Effects on carbon and nitrogen emissions due to swine manure removal for biofuel production.

Methane (CH) and ammonia (NH) 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 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 and CH 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 and increase in NH emissions agrees with a short-term study measured at this location by Lagrangian inverse dispersion analysis. The increase in NH 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, a secondary process for the removal of N in anaerobic waste lagoons. The increase in NH emissions can be partially attributed to the decrease in N production by a proposed NH conversion to N mechanism. This mechanism predicts that a decrease in NH conversion to N increases ammoniacal N pH. Both effects increase NH emissions. It is unknown whether the decrease in NH conversion to N 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.

Changes in swine ammonia emissions associated with improved production management.

Swine manure management and storage have been implicated as major sources of increasing agricultural ammonia (NH3 ) emissions resulting in increased ammonium deposition in North Carolina. This study was conducted to establish how improvements in manure and animal management have affected lagoon nutrient loading and subsequent NH3 emissions determined from measured lagoon chemistry and climate data. Archived lagoon chemistry analyses from 182 farm lagoons (106,000 sample analyses) were used to evaluate trends in lagoon chemical properties. Process and empirical (statistical) NH3 volatilization models were used with the data to calculate changes in NH3 emissions from 2001 through 2018. Lagoon nutrient trends for finisher and sow farms showed that annual averages of nutrients had decreases ranging from 18 to 93%, except for a 41% increase in copper for finisher primary lagoons. Because of reduced nitrogen and pH in the lagoons, a process model of NH3 emissions suggested decreases from primary lagoons of 49 and 25% from finisher and sow farm lagoons, respectively. Empirical (statistical) models predicted even larger relative NH3 decreases (up to 54%).

The effect of biogas ebullition on ammonia emissions from animal manure-processing lagoons.

Various models have been developed to determine ammonia (NH3 ) emissions from animal manure-processing lagoons to enable relatively simple estimations of emissions. These models allow estimation of actual emissions without intensive field measurements or "one-size-fits-all" emission factors. Two mechanisms for lagoon NH3 emissions exist: (a) diffusive gas exchange from the water surface and (b) mass-flow (bubble transport) from NH3 contained within the ebullition gas bubble (as it rises to the surface) produced from anaerobic decomposition of organic matter. The purpose of this research is to determine whether gas ebullition appreciably affects NH3 emissions and therefore should be considered in emissions models. Specifically, NH3 mass-flow emissions were calculated and compared with calculated diffusive NH3 emissions. Mass-flow NH3 emissions were evaluated based on a two-film model, in connection with the acid dissociation constant of ammonium, to predict the degree of NH3 gas saturation within the bubbles. Average daily ammoniacal nitrogen concentration, pH, and measured biological gas production (ebullition) in conjunction with literature values for Henry's law constant were used to calculate emissions from NH3 saturation of ebullition gases. Ebullition enhancement of NH3 surface emissions due to increased turbulence was estimated from average lagoon ebullition rates and literature values of turbulence enhancement. Ebullition enhancement of NH3 surface emissions and ebullition mass-flow NH3 emissions was determined to be <10% and <0.052%, respectively, of total NH3 emissions. Therefore, because ebullition effects are small, they may be neglected when developing process models to estimate NH3 emissions from water surfaces of swine manure processing lagoons.

The effect of biofuel production on swine farm methane and ammonia emissions.

Methane (CH) and ammonia (NH3) are emitted to the atmosphere during anaerobic processing of organic matter, and both gases have detrimental environmental effects. Methane conversion to biofuel production has been suggested to reduce CH4 emissions from animal manure processing systems. The purpose of this research is to evaluate the change in CH4 and NH3 emissions in an animal feeding operation due to biofuel production from the animal manure. Gas emissions were measured from swine farms differing only in their manure-management treatment systems (conventional vs. biofuel). By removing organic matter (i.e., carbon) from the biofuel farms' manure-processing lagoons, average annual CH4 emissions were decreased by 47% compared with the conventional farm. This represents a net 44% decrease in global warming potential (CO2 equivalent) by gases emitted from the biofuel farms compared with conventional farms. However, because of the reduction of methanogenesis and its reduced effect on the chemical conversion of ammonium (NH4+) to dinitrogen (N2) gas, NH3 emissions in the biofuel farms increased by 46% over the conventional farms. These studies show that what is considered an environmentally friendly technology had mixed results and that all components of a system should be studied when making changes to existing systems.

Ammonia emissions from Swine waste lagoons in the Utah great basin.

In animal production systems (poultry, beef, and swine), current production, storage, and disposal techniques present a challenge to manage wastes to minimize the emissions of trace gases within relatively small geographical areas. Physical and chemical parameters were measured on primary and secondary lagoons on three different swine farming systems, three replicates each, in the Central Great Basin of the United States to determine ammonia (NH3) emissions. Nutrient concentrations, lagoon water temperature, and micrometeorological data from these measurements were used with a published process model to calculate emissions. Annual cycling of emissions was determined in relation to climatic factors and wind speed was found the predominating factor when the lagoon temperatures were above about 3 degrees C. Total NH3 emissions increased in the order of smallest to largest: nursery, sow, and finisher farms. However, emissions on an animal basis increased from nursery animals being lowest to sow animals being highest. When emissions were compared to the amount of nitrogen (N) fed to the animals, NH3 emissions from sows were lowest with emissions from finisher animals highest. Ammonia emissions were compared to similar farm production systems in the humid East of the United States and found to be similar for finisher animals but had much lower emissions than comparable humid East sow production. Published estimates of NH3 emissions from lagoons ranged from 36 to 70% of feed input (no error range) compared to our emissions determined from a process model of 9.8% with an estimated range of +/-4%.

Kinetics and Equilibria of the Thiol/Disulfide Exchange Reactions of Somatostatin with Glutathione.

Rate and equilibrium constants are reported for the thiol/disulfide exchange reactions of the peptide hormone somatostatin with glutathione (GSH). GSH reacts with the disulfide bond of somatostatin to form somatostatin-glutathione mixed disulfides (Cys(3)-SH, Cys(14)-SSG and Cys(3)-SSG, Cys(14)-SH), each of which can react with another molecule of GSH to give the reduced dithiol form of somatostatin and GSSG. The mixed disulfides also can undergo intramolecular thiol/disulfide exchange reactions to re-form the disulfide bond of somatostatin or to interconvert to the other mixed disulfide. Analysis of the forward and reverse rate constants indicates that, at physiological concentrations of GSH, the intramolecular thiol/disulfide exchange reactions that re-form the disulfide bond of somatostatin are much faster than reaction of the mixed disulfides with another molecule of GSH, even though the intramolecular reaction involves closure of a 38-membered ring. Thus, even though the disulfide bond of somatostatin is readily cleaved by thiol/disulfide exchange, it is rapidly reformed by intramolecular thiol/disulfide exchange reactions of the somatostatin-glutathione mixed disulfides. By comparison with rate constants reported for analogous reactions of model peptides measured under random coil conditions, it is concluded that disulfide bond formation by intramolecular thiol/disulfide exchange in the somatostatin-glutathione mixed disulfides is not completely random, but rather it is directed to some extent by conformational properties of the mixed disulfides that place the thiol and mixed disulfide groups in close proximity. A reduction potential of -0.221 V was calculated for the disulfide bond of somatostatin from the thiol/disulfide exchange equilibrium constant.