Modeling nitrogen nutrient loss and ammonia emissions from animal farms

Author institution (Zhao): Department of Food, Agricultural, and Biological Engineering, The Ohio State Universit

Production of Ammonium Sulfate Fertilizer Using Acid Spray Wet Scrubbers

Significant nitrogen loss as ammonia emissions from animal facilities is resulting in severe environmental problems while supply of nitrogen (N) fertilizer for crop production becomes a challenge due to the fact that commercial nitrogen productions use unsustainable natural gas as the primary feedstock. This study investigates an alternative method for production of ammonium sulfate (AS) fertilizer using acid spray wet scrubbers. Ammonium sulfate is produced as a byproduct of mitigation of ammonia emissions from animal production facilities using acid spray wet scrubbers, in which dilute sulfuric acid (H2SO4) reacts with ammonia-laden air from exhaust fans of animal facilities. Effluents of two scrubbers: one installed at a deep-pit swine facility and one at a commercial poultry manure composting facility, were analyzed for their characteristics and AS fertilizer contents. Short-term batch operation of the swine and poultry scrubbers resulted in effluents with maximum AS concentrations of 18.7% (w/v) and 36.3%, respectively. Aside from AS, other essential elemental contents were also found in the scrubber effluent, such as Na, Mg, Al, P, K, Ca, Fe, and Mn. Production rates of AS were calculated based on nitrogen mass balance analyses of air streams and were compared to actual production observed during the scrubber operations. The maximum AS production rates were estimated as 1.53 kg d-1 and 60.96 kg d-1 for swine and poultry operations, respectively.  However, only 18% and 32% were obtained from actual operation. This discrepancy is primarily due to errors in the estimation and liquid losses from leakage, salt precipitation inside the scrubber during short-term batch operation, and air entrainment. The estimated production costs for both swine and poultry scrubber operations at the estimated production rates are $5.74 and$1.46 per kg AS, respectively. Further study to improve the scrubber design to eliminate leaks and to operate continuously is needed to increase AS yield and profitability of the process

Modeling Wireless Signal Transmission Performance Path Loss for ZigBee Communication Protocol in Residential Houses

Low-cost and high performance wireless technologies make it a reality to develop a wireless HVAC control system for multi-zone environmental control in residential houses to improve individual comfort and reduce energy consumption. The lack of understanding on signal transmission performance of wireless sensor network in residential houses limited the application of wireless sensor networks, especially the new ZigBee protocol. This paper is to establish path loss models for predicting wireless data transmission performance in residential houses for ZigBee protocol. Factors affecting the wireless data transmission in residential indoor environment include free space separation, walls, floors, and wireless device inteference. Effects of these factors on the path loss in residential indoor environment were evaluated through empirical testing using received signal strength indicator (RSSI) value measured by commercial ZigBee modules and an embedded microcontroller-based data acquisition system. The model for the effects of walls on the same floor was able to predict 73.6% of the system variability. The measured RSSI data were made versus 1mW transmission source and therefore the RSSI-based path loss models were able to accurately predict the performance of wireless signal of stronger or weaker power transmission systems

Ammonia Emissions from a Commercial Poultry Manure Composting Facility

Composting is an effective waste management technology for converting animal wastes into valuable organic fertilizer. However, air emissions from composting, especially ammonia (NH3) emission, reduces the nitrogen fertilizer value of the compost and greatly impacts the environment. Ammonia emission from commercial composting facilities is not well understood and is limiting mitigation or recovery of NH3 emission from these facilities. The goal of this study was to determine the NH3 emission from a poultry manure compost facility and its temporal variations for development of mitigation strategies. A commercial composting facility was chosen for this study. Manure was supplied from four adjacent manure-belt layer barns. The composting building was tunnel ventilated by four 122-cm exhaust fans. Ammonia concentration at the building inlet and the fan exhausts was monitored quasi-continuously for one month in each of the four seasons using a MSA photoacoustic NH3 analyzer. Air temperature and humidity at the exhausts were monitored using a HOBO temperature and RH sensor and data logger. The exhaust fans were calibrated using FANS units to quantify the ventilation rate of the building. Ammonia emission rate was calculated according to the NH3 concentrations and building ventilation rate. The daily average NH3 concentrations at the exhaust of the compost house varied from 123 ppm in spring to 167 ppm in summer. The daily average NH3 emission rates of the compost facility varied from 231 kg/d in spring to 315 kg/d in summer. Strong diurnal variations exist in spring and summer seasons. Daytime NH3 emission is significantly higher than that of nighttime. The annual NH3 emission rate of the composting facility was estimated as 96,143 kg. The emission factors were calculated as 13±1.3 kg/ton · d and 0.32 ±0.14 g/d · hen. The results of this study will contribute to the development of NH3 emission mitigation technologies and management practices

Estimation of Ammonia Emission from Manure Belt Poultry Layer Houses Using an Alternative Mass Balance Method

Ammonia (NH3) emissions from poultry animal feeding operations (AFOs) have caused health and environmental concerns. Current NH3 emission measurement methods are accurate and reliable but also time-consuming, expensive, and impractical for most animal facilities. In this study, an alternative mass balance method was developed to effectively predict NH3 emissions from manure belt (MB) poultry layer facilities. This method can eliminate the need for tracking manure flow rates in traditional mass balance analyses for estimation of ammonia nitrogen (NH3-N) emissions. It was applied to three MB layer poultry houses in Ohio, with approximately 160,000 hens in each house, and validated using continuous NH3 emission measurement data. Feed, manure, and egg samples were collected from the three houses in different months over a year to evaluate possible seasonal variation in NH3 emissions from the poultry houses. The estimated NH3-N emissions from houses 1, 2, and 3 were 0.394 ±0.143, 0.293 ±0.1, and 0.284 ±0.129 g NH3-N hen-1 d-1, respectively, and the measured NH3-N emission rates were 0.200 ±0.067, 0.220 ±0.036, and 0.237 ±0.211 g NH3-N hen-1 d-1, respectively. These results are comparable with NH3-N emission rates published in the literature (0.024 to 0.592 g NH3-N hen-1 d-1). A statistical comparison of the measured and estimated NH3-N emissions showed that the root mean square error (RMSE), normalized mean square error (NMSE), and fractional bias (FB) were 0.179 g NH3-N hen-1 d-1, 0.426, and 0.457, respectively. These statistical parameters indicated that the estimations were acceptable according to the criteria of NMSE \u3c 0.5 and FB \u3c 0.5. The results showed that this alternative mass balance method could be used to estimate NH3-N emissions from MB poultry layer houses. However, the method estimates total nitrogen gas emissions, which is an upper limit of NH3-N emissions. A minimum of 22 sampling and modeling events is suggested for reliable estimation of NH3-N emission factors for MB poultry layer houses using the alternative mass balance method with a 90% confidence level (α = 0.1) and a maximum error of 15%

Quantitation and Dietary Risk Assessment of Hexazinone Residue in Blueberry Fruit

In order to determine the residue of hexazinone in blueberry fruit, field experiments in Zhejiang, Jilin, Liaoning and Beijing, China were conducted using 75% hexazinone water dispersible granules. An analytical method was established for determining residual hexazinone in blueberry fruit utilizing ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with an electrospray ionization source in the positive ion mode (ESI+). The samples were extracted with acetonitrile while vortexing, salted out, and then purified on a column packed with primary secondary amine (PSA) and C18 before measurement. The linearity, matrix effect, limit of quantification (LOQ), trueness (recovery rate) and precision (relative standard deviation (RSD)) of the proposed method were studied. Good linearity (r > 0.999 8) was found in the concentration range from 0.000 1 to 0.01 mg/L. The matrix effect was −7.7%. The LOQ was 0.01 mg/kg. The average recovery of hexazinone from blueberry fruit at spiked concentration levels of 0.01, 0.1 and 1.0 mg/kg ranged from 87% to 91%, with a RSD less than 3.7%. The field experiments showed that the residual level of hexazinone in blueberry fruit was below 0.01 mg/kg at 90 and 100 days after application, which was lower than the maximum residue limits (MRL) established in the US, Japan and South Korea (0.6, 0.2 and 0.05 mg/kg, respectively). The results of chronic dietary risk assessment showed that the estimated daily intake of hexazinone for general populations was 0.002 2 mg. The dietary risk quotient (RQ) was only 0.084%, indicating a low risk of dietary hexazinone intake. Therefore, it is recommended that 75% hexazinone water dispersible granules (WG) be applied in a single dose up to 1 800 g/hm2 to blueberry orchards; the pre-harvest interval (PHI) be 90 days