treatment no additional carbon source is required, therefore less energy is required, which results in huge savings on OPEX and CAPEX. Finally the stripped ammonia is recovered as ammonium sulphate which requires no oxidation of the ammonia and can be sold as a biobased fertilizer.