Ammonia emissions from broiler houses and mitigating technologies

Abstract

In recent years, increased attentions have been given to ammonia (NH3) emissions from poultry due to its environmental and health impacts. NH3 is generated from the chemical decomposition of bird feces by certain bacteria in the litter. NH3 was considered as a precursor to fine particulate matter (PM2.5), and the US Environmental Protection Agency (EPA) has been petitioned to regulate NH3 as a criteria pollutant. Furthermore, NH3 emission represents a significant loss of valuable nitrogen fertilizer. NH3 can be deposited from the atmosphere, if excess nitrogen (N) is deposited, it may impact the ecosystem negatively. Potential environmental issues associated with exceeding N in the environment include nitrate contamination of drinking water; eutrophication of surface water bodies; vegetation or ecosystem changes due to higher concentrations of N; and soil acidification through nitrification and leaching. Several approaches have been suggested and evaluated for mitigating NH3 emissions from concentrated animal feeding operations (CAFOs). Litter amendment can produce hydrogen irons (H+) when it dissolves and inhibit the free NH3 production by converting it to the ammonium (NH4+). The commonly used litter amendments include aluminum sulfate, sodium bisulfate, and ferric sulfate. Acid scrubber can absorb NH3 from exhausted air emitted from CAFOs. The scrubbers usually filled with packing materials and acid solution. Acid solution is sprayed from the top of the reactor. Mass transfer occurs from gas to liquid phase when the air and solution get contact. The vegetative environmental buffer (VEBs) has been used around CAFOs as a best management practice to reduce downwind gas concentration and emissions. Previous studies show VEBs can also mitigate odor and particulate matters. Some studies have been done with those technologies for the NH3 mitigation from poultry operations. However, the data from broiler operations is still limited. In this project, several different NH3 mitigating technologies, include litter amendment, acid scrubber and VEBs, will be tested and evaluated in broiler operations. The data can be used as a reference for future studies and commercial use.