Ammonia elimination from beet sugar factory condensate streams by a stripping-reabsorption system

Ammonia formed during the purification and evaporation stages is one of the main source of odours in a beet sugar factory. As a result of legislation, the condensates produced must be treated before discharge. In order to remove the ammonia present in the condensates, a pilot plant was designed for the treatment of 1 m(3) . h(-1) of the liquid stream, consisting of two columns packed with Raschig rings (1 inch). In the first column (stripper), the ammonia was removed from the condensate stream, at a suitable pH value and temperature, by means of a countercurrent air stream. In the second column (absorber), the air enriched with ammonia was treated using a chemical absorption reaction and then recirculated to the stripping tower. The most satisfactory operating conditions used in the design of the stripping plant were obtained previously from laboratory experiments: temperature of 70 degrees C, pH greater than or equal to 11, liquid/gas ratio: 1:800 and 96% efficiency.