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Effects on Carbon and Nitrogen Emissions due to Swine Manure Removal for Biofuel Production
Author(s) -
Weaver Kim H.,
Harper Lowry A.,
Brown Sarah M.
Publication year - 2012
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2011.0374
Subject(s) - methanogenesis , manure , biofuel , environmental science , ammonia , ammoniacal nitrogen , methane , environmental engineering , biogas , manure management , greenhouse gas , environmental chemistry , anaerobic digestion , chemistry , pulp and paper industry , waste management , wastewater , agronomy , ecology , biology , engineering , organic chemistry
Methane (CH 4 ) and ammonia (NH 3 ) are emitted from swine‐manure processing lagoons, contributing to global climate change and reducing air quality. Manure diverted to biofuel production is proposed as a means to reduce CH 4 emissions. At a swine confined animal feeding operation in the U.S. Central Great Basin, animal manure was diverted from 12 farms to a biofuel facility and converted to methanol. Ammonia emissions were determined using the De Visscher Model from measured data of dissolved lagoon ammoniacal N concentrations, pH, temperature, and wind speed at the lagoon sites. Other lagoon gas emissions were measured with subsurface gas collection devices and gas chromatography analysis. During 2 yr of study, CO 2 and CH 4 emissions from the primary lagoons decreased 11 and 12%, respectfully, as a result of the biofuel process, compared with concurrently measured control lagoon emissions. Ammonia emissions increased 47% compared with control lagoons. The reduction of CH 4 and increase in NH 3 emissions agrees with a short‐term study measured at this location by Lagrangian inverse dispersion analysis. The increase in NH 3 emissions was primarily due to an increase in lagoon solution pH attributable to decreased methanogenesis. Also observed due to biofuel production was a 20% decrease in conversion of total ammoniacal N to N 2 , a secondary process for the removal of N in anaerobic waste lagoons. The increase in NH 3 emissions can be partially attributed to the decrease in N 2 production by a proposed NH 4 + conversion to N 2 mechanism. This mechanism predicts that a decrease in NH 4 + conversion to N 2 increases ammoniacal N pH. Both effects increase NH 3 emissions. It is unknown whether the decrease in NH 4 + conversion to N 2 is a direct or physical result of the decrease in methanogenesis. Procedures and practices intended to reduce emissions of one pollutant can have an unintended consequence on the emissions of another pollutant.