Search Results (223)

This study aims to characterize the emissions of ammonia (NH₃) and methane (CH₄) from naturally ventilated dairy barns located in cold regions during the winter season, thereby providing a scientific basis for optimizing dairy barn environmental management. The target barn was selected at a commercial dairy farm in Ulanchab, Inner Mongolia, China. Environmental factors, including temperature, humidity, wind speed, and concentrations of NH₃, CH₄, and CO₂, were monitored both inside and outside the barn. The ventilation rate and emission rate were calculated using the CO₂ mass balance method. Additionally, NH₃ and CH₄ emission prediction models were developed using the adaptive neural fuzzy inference system (ANFIS). Correlation analyses were conducted to clarify the intrinsic links between environmental factors and NH₃ and CH₄ emissions, as well as the degree of influence of each factor on gas emissions. The ANFIS model with a Gaussian membership function (gaussmf) achieved the highest performance in predicting NH₃ emissions (R² = 0.9270), while the model with a trapezoidal membership function (trapmf) was most accurate for CH₄ emissions (R² = 0.8977). The improved ANFIS model outperformed common models, such as multilayer perceptron (MLP) and radial basis function (RBF). This study revealed the significant effects of environmental factors on NH₃ and CH₄ emissions from dairy barns in cold regions and provided reliable data support and intelligent prediction methods for realizing the precise control of gas emissions. Full article

This study evaluated the impact of a ground channel ventilation system on seasonal ammonia emissions in a swine-finishing barn over three distinct seasons: summer, late autumn, and winter. The ground channel system tempered inlet air, cooling it during summer and warming it during colder seasons, maintaining stable room temperatures despite external fluctuations. During summer, the ground channel reduced the incoming air temperature from 26.9 °C to 22.5 °C, contributing to steady barn temperatures (28.0 °C) and mitigating ammonia emissions, which reached 111.0 ± 23.6 g day⁻¹ AU⁻¹. In late autumn and winter, it warmed the inlet air from 4.7 °C and −0.7 °C to 8.1 °C and 6.8 °C, respectively, maintaining stable room temperatures (25.1 °C and 24.3 °C). Ammonia emissions remained consistent across seasons, with 125.0 ± 37.3 g day⁻¹ AU⁻¹ in late autumn and 107.1 ± 20.5 g day⁻¹ AU⁻¹ in winter. Thus, ammonia emissions showed no seasonal differences, highlighting the system’s effectiveness in balancing ventilation rates with emissions. During late autumn and winter, it improved air quality without compromising thermal comfort for the swine. In summer, the reduced ventilation demand lowered ammonia emissions, supporting the effective management of ammonia emissions year-round. Future research should investigate the system’s effects on other gases and slurry pit temperatures. Full article

The addition of alkaline amendments is considered an important strategy to alleviate soil acidification, with profound impacts on soil nitrogen (N) transformations such as nitrification as well as greenhouse gas (GHG) nitrous oxide (N₂O) emissions. Nitrification inhibitors (NIs) have been widely recognized to effectively mitigate N₂O emissions by depressing the nitrification process. However, the effectiveness of NIs on N₂O emissions reduction under different alkaline amendments remains largely unknown, hindering our knowledge of the optimal soil acidification mitigation strategies. In this study, the effects of NIs in combination with different alkaline amendments on N₂O emissions were assessed on typical acid soils collected from four sites during a 28-day aerobic incubation experiment. Treatments included four alkaline amendments (quicklime, chicken manure, cow dung, biochar) and no amendment control, designated as CaO, CM, CD, BC, and CK, combined with a typical NI (3,4 dimethylpyrazole phosphate, DMPP) applied at 2 mg soil kg⁻¹ or non-NI applied, respectively. Both individual amendments and their combination with DMPP significantly elevated the soil pH by 4.9–64.2% compared with the CK treatment, with the effectiveness ranking as CaO > CM ≈ CD > BC. Cumulative N₂O emissions were stimulated by the individual application of CaO, CM, and CD but were reduced by BC application compared with the CK treatment. Changes in N₂O emissions were positively correlated with the responses of the net N mineralization and nitrification rates to individual amendments, which were regulated by changes in the soil pH. The suppressive effects of NI combined with individual amendments on N₂O emissions were significant in the CaO treatment with a reduction ranging from 3.3% to 60.2%, which was attributed to decreased abundances of ammonia-oxidizing bacteria (AOB). Therefore, we concluded that the combined application of CaO and DMPP could be considered as a suitable mitigation strategy for addressing soil acidification through optimized N management. Additionally, BC can serve as a supplementary practice to simultaneously improve soil fertility. These insights are crucial for developing integrated fertilization management strategies to mitigate soil acidification with low N loss risks. Full article

The ammonia energy ratio (AER) is a critical parameter influencing the performance of ammonia/diesel dual-fuel engines. In this study, a numerical simulation was conducted based on a high-pressure dual-fuel (HPDF) direct injection ammonia/diesel engine to investigate the impact of the AER on combustion and emissions under two distinct combustion modes. By adjusting the ammonia start of injection timing (ASOI), the combustion mode was transitioned from diffusion combustion (HPDF1) to partially premixed combustion (HPDF2). The results show that under the HPDF1 mode, a three-stage heat release pattern is observed, and the evolution curves of NO and NO₂ exhibit fluctuations similar to the heat release process. As the AER increases, the second heat release stage is suppressed, the high-temperature region narrows, the ignition delay is extended, and the CA10–CA50 interval shortens, leading to a higher maximum pressure rise rate (MPRR) at a high AER. Conversely, in the HPDF2 mode, the combustion process is characterized by a two-stage heat release. With an increasing AER, the high-temperature region expands, the ignition delay and CA10–CA50 interval are prolonged, while the CA50–CA90 interval shortens, and the MPRR becomes the lowest at a high AER. For both combustion modes, total greenhouse gas (GHG) emissions decrease with an increasing AER. However, in the HPDF2 mode with an AER = 95%, N₂O accounts for up to 78% of the total GHG emissions. Additionally, a trade-off relationship exists between NOx emissions and indicated thermal efficiency (ITE). When the ASOI is set to −8°CA ATDC, the engine operates in a transitional combustion mode between HPDF1 and HPDF2. At this point, setting the AER to 95% effectively mitigates the trade-off, achieving an ITE of 53.56% with NOx emissions as low as 578 ppm. Full article

The selective catalytic reduction (SCR) of NO_x emissions by hydrocarbons (HCs) using a silver (Ag)-based catalyst offers significant advantages over conventional SCR systems that rely on ammonia reductants and vanadium-based catalysts. However, the conversion rate of SCR is influenced by several factors, among which catalyst poisoning is a major concern. Toxic metals such as sodium (Na), potassium (K), magnesium (Mg), and calcium (Ca) can degrade catalyst activity and lead to deactivation. Poisoned catalysts suffer from reduced conversion rates and premature deactivation before reaching their intended operational lifespan. In particular, calcium poisoning results in the formation of CaO (calcium oxide), which reacts to produce a CaWO₄ compound that severely impairs SCR performance. This study investigates the role of antimony (Sb) in mitigating Ca-induced deactivation in HC-SCR of NO_x. Five catalysts with varying Sb loadings were prepared and tested to evaluate Sb’s effect on NO_x conversion rate at a space velocity of 30,000 h⁻¹. The results demonstrate that Sb effectively suppresses Ca deactivation, enhancing the conversion rate across all engine test conditions. The highest NO_x conversion rate (95.88%) was achieved using a catalyst with 3% Sb. Full article

This review assesses biochar’s potential to mitigate nitrogen (N) losses when co-applied with N fertilizers, emphasizing mechanisms linked to its measurable physicochemical properties. The mitigation of ammonia (NH₃) volatilization shows variable effects from its cation exchange capacity (−21.7% to 20.4%) and specific surface area (SSA; −23.8% to 39.1%). However, the biochar pH (influencing mitigation from −45.0% to −9.0%) and application rate are key factors, with clayey soils exhibiting the greatest mitigation (−52.2%), potentially due to their high bulk density. High SSA biochar, often from high pyrolysis temperatures, reduces nitrate-N (NO₃⁻-N) leaching (up to −26.6%) by improving the soil’s water-holding capacity. A co-application with organic fertilizers shows a pronounced mitigation (up to −39.0%) due to a slower N release coupled with biochar adsorption. A high SSA also plays an important role in mitigating nitrous oxide (N₂O) emissions (up to −25.9%). A higher biochar C/N ratio promotes microbial N immobilization, contributing to N₂O reductions (+1.5% to −34.2%). Mitigation is greater in sandy/loamy soils (−18.7% to −7.9%) than in clayey soils, where emissions might increase (+18.0%). Overall, biochar applications demonstrate significant potential to mitigate N losses and improve N use efficiency, thereby supporting sustainable agriculture; however, its effectiveness is optimized when biochar properties (e.g., high SSA and appropriate C/N ratio) and application strategies are tailored to specific soil types and N sources. Full article

PM₁₀ samples were collected at an urban site of Zhuozhou, the southern gateway of Beijing, from 28 December 2021 to 29 January 2022, in order to explore the chemical composition, sources and physical and chemical formation processes of prominent components. The results showed that five trace elements (Mn, Cu, As, Zn and Pb) had high enrichment in PM₁₀ and were closely related with anthropogenic combustion and vehicle emissions; organic and element carbon had a high correlation due to the same primary sources and similar evolution; nitrate dominated SNA (sulfate, nitrate, ammonium) and nitrate/sulfate ratios reached 2.35 on the polluted days owing to the significant contribution of motor vehicle emissions. Positive matrix factorization analysis indicated that secondary source, traffic, biomass burning, industry, coal combustion and crustal dust were the main sources of PM₁₀, contributing 32.5%, 20.9%, 15.0%, 13.9%, 9.4% and 8.3%, respectively; backward trajectories and potential source contribution function analysis showed that short-distance airflow was the dominant cluster and accounted for nearly 50% of total trajectories. The Weather Research and Forecasting model with Chemistry, with integrated process rate analysis, showed that dominant gas-phase reactions (heterogeneous reaction) during daytime (nighttime) in presence of ammonia led to a significant enhancement of nitrate in Zhuozhou, contributing 12.6 μg/m³ in episode 1 and 22.9 μg/m³ in episode 2. Full article

The application of digestate as a fertilizer offers a promising alternative to synthetic inputs on permanent grasslands, with benefits for productivity and environmental performance. This four-year study evaluated the impact of two digestate application methods—disc injection (I) and band spreading (S)—combined with four dose variants (0, 20, 40, and 80 m³·ha⁻¹), including split-dose strategies. Emissions of ammonia (NH₃), carbon dioxide (CO₂), and methane (CH₄) were measured using wind tunnel systems immediately after application. Vegetation status was assessed via Sentinel-2-derived Normalized Difference Vegetation Index, Normalized Difference Water Index, and Modified Soil Adjusted Vegetation Index, and agronomic performance through dry matter yield (DMY), net energy for lactation (NEL), and relative feed value (RFV). NH₃ and CO₂ emissions increased proportionally with digestate dose, while CH₄ responses suggested a threshold effect, but considering solely the disc injection, CH₄ flux did not increase markedly with higher application rates. Disc injection resulted in significantly lower emissions of the monitored fluxes than band spreading. The split-dose I_40+40 variant achieved the highest DMY (3.57 t·ha⁻¹) and improved forage quality, as indicated by higher NEL values. The control variant (C, no fertilization) had the lowest yield and NEL. These results confirm that subsurface digestate incorporation in split doses can reduce emissions while supporting yield and forage quality. Based on the findings, disc injection at 40+40 m³·ha⁻¹ is recommended as an effective option for reducing emissions and maintaining productivity in managed grasslands. Full article

Objective: Current good manufacturing practice (cGMP) guidance for positron emission tomography (PET) drugs has been established in Europe and the United States. In Japan, the Pharmaceuticals and Medical Devices Agency (PMDA) approved the use of radiosynthesizers as medical devices for the in-house manufacturing of PET drugs in hospitals and clinics, regardless of the cGMP environment. Without adequate facilities, equipment, and personnel required by cGMP regulations, the quality assurance (QA) and clinical effectiveness of PET drugs largely depend on the radiosynthesizers themselves. To bridge the gap between radiochemistry standardization and site qualification, the Japanese Society of Nuclear Medicine (JSNM) has issued guidance for the in-house manufacturing of small-scale PET drugs under academic GMP (a-GMP) environments. The goals of cGMP and a-GMP are different: cGMP focuses on process optimization, certification, and commercialization, while a-GMP facilitates the small-scale, in-house production of PET drugs for clinical trials and patient-specific standard of care. Among PET isotopes, N-13 has a short half-life (10 min) and must be synthesized on site. [¹³N]Ammonia ([¹³N]NH₃) is used for myocardial perfusion imaging under the Japan Health Insurance System (JHIS) and was thus selected as a working example for the manufacturing of PET drugs in an a-GMP environment. Methods: A [¹³N]NH₃-radiosynthesizer was installed in a hot cell within an a-GMP-compliant radiopharmacy unit. To comply with a-GMP regulations, the air flow was adjusted through HEPA filters. All cabinets and cells were disinfected to ensure sterility once a month. Standard operating procedures (SOPs) were applied, including analytical methods. Batch records, QA data, and radiation exposure to staff in the synthesis of [¹³N]NH₃ were measured and documented. Results: 2.52 GBq of [¹³N]NH₃ end-of-synthesis (EOS) was obtained in an average of 13.5 min in 15 production runs. The radiochemical purity was more than 99%. Exposure doses were 11 µSv for one production run and 22 µSv for two production runs. The pre-irradiation background dose rate was 0.12 µSv/h. After irradiation, the exposed dosage in the front of the hot cell was 0.15 µSv/h. The leakage dosage measured at the bench was 0.16 µSv/h. The exposure and leakage dosages in the manufacturing of [¹³N]NH₃ were similar to the background level as measured by radiation monitoring systems in an a-GMP environments. All QAs, environmental data, bacteria assays, and particulates met a-GMP compliance standards. Conclusions: In-house a-GMP environments require dedicated radiosynthesizers, documentation for batch records, validation schedules, radiation protection monitoring, air and particulate systems, and accountable personnel. In this study, the in-house manufacturing of [¹³N]NH₃ under a-GMP conditions was successfully demonstrated. These findings support the international harmonization of small-scale PET drug manufacturing in hospitals and clinics for future multi-center clinical trials and the development of a standard of care. Full article

This study investigated the effects of dietary carbohydrate levels (control 8.13%, HG1 12.03%, and HG2 14.15%) on growth performance and glutamate metabolism in Chinese perch (S. chuatsi) (initial weight: 39.12 ± 0.25 g) reared at 12–15 °C. Diets were isonitrogenous (49% protein). After 8 weeks, the HG1 group optimized weight gain rate (WGR), specific growth rate (SGR), and protein efficiency ratio (PER), while reducing feed conversion ratio (FCR). HG1 and HG2 groups reduced liver glutamate/glutamine levels while downregulating the expression of key ammonia-metabolizing genes (gs, gdh, and ampd), collectively suppressing glutamate-mediated ammonia excretion. HG1 and HG2 groups enhanced glycolysis (upregulated gk and pk) coupled with suppressed gluconeogenesis (decreased PEPCK and G6Pase activities) in the liver. Concurrent downregulation of proteolytic markers (mafbx and murf1) in the muscle indicated improved protein conservation efficiency in the HG1 and HG2 groups. The HG1 diet optimally enhances growth by promoting glycolysis, reducing ammonia excretion, and improving feed efficiency. The insights gained from this research will be used to refine the low-temperature culture feed for Chinese perch, aiming to decrease ammonia and nitrogen emissions, thereby advancing the practice of low-ammonia emission culture for this species. Full article

Ammonia (NH₃) is a significant air pollutant with major environmental and health impacts, largely attributed to agriculture. Pig production is a major contributor, accounting for 25% of livestock NH₃ emissions. This study developed a new system based on gas-permeable membranes (GPM) technology for NH₃ recovery from the atmosphere obtaining a solution of ammonium sulfate as the resulting fertilizer product. Various experimental configurations were evaluated in the novel system using a synthetic NH₃-emitting solution. The optimal arrangement was a GPM system with recirculation of the generated NH₃ and without recirculation of the acidic trapping solution, yielding a nitrogen (N) recovery rate of up to 237 g m⁻² d⁻¹. Subsequent tests using pig manure (PM) at varying durations achieved rates of up to 73 g m⁻² d⁻¹, representing a four-fold increase in N capture efficiency compared to previous research. The influence of manure temperature on NH₃ emission and capture were analyzed, simulating the possible differences between seasons (summer and winter), and revealing higher N recovery rates at elevated temperatures. At 21.5 °C, the recovery rate was 7.7 g m⁻² d⁻¹, while increased temperatures of 38.8 °C and 49.3 °C yielded rates of 15.9 and 27.2 g m⁻² d⁻¹, respectively. Full article

Ammonia (NH₃) plays a vital role in both the agriculture and energy sectors, serving as a precursor for nitrogen fertilizers and as a promising carbon-free fuel and hydrogen carrier. However, the conventional Haber–Bosch process is highly energy-intensive, operating under elevated temperatures and pressures, and contributes significantly to global CO₂ emissions. In recent years, nonthermal plasma (NTP)-assisted ammonia synthesis has emerged as a promising alternative that enables ammonia production under mild conditions. With its ability to activate inert N₂ molecules through energetic electrons and reactive species, NTP offers a sustainable route with potential integration into renewable energy systems. This review systematically summarizes recent advances in NTP-assisted ammonia synthesis, covering reactor design, catalyst development, plasma–catalyst synergistic mechanisms, and representative reaction pathways. Particular attention is given to the influence of key plasma parameters, such as discharge power, pulse voltage, frequency, gas flow rate, and N₂/H₂ ratio, on reaction performance and energy efficiency. Additionally, comparative studies on plasma reactor configurations and materials are presented. The integration of NTP systems with green hydrogen sources and strategies to mitigate ammonia decomposition are also discussed. This review provides comprehensive insights and guidance for advancing efficient, low-carbon, and distributed ammonia production technologies. Full article

The combustion of ammonia with oxygen presents a promising pathway for global energy transformation using carbon dioxide-neutral energy solutions and carbon capture. Ammonia, a carbon-free fuel, offers several benefits, owing to its non-explosive nature, high octane rating, and ease of storage and distribution. However, challenges such as low flammability and excessive nitrogen oxide (NO_x) emissions must be addressed. This paper explores the recent advances in ammonia oxy-combustion and highlights recent experimental and numerical research on NO_x emission traits, combustion, and flame propagation across various applications, including gas furnaces, internal combustion engines, and boilers. Furthermore, this review discusses the diverse approaches to overcoming the challenges of ammonia combustion, including oxygen enrichment, fuel blending, plasma assistance, preheating, multiple injections, and burner design modifications. By summarizing the advancements in ammonia oxy-combustion investigation, this paper aims to provide valuable insights that can serve as reference information for prospective ammonia oxy-combustion research and applications toward the transition to sustainable energy. Full article

In recent years, there has been an increase in the emission of tire wear particle (TWP) microplastics from wastewater treatment plants into the environment. The aim of this study was to determine the effect of TWPs in wastewater flowing into a biological reactor on the transcription of the 16S rRNA gene and the key genes responsible for nitrogen metabolism, amoA, nirK and nosZ, in aerobic granular sludge. The laboratory experiment was carried out in sequencing aerobic granular sludge reactors operated in an 8 h cycle into which TWP microplastics were introduced with municipal wastewater at a dose of 50–500 mg TWPs/L. The ammonia removal rate and the production of oxidized forms of nitrogen increased with the TWP dose. Gene transcript abundance analysis showed that the presence of rubber and substances leached from it promoted the activity of ammonium-oxidizing bacteria (160% increase), while the transcription of genes related to denitrification conversions was negatively affected. The activity of nitrite reductase gradually decreased with increasing TWP concentration in wastewater (decreased by 33% at 500 mg TWPs/L), while nitric oxide reductase activity was significantly inhibited even at the lowest TWP dose (decreased by 58% at 500 mg TWPs/L). The data obtained indicate that further studies are needed on the mechanisms of the effects of TWPs on the activities of the most important groups of microorganisms in wastewater treatment to minimize the negative effects of TWPs on biological wastewater treatment. Full article

Solar power generation systems, recognized for their high energy quality and environmental benefits, require efficient energy storage to ensure stable grid integration and reduce reliance on fossil fuels. Thermochemical energy storage (TCS) using metal oxides, such as the Mn₂O₃/Mn₃O₄ redox system, offers advantages like high energy density, wide temperature range, and stability, making it ideal for solar power applications. This study investigates Mn₃O₄ and Mn₂O₃ as initial reactants, analyzing reaction temperature range, rate, conversion efficiency, and cyclic performance via synchronous thermal analysis. Microstructural characterization was performed using XRD, SEM, BET, XPS, nanoparticle size, and zeta potential measurements. The results show that Mn₃O₄ reversibly converts to Mn₂O₃ with over 100% conversion efficiency over five cycles with 3.3% weight loss, indicating stable performance. Mn₃O₄ oxidation follows Arrhenius’ Law below 700 °C but deviates at higher temperatures. The oxidation mechanism function is G(α) = α and f(α) = 1, with an activation energy of 20.47 kJ/mol and a pre-exponential factor of 0.268/s. Mn₂O₃ synthesized via ammonia precipitation exhibits reversible redox behavior with 3.3% weight loss but samples from low-concentration precursors show poor cyclic performance. The reduction reaction of Mn₂O₃ has an activation energy of 249.87 kJ/mol. By investigating the Mn₂O₃/Mn₃O₄ redox system for TCS, this study advances its practical integration into solar thermal power systems and offers critical guidance for developing scalable, low-carbon energy storage technologies. These findings can support Sustainable Development Goals (SDGs) by advancing renewable energy storage technologies, reducing carbon emissions, and promoting the integration of solar power into sustainable energy grids. Full article