Recovery of ammonia from carbonatation vent gases

The emission of ammonia in the atmospheric emissions derived from working processes constitutes a rather common problem for the sugar industry. For an Italian factory slicing 450 t/h of sugar beet, the ammonia emissions are estimated at approximately 84 kg/ h; of these approximately 55 kg/h are directly emitted into the atmosphere and 29 kg/h into the waste water collection tanks. In order to remove ammonia from carbonatation vent gases, the decision was made to install a water jet scrubber. An acidic solution of sulfuric acid was used as absorbent. The scrubber was installed in a plant handling 12,000 t/day of sugar beet. The data regarding ammonia scrubbing are provided as a function of washing solution acidity. The best results were obtained with pH values around 3.4-3.5 yielding 74-75% removal. The ammonium sulfate solution is, in principle, a waste product and some possible uses, or means of exploitation other than disposal are discussed.