Assessments of Mitigation Techniques on Ammonia Emissions from Animal Slurries and Digestate during Storage

One of the environmental concerns relates to ammonia emissions from animal manure. Their effect include acidification, eutrophication and secondary particle (PM2.5) formation. Ammonia volatilize from manure in housing, during storage and during spreading. To reduce ammonia emissions from manure suitable techniques should be identified. The purpose of this study is to carry out the potential measurement of ammonia emissions from animal manure and evaluate its reduction using various mitigation techniques. The experiment was carried out at a controlled temperature of 20^0C using six different slurries of three different types: pig, cow and digestate. The slurries were analyzed for total Kjeldhal nitrogen, ammoniacal nitrogen (TAN) and pH, at the beginning of the experiment, according to standard methods (APHA, 2005). Each slurry was tested in duplicate measuring ammonia emission from a 1 L container with acid traps and comparing the emissions of the raw slurries and with the following mitigation techniques: oil, clay, sawdust, straw and concentrated sulfuric acid of 98%. The results demonstrated that the more effective techniques are the acidification at a pH lower than 5.5 and addition of oil to create a barrier to volatilization. The reduction obtained with these techniques compared to the raw slurries were higher than 80% reaching in some case, values over 95%. The mitigations effect for cow slurries was lower than for pig slurries and digestates.