Ammonium sulphate is the filtered blowdown water from chemical air washers. This liquid fertilizer can best be compared to CAN (calcium ammonium nitrate) or sulfuric ammonia, commercially available as fertilizer, with the difference that the ammonium sulphate is liquid and contains less nitrogen.
The ammonium sulphate complies with the French standard NF U 42-001.
Ammonium sulphate can perfectly meet the nitrogen requirement and especially the sulphur requirements of crops (e.g. cabbage, onions,
celery, leeks, grains, sugar beets, corn, ...).