Ammonia stripping from condensate and spent carbonatation gas

Recovery of ammonia, produced in the course of sugar manufacturing, is no longer just desirable, but an urgent necessity. Effluent and emission regulations force sugar factories to adopt expensive procedures to comply with specified ammonia limits, The solutions to the problem so far devised in Italy only cover emissions, and the methods of eliminating ammonia from condensates and emissions described by German authors are not applicable in the Italian sugar industry. The procedure described in this article, which has been employed in the Jesi factory since the 1996 campaign, involves the treatment of condensate in cation exchangers and of spent carbonatation gas in a jet scrubber. The run-off produced in regenerating the ion exchangers, which contains ammonium sulfate in addition to excess sulfuric acid, is pumped to the jet scrubber which strips out the ammonia. The treated condensate is used as extraction feed water. Employment of two columns, with 8 m(3) of strongly acidic cation exchange resin each, produced sufficient sulfuric acid to reduce the ammonia content of the spent gas below the required limit. Compared with the stripping method used hitherto, the combination of cation exchanger and jet scrubber proved more cost-effective, the more so as ammonia-free condensate becomes available for technological purposes.