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Anaerobically digested swine wastewater has high concentrations of total ammoniacal nitrogen (TAN) (approximately 1,000 mg N L-1) and a low chemical oxygen demand (COD) to total nitrogen (TN) (COD/TN) ratio of <3.0, making it difficult to achieve a high TN removal rate using traditional biological nitrogen removal processes. The purpose of this study was to investigate the effectiveness of combining ammonia stripping (AS) and membrane bioreactor (MBR) processes to remove nitrogen from anaerobically digested swine wastewater. The coupling parameters that would lead to a high TN removal rate and cost effectiveness were also explored. Ammonia stripping was conducted at two pH levels of 10.0-10.5 (High-pH) and 9.0-9.5 (Low-pH). The MBR had the configuration of anoxic biofilm and aerobic MBR, and it was operated at two influent COD/TN ratios of 6.0-8.0 and 5.0-6.0 coupled with two TAN sludge loading rates in the oxic zone of 0.04-0.05 and 0.12-0.16 kg N kg-1 mixed liquid suspended solid (MLSS) d-1. Total nitrogen removal rate for the High-pH and Low-pH AS was 83% and 65%, respectively. In the MBR at a dissolved oxygen (DO) level of 6.12 -0.69 mg L-1, increasing the TAN sludge loading rate from 0.04 to 0.16 kg N kg-1 MLSS d-1 led to an increase in free ammonia from 0 to 4-9 mg L-1 and an increase in nitrite accumulation rate (NAR) from 0% to 71%. At a TAN sludge loading rate in the oxic zone of 0.12 kg N kg-1 MLSS d-1 and NAR of 53%, the TN removal rate reached 82% in the MBR through shortcut nitrification and denitrification (SND). The influent biochemical oxygen demand (BOD5) to TN (BOD5/TN) ratio was 1.41, COD/TN was 5.41, and the oxidation-reduction potential (ORP) of the denitrification zone was as low as -300 to -400 mV. Among the experimental conditions examined, the combined Low-pH AS+SND process provided the highest TN removal rate of 94% with the least cost and HRT. [ABSTRACT FROM AUTHOR]

Carbonaceous and nitrogenous gases are produced during storage of livestock manure, with the magnitude of production being affected by the chemical properties of the manure and the physical conditions of storage. This lab-scale study quantifies the emission rates of ammonia (NH3), nitric oxide (NO), and greenhouse gases (GHG), i.e., methane (CH4), carbon dioxide (CO2), nitrous oxide (N2O), from biogas digester effluent (BDE) stored at different depths of 1.0, 1.5, and 2.0 m in dynamic emission vessels (DEVs). The selected storage depths were reflective of the typical depth range of on-farm BDE storage in China. The static storage was held at a relatively constant media temperature of 15°C and an air exchange rate of 11.5 air changes per hour (ACH) for 78 days. Each depth regimen was replicated four times using four DEVs (12 DEVs total). The results showed that the mean (±SE) daily gaseous emission rates per volume of BDE stored at 1.0, 1.5, and 2.0 m depths, in g gas m-3 d-1, were, respectively, 9.1 (±0.7), 10.1 (±0.6), and 10.1 (±0.4) for CH4 (p = 0.39); 38.0 (±2.2), 34.5 (±1.3), and 30.7 (±0.6) for CO2 (p < 0.05); 1.9 (±0.11), 1.3 (±0.08), and 0.9 (±0.03) for NH3 (p < 0.05); and 6.7 (±0.5) x 10-3, 5.0 (±0.8) x 10-3, and 3.4 (±0.2) x 10-3 for N2O (p < 0.05). Nitric oxide (NO) emissions were negligible. The overall GHG (CH4 + N2O + CO2) emissions were dominated by CH4, which accounted for more than 85% of the CO2-equivalent emissions for all three storage depths. The CH4 emissions peaked during the early storage period, with the first 20-day cumulative emissions accounting for 56% to 58% of the total 78-day storage emissions. The results reveal that storage of BDE at 2.0 m depth yielded lower CO2, NH3, and N2O emission rates but similar CH4 emission rates compared to the 1.0 and 1.5 m depths. [ABSTRACT FROM AUTHOR]

Biogas digesters are commonly used in livestock farming in China. The digestion process converts large amounts of raw liquid manure (RLM) to biogas digester effluent (BDE). The BDE is then stored on the farm for some time before land application as crop or orchard nutrients. Storage of RLM or BDE is associated with gas emissions, although little information is available concerning comparison of air emissions between the two handling practices. This study was conducted to compare methane (CH4), carbon dioxide (CO2), nitrous oxide (N2O), and ammonia (NH3) emissions from RLM and BDE storages using dynamic emission vessels (DEVs). Both media were stored in closed vessels (50 L) at a 40 cm storage depth, a constant storage temperature of 30°C, and a headspace air exchange rate of 15 to 17 air changes per hour (ACH) for 22 days. The results showed that the average daily gas emission rates for RLM and BDE, in mg L-1 d-1, were, respectively, 102.9 and 125.3 CO2 (p < 0.05), 0.72 and 3.33 N2O (p < 0.05), 29.2 and 0.32 CH4 (p < 0.05), and 1.21 and 0.66 NH3 (p = 0.08). The total greenhouse gas (GHG = CH4 + CO2 + N2O) emissions were similar for RLM and BDE, 1.05 and 1.12 g CO2-eq L-1 d-1, respectively (p = 0.26). Nitrous oxide (N2O) emissions accounted for 88.2% of the CO2-eq GHG emissions for BDE, whereas CH4 emissions accounted for 69.7% of the CO2-eq GHG emissions for RLM. The high N2O emissions from BDE likely resulted from the lower COD/N ratio in BDE than RLM under the storage conditions. Differences in gaseous emission characteristics between RLM and BDE were attributed to the differences in methanogen species and the population of ammonia-oxidizing bacteria (AOB). [ABSTRACT FROM AUTHOR]

The effect of ventilation rate (VR) on ammonia and greenhouse gas emissions from co-composting dead hens mixed with hen manure was quantified. Three VR levels of 0.9, 0.7, and 0.5 m³ h-1 were evaluated. Gaseous concentrations were measured using a multi-gas infrared photoacoustic analyzer, VR was measured with flowmeters, and the gas emission rate was computed from the VR and gas concentration. Decomposition of the carcasses over the 11-week composting period was greater than 88%. VR was found to significantly affect NH3, CO2, and CH4 emissions (p < 0.05). Specifically, cumulative emissions per kg of initial matter for VR of 0.9, 0.7, and 0.5 m³ h-1 were, respectively, 2.4, 2.0, and 1.2 g NH3; 78, 66, and 42 g CO2; 120, 90, and 52 mg CH4; and 6.4, 6.1, and 5.1 mg N2O. Hence, the study results suggest that the ventilation rate can be adjusted to reduce NH3 and GHG emissions from animal mortality compositing. [ABSTRACT FROM AUTHOR]

This study quantifies concentrations and emission rates (ER) of ammonia (NH3) and greenhouse gases (GHG), including carbon dioxide (CO2) and methane (CH4), during four seasons of one year in north China from a naturally ventilated dairy cattle barn with a daily manure collection system, with each monitoring episode lasting five consecutive days. Gaseous concentrations of background and exhaust air were measured using an infrared photoacoustic multi-gas monitor with a multi-channel sampler. About 120 gas concentration measurements were taken for each season. Barn ventilation rate (VR) was determined by CO2 mass balance using literature metabolic rate data for dairy cattle. Both gas concentrations and ER showed considerable diurnal and seasonal variations. Annual mean (±SD) ER of NH3, CO2, and CH4 for the monitored dairy cattle barn were 75.5 ±253 g d-1 cow-1, 8.9 +0.7 kg d-1 cow-1, and 305 ±119 g d-1 cow-1, respectively. Ammonia and greenhouse gas ERfrom the current study were within the ranges of values reported for dairy cattle. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) emissions from laying hens are affected by nutrient content of the diet, manure quantity, and manure properties such as moisture content, nitrogen content, and pH. These production traits may vary with strain of the hen. However, limited information is available concerning the effects of laying-hen genetics on manure properties and NH3 emission. This study was conducted to comparatively quantify production performance, manure properties, and NH3 emissions (through N mass balance) of four white-egg-laying strains (Hy-Line W-36, Hy-Line W-98, Lohmann LSL Lite, and Bovans White) and four brown-egg-laying strains (Hy-Line Brown, Lohmann Brown, ISA Brown, and Bovans Brown) during two production periods of 27-28 weeks (PI) and 35-36 weeks (P2) of age. The diets were formulated to meet the nutritional needs of the brown and white hens. As a result, crude protein contents during PI and P2 were, respectively, 13.2% and 15.2% for the brown hens but 14.5% and 17.4% for the white hens. The results showed that the brown and white hens had similar hen-day egg production (97.5% to 89.2% for brown hens and 96.0% to 88.2% for white hens) and egg mass output (57.1 to 52.6 g d-1 hen-1 for brown hens and 55.6 to 51.2 g d-1 hen-1 for white hens) but different feed consumption (112 to 98 g d-1 hen-1 for brown hens and 101 to 93 g d-1 hen-1 for white hens, p < 0.01) and feed efficiency (1.97 to 1.87 g feed g-1 egg for brown hens and 1.82 g feed g-1 egg for white hens, p < 0.0001 and p = 0.11). The higher feed consumption for the brown hens stemmed from their heavier body mass (1.81 to 1.78 kg vs. 1.56 to 1.53 kg for white hens). Manure moisture content was higher for the brown hens than for the white hens, although the dry-matter manure production was not significantly different. The results further revealed that under the experimental conditions (i.e., higher CP contents of the diet for the white hens than for the brown hens) the white hens had higher NH3 emissions than the brown hens as expressed per hen (37% to 19% higher, p = <0.001 to 0.016), per animal unit (AU, 500 kg live body mass; 59% to 39% higher, p = 0.0007 to 0.007), per unit of egg mass output (41% to 24% higher, p = 0.01 to 0.09), per unit of feed N consumed (39% to 27% higher, p = 0.01 to <0.0001), and per unit of dry manure (56% to 39% higher, p = 0.001 to 0.007). Certain differences existed in production performance among strains within the brown or white hens, but no differences in NH3 emissions were detected. Because of the relatively small sample size (number of hens involved) and the relatively short monitoring period, the results should be referenced with these limitations in mind. Further larger-scale studies with longer monitoring periods to verify these findings are warranted. [ABSTRACT FROM AUTHOR]

This study quantifies concentrations and emission rates (ER) of ammonia (NH3) and greenhouse gases (GHG) including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from a naturally ventilated cage layer (Hy-Line brown strain) house with daily manure removal, located in northeast China during four seasons of one year, with each monitoring episode lasting five consecutive days. Gaseous concentrations of background and exhaust air were measured using an infrared photoacoustic multi-gas monitor with a multi-channel sampler. Building ventilation rate (VR) was determined by CO2 mass balance using literature metabolic rate data for modern laying hens. Both gas concentrations and ER showed considerable diurnal and seasonal variations. Annual mean (±SD) ER of NH3, CO2, CH4, and N2O for the monitored layer house were, in mg d-1 bird-1, 129 ±40.3, 78,250 ±15,384, 112 ±56.5, and 9.4 ±2.5, respectively, or in g d-1 AU-1 (AU = 500 kg live body weight), 33.4 ±11.4, 19,975 ±3,071, 29.2 ±15.2, and 2.5 ±0.7, respectively. Ammonia ER from the current study was within the ranges of values reported for high-rise houses with annual manure removal and manure-belt houses with daily manure removal. Results of the study contribute to improving ammonia and GHG emissions inventory for animal feeding operations in China and worldwide. [ABSTRACT FROM AUTHOR]

Gas analyzers are commonly protected from impurities in air sampling via use of in-line dust filters to ensure operational performance and longevity of the instruments. This is especially true with extended periods of air quality monitoring in dusty environments. Prices for commercially available filters and monitoring needs vary considerably. A question that has often come up but has not received much investigation is how the filter media types (e.g., paper vs. Teflon) and operational conditions (clean vs. dirty) impact the integrity of gaseous concentration measurement. The study reported here was conducted toward addressing this issue. Specifically, the study assessed the magnitude of ammonia (NH3) adsorption for several types of in-line filters and conditions often used or encountered in animal feeding operation air emission studies, namely, Teflon (most expensive), paper (least expensive), and stand-alone automobile fuel filters, being either clean (new) or dust-laden. Three nominal NH3 levels (20, 45, or 90 ppm, generated with poultry manure) coupled with two nominal airflow rates (4 vs. 8 L/min or 8 vs. 16 L/min) through the filters were used in the evaluation. The types of dust used in the study included corn starch and broiler-house dust. Simultaneous measurements of NH3 concentrations before and after the tested filter were made with two photoacoustic gas spectrometers. The results revealed that NH3 adsorption was highest for the fuel filter initially but negligible for the Teflon filters. However, after 30 min exposure, relative NH3 adsorption by the filters mostly fell below 1%. The higher flow rate led to significantly lower relative NH3 adsorption for both the fuel and paper filters (P < 0.001) but made no difference for the Teflon filters (P = 0.31 to 0.49). During fresh-air purging of the fuel filters laden with broiler-house dust, NH3 was initially released but diminished after 15 min. The results suggest that when used properly (e.g., proper flow rate), the in-line dust filters tested in this study (fuel, paper, and Teflon) offer viable, performance-based options for air emissions (especially NH3) measurement applications. [ABSTRACT FROM AUTHOR]

Hoop structures have been used quite widely for animal production in the U.S. due to their lower capital costs and multi-purpose versatility. Hoop barns for grower-finisher (G-F) swine production have attracted attention in China as an alternative, environmentally friendly, and water-saving production system. This study was conducted to assess concentrations and emissions of ammonia (NH3) and greenhouse gases (GHGs) for a hoop G-F pig barn at a commercial pig operation in suburban Beijing, China. The NH3 and GHG concentrations and emissions of the facility were measured for three consecutive days during spring and summer seasons. The results revealed the following hourly gaseous concentrations (mean ± SD, mg m-3): 5.9 ± 2.7 NH3, 2,183 ± 1,376 CO2, and 4.0 ± 2.5 CH4 in spring, and 6.8 ± 3.4 NH3, 1,530 ± 364 CO2, and 5.0 ± 2.3 CH4 in summer. The estimated gaseous emissions averaged, in g pig-1 d-1, 22.7 NH3, 2,003 CO2, and 6.7 CH4, or in g AU-1 d-1 (AU = 500 kg), 124 NH3, 11,264 CO2, and 36.2 CH4. The emission values from this study, while being generally comparable with those reported in the literature, add new information concerning emissions from alternative swine housing system. [ABSTRACT FROM AUTHOR]