Environmental Air Quality, Environmental Data Analysis
Emission of gases, odor, and particulate matters from livestock manure is a major concern because of their potential adverse environmental impacts. For example, ammonia in the air has the potential to: negatively affect animal, human health and environment. Mitigation of ammonia emissions from livestock manure to protect animal and human health, and the environment, in general, is thus an important agenda for livestock producers, engineers, and environmental scientists. Proper understanding of the mechanisms or process of its volatilization from manure is the first step towards designing or formulating appropriate emissions mitigation strategies. This research investigated the effects of suspended solids, anaerobic digestion, and ionic strength on the ammonia (NH3) volatilization mechanism from liquid dairy manure. Experiments were conducted to: (i) assess the role of suspended solids characteristics on ammonia volatilization, (ii) evaluate the impacts of anaerobic digestion on the process governing NH3 v volatilization, and (iii) delineate the influences of suspended solids (SS) and ionic strength (IS) on the ammonia volatilization process from dairy manure. Two key parameters (the ammonia dissociation and the overall mass transfer coefficient (KoL)) that govern ammonia volatilization were evaluated to achieve these objectives. The physical and chemical properties of manure were also evaluated to further elucidate the respective processes. The suspended solids ammoniacal nitrogen adsorption properties did not significantly affect either the ammonium dissociation or the KoL; suggesting that the characteristics of manure suspended solids did not play a significant role in ammonia volatilization from liquid dairy manure. The dissociation of ammonium in anaerobically digested (AD) manure was significantly higher than in the undigested (UD) manure. However, KoL was less in AD manure than in UD manure, while an increase in total ammoniacal nitrogen (TAN) was observed after anaerobic digestion of manure. Overall, increases in ammonium dissociation and TAN after anaerobic digestion indicated higher potential of NH3 volatilization in AD manure. Significant increases in SS concentration and IS were necessary to influence the ammonium dissociation in dairy manure. For all practical purposes, therefore, the individual effects of suspended solids and ionic strength were deemed negligible within the normal ranges of liquid dairy manure characteristics.
I graduated with a PhD from WSU in the area of air quality modeling and currently work with Dr. Dave Huggins in the Department of Crop and Soil Science (WSU, Pullman). I have a diverse academic background with a masters in Statistics (UI), Hydrology (Indian Institute of Technology, India) and Meteorology (Tribhuvan University of Nepal). I have long work experience in area of environmental air quality, environmental analysis and management practices in Nepal, Canada and the United States.
Publications and Presentations:
Koirala, K., Ndegwa, P., Joo, H., Frear, C., Stockle, C., Harrison, J. 2013. Impact of anaerobic digestion of liquid dairy manure on ammonia volatilization process. American Society of Agricultural and Biological Engineers. 56(5): 1959-1966.
Koirala, K., Ndegwa, P., Joo, H., Frear, C., Stockle, C., Harrison, J. 2015. Effects of suspended solids characteristics and concentration on ammonia emission process from liquid dairy manure. American Society of Agricultural and Biological Engineers. 57(2): 661-668.
Koirala, K. Impact of Physical-Chemical Properties on Ammonia Emissions of Dairy Manure. American Geophysical Union, Fall Meeting, Dec. 14-18, 2015, San Franciso, CA.
Koirala, K. Delineating Effects of Ionic Strength and Suspended Solids on Ammonia Volatilization from Dairy Manure Slurry. American Geophysical Union, Fall Meeting, Dec. 15-19, 2014, San Franciso, CA