Ammonia emissions from pig slurries: evaluation of acidification and the use of additives in reducing losses

Ammonia emissions during storage of pig slurry were followed through laboratory experiments to evaluate several chemical and commercial additives on decreasing losses. A series of cylindrical columns of 5 cm depth and 10 cm diameter were used to simulate a column of slurry stored in a pit. Each glass volatilization chamber contained 300 g of raw or chemically treated pig slurry. During the experiment the ammonia-charged air was drawn out of the lid and entered the chemical trap (0.1 N sulphuric acid or 4% boric acid) at a flow rate of 5 litres/min (about 8-10 exchange volumes/min). Five commercial chemical additives (Stalosan, De-odorase, odorless, biosuper and NX23) were used at three Fates (low, recommended and high) to evaluate their performances on ammonia losses. Strong acids and calcium chloride were evaluated concurrently to the pit additives. Two commercials additives from the five tested had an effect on reducing ammonia losses. The emissions from the slurries treated with these two additives were reduced by approximately 40% to 50% in comparison to emissions from the untreated slurries. Both the addition of calcium chloride and the acidification of slurries to pH 6 gave an 85% reduction in the ammonia lost. Results obtained from those laboratory experiments were confirmed in field trials using a wind tunnel system.