Chemical methods for the remediation of ammonia in poultry rearing facilities: A review

Possible chemical methods for the treatment of ammonia in the air of livestock holding facilities, with particular focus on poultry production, are reviewed in the context of eliminating ammonia by oxidation to elemental nitrogen. Gas phase catalytic oxidation processes are incompatible with the needs of the poultry industry on grounds of both capital cost and energy intensiveness. Most chemical oxidants convert ammonia principally to nitrate rather than N 2 . So-called advanced oxidation processes are unsuited to ammonia oxidation because the hydroxyl radicals that characterize these oxidations react poorly with both NH 3 and NH 4 + . One promising option is electrochemical oxidation, which does not require the purchase of stoichiometric amounts of chemical oxidants. Among possible electrochemical methods, we favour electrochemical hypochlorination, whereby the denitrification of ammonia to elemental nitrogen is mediated by hypochlorous acid, which is formed reversibly from chloride ion. This technique is compatible with currently available scrubbing technology, with the modification of using acidic brine as the scrubbing solution. Because electrochemical hypochlorination can be applied without costly and complicated pH adjustment of the scrubbed solution with chemical additives, it constitutes an example of best available technology.