Search Results (175)

Reducing the environmental impact of animal production is a major challenge in the context of climate change and sustainable agriculture. Although rabbit farming is generally considered less resource-intensive than other livestock systems, it still contributes to emissions of ammonia (NH₃), hydrogen sulfide (H₂S), and methane (CH₄), which can negatively affect air quality and the climate. This study aimed to evaluate whether dietary supplementation with selected natural feed additives could mitigate gaseous emissions and lower the environmental footprint of rabbit production. An experimental feeding trial was conducted in which gaseous emissions from rabbit housing were monitored, and the gas composition of feces was analyzed. Emissions were quantified and expressed as carbon dioxide equivalents (CO₂e) to allow comparative assessment of environmental impact. The inclusion of natural feed additives significantly reduced the emission of gaseous pollutants compared with the control diet, resulting in a lower calculated environmental footprint of the production system. These findings indicate that targeted modification of rabbit diets using natural feed ingredients can be an effective strategy for reducing harmful gaseous emissions and enhancing the environmental sustainability of rabbit farming. Full article

Membrane distillation (MD) was a promising approach for treating highly concentrated ammonia–nitrogen wastewater. However, membrane wetting often limited large-scale application. To address this, we built an anti-wetting layer on a commercial PVDF membrane surface by coating fluoride and depositing SiO₂ nanoparticles. Three PVDF/ SiO₂/F membranes were prepared with different silicon contents: 1%, 6%, and 12% (volume) of tetraethyl orthosilicate (TEOS). These processes created different surface roughness on the modified membranes. Results showed that the membrane containing 6% TEOS exhibited the best resistance to sodium dodecyl sulfate (SDS) in NaCl solution. This optimized membrane was subsequently tested with real wastewater, including source-separated urine and landfill leachate. In 10 h, it removed 97.5% of total organic carbon (TOC) from urine, achieving an ammonia absorption rate of 55.1% and removed 92.4% from leachate, with an ammonia absorption rate of 37.58%. These results provide a reference for membrane fabrication parameter optimization to enhance the membrane’s anti-wetting ability. Full article

Ammonia nitrogen stands as a pivotal water quality indicator within the frameworks of aquatic ecological quality assessment and aquatic ecological governance systems. This study focuses on the adsorption method, selecting four inorganic adsorbents—clinoptilolite, volcanic rock, bentonite, and fly ash—as research subjects, and introduces rare earth modifiers for rare earth-loading modification. Various modifications were applied to the adsorbents to enhance their ammonia nitrogen adsorption efficacy. Combined with material characterization, the microscopic features and adsorption behaviors of the adsorbents were elucidated, aiming to provide a theoretical foundation for addressing practical engineering challenges and to screen out the optimal inorganic adsorbent and the most effective modification protocol. Based on the experimental findings, cerium chloride modification can significantly enhance the ammonia nitrogen adsorption performance of clinoptilolite. Under the optimal preparation conditions (cerium chloride concentration: 1.0%, solid–liquid ratio: 1:40, pH = 9), the ammonia nitrogen removal efficiency reaches 85.45%. This modification process leads to the formation of new substances: a large amount of cerium oxide and cerium hydroxide are loaded onto the surface of clinoptilolite, which contributes to the increases in specific surface area (21.92 m²/g), average pore diameter (12.27 nm), and total pore volume (0.07 cm³/g). Furthermore, during the modification, cerium hydroxide undergoes hydroxylation, rendering the clinoptilolite surface negatively charged—this facilitates the adsorption of ammonia nitrogen via electrostatic interaction. Notably, the characteristic structural peaks of clinoptilolite remain unchanged before and after modification, indicating that the modification primarily acts on the material surface. This not only improves the ammonia nitrogen adsorption efficiency but also preserves the structural stability of clinoptilolite. Full article

Hemp hurds (HHs), a lignocellulosic agricultural waste, have the potential for bioconversion into bio-based products. However, the matrix structure of biomass comprising cellulose, hemicellulose, and lignin makes cellulose inaccessible. Pre-treatment is essential for accessing cellulose by removing lignin, hemicellulose, and extractives. This study compares lignocellulose structure modification of HH using low-concentration chemical pretreatment methods, including organosolvent, 60% ethanol (EtOH), 3% hydrogen peroxide with 3% ammonia (H₂O₂/NH₃), and 2% sodium hydroxide (NaOH) with sonication. X-ray diffractor (XRD) analysis, using Segal method as a guide, showed that post treatments, the crystallinity index increased from 39.26% in untreated HH to 65.80% for NaOH-treated hurds. Polysaccharide content decreased compared to HH, attributed to the combination of solubilisation of hemicellulose, degradation of amorphous carbohydrates, and loss of sample during treatment wash. Although there was a reduction in polysaccharide content compared to HH, NaOH treated HH showed the highest total carbohydrate content of 48.6% and the most disrupted surface structure, based on scanning electron microscope (SEM) images at 2000× magnification. Fourier-transform infrared spectrophotometer (FTIR) analysis indicated a reduction in lignin and hemicellulose peaks for NaOH and H₂O₂/NH₃ treatments, while thermogravimetric analyser (TGA) and derivative thermogravimetric analysis (DTG) results showed improved thermal stability for NaOH-treated samples. The ultrasound-assisted NaOH-treated sample had the most structural disruption in recovered solid fraction, based on comparative compositional and structural analyses. This gives a guide on the selection of pretreatment to pursue for HH processing. Full article

Hydrogen-fueled gas turbines face challenges related to flashback risk, nitrogen oxide (NO_x) emissions, and operational flexibility. In this study, a Center-Graded Spiral Micromixing (CGSM) combustor was designed and experimentally investigated to enhance the robustness of fuel–air mixing under hydrogen-rich conditions. The proposed CGSM concept employs spiral microtubes to induce curvature-driven secondary flows, promoting mixing through airflow-controlled mechanisms rather than relying solely on fuel jet momentum. Numerical simulations were conducted to qualitatively analyze the internal flow and mixing characteristics of the spiral microtubes, followed by pressurized combustor experiments at an inlet pressure of 0.3 MPa and elevated air temperatures. The experimental results demonstrate stable combustion of pure hydrogen under lean conditions, with NO_x emissions being maintained below 25 ppm, corrected to 15% O₂, without observable flashback or combustion oscillations within the designated operating range (from ignition to full load). The combustor further exhibits stable operation with blended hydrogen–methane and hydrogen–ammonia fuels, enabling online fuel switching without hardware modification. Application tests on an 80 kW micro-gas turbine indicate that the CGSM combustor can support stable operation across the full range of load conditions, from ignition to full-load operation, under both simple- and reheat-cycle modes, with performance characteristics that are consistent with established operational standards for micro-gas turbines. These results suggest that the CGSM concept provides a feasible micromixing strategy for hydrogen and hydrogen-rich fuels at a moderate pressure and micro-gas turbine scale. Full article

This study investigated the characterization and application of organoclay formulations in a chemoautotrophic biofloc system. Organoclays were produced using the calcination method and bentonite, chitosan, corn, and tapioca starches as ingredients. Thermogravimetric analysis confirmed the high thermal stability of bentonite, whereas biopolymers (tapioca, chitosan, and corn starch) exhibited greater thermal sensitivity and a lower residual mass. Scanning electron microscopy revealed that organoclays had increased porosity (4–21 µm) compared to bentonite, while energy-dispersive spectroscopy confirmed the retention of key chemical elements. X-ray diffraction and Fourier-transform infrared spectroscopy indicated structural modifications due to thermal processing. In aqueous conditions, bentonite and organoclays disaggregated into particles with sizes between 0.76 and 1.24 μm. Based on these physicochemical properties, three formulations were selected for nitrification trials due to their stability in water, O1 (bentonite + tapioca), O2 (bentonite + tapioca + chitosan), and O6 (bentonite + corn starch), along with a 100% bentonite treatment and a control group (C) supplemented with inorganic salts and artificial Needlona^® substrates. All treatments achieved full nitrification within 37 days, with O1 exhibiting the best performance by maintaining ammonia and nitrite levels within safe thresholds. These findings suggest that organoclays, particularly O1, can enhance nitrification stability, providing a promising strategy for water quality management in intensive aquaculture systems. Full article

The pursuit of sustainable ammonia production has accelerated the development of electrocatalytic pathways capable of operating under ambient conditions with renewable electricity. Recent studies have revealed that the efficiency and selectivity of both electrochemical nitrogen reduction reaction (eNRR) and nitrate reduction reaction (eNO₃RR) are not governed solely by catalyst composition, but by the synergistic interplay among electrolyte identity, interfacial solvation structure, and catalyst architecture. Hydrated cations such as Li⁺ profoundly reshape the electric double layer, polarize interfacial water, and lower activation barriers for key proton–electron transfer steps, thereby redefining the electrolyte as an active promoter. Parallel advances in structural engineering, including alloying, heteroatom doping, controlled defect formation, and nanoscale morphological control, have enabled the optimization of intermediate adsorption energies while simultaneously suppressing competing hydrogen evolution. In addition, the emergence of metal–organic-framework (MOF)-derived single-atom catalysts has demonstrated that atomically dispersed transition-metal centers anchored within dynamically adaptable matrices can deliver exceptional Faradaic efficiencies, high turnover rates, and long-term operational durability. These developments highlight a unified strategy in which electrolyte–catalyst coupling, rational structural modification, and atomic-scale design principles converge to enable predictable and high-performance ammonia electrosynthesis. This review integrates mechanistic insights across these domains and outlines future directions for translating molecular-level understanding into scalable technologies for green ammonia production. Full article

Phenylalanine ammonia-lyase (PAL) is the core branch-point enzyme connecting plant primary aromatic amino acid metabolism to the phenylpropanoid pathway, which determines carbon flux redistribution between growth and defense and is essential for plant adaptation to various environments. Extensive research has clarified PAL’s conserved homotetrameric structure, MIO cofactor-dependent catalytic mechanism, and its roles in plant growth, development, and stress responses. However, there is a lack of comprehensive review studies focusing on PAL-mediated carbon metabolic flux redistribution, specifically covering its structural and evolutionary foundations, the links between this flux regulation and plant growth/development, its multi-layered regulatory network, and its roles in stress adaptation, limiting a comprehensive understanding of its evolutionary and functional diversity. This review systematically covers four core aspects: first, the molecular foundation, encompassing PAL’s structural features and catalytic specificity governed by the MIO cofactor; second, evolutionary diversity spanning from algae to angiosperms, with emphasis on unique regulatory mechanisms and evolutionary significance across lineages; third, the multi-layered regulatory network, integrating transcriptional control, post-translational modifications, epigenetic regulation, and functional crosstalk with phytohormones; and fourth, functional dynamics, which elaborate PAL’s roles in organ development, including root lignification, stem mechanical strength, leaf photoprotection, flower and fruit quality formation, and lifecycle-wide dynamic expression, as well as its mediated stress adaptations and regulatory networks under combined stresses. These insights provide a theoretical basis for targeted manipulation of PAL to optimize crop carbon allocation, thus improving growth performance, enhance stress resilience, and promote sustainable agriculture. Full article

The maritime sector, responsible for approximately 3% of global greenhouse gas (GHG) emissions, is under growing pressure to transition toward climate-neutral operations. Significant progress has been made in developing sustainable fuels and propulsion systems to meet these demands. Although electric propulsion and fuel cells are highlighted as key technologies for achieving net-zero carbon targets, they remain an immature solution for large-scale maritime use, particularly in long-distance shipping. Therefore, modifying internal combustion engines and employing alternative fuels emerge as more feasible transition strategies, especially in short-sea shipping and port applications such as tugboat operations. Among alternative fuels, hydrogen (H₂) and ammonia (NH₃) have emerged as the most prominent fuels in recent years due to their carbon-free nature and compatibility with existing marine compression ignition (CI) engines with only minor modifications. This study explores the viability of hydrogen and ammonia as alternative fuels for CI engines in terms of technological, economic, and environmental aspects. Also, using a life cycle assessment (LCA) framework, this study examines the environmental impacts and feasibility of gray, blue, and green hydrogen and ammonia production pathways. The analysis is conducted from both well-to-tank (WtT) and tank-to-wake (TtW) perspectives. The results demonstrate that green fuel production pathways significantly reduce emissions but lead to higher economic costs, while intermediate blends offer a balanced trade-off between environmental and financial performance. Moreover, the combustion stage analysis indicates that H₂ and NH₃ provide substantial environmental benefits by significantly reducing harmful emissions. Consequently, a Multi-Criteria Decision Making (MCDM) approach is employed to determine the optimal blending strategy, revealing that a 24% hydrogen and 76% marine diesel oil (MDO) energy share yields the most favorable outcome among the evaluated alternatives. Full article

Developing bifunctional electrocatalysts that simultaneously enable green hydrogen production and water purification is essential for advancing sustainable energy and environmental technologies. In this study, we present Cu@Pd core–shell nanostructures fabricated through template-assisted electrodeposition of Cu, followed by galvanic Pd modification on pyrolytic graphite electrodes (PGEs). The optimised catalyst exhibited superior hydrogen evolution reaction (HER) activity, with an onset potential of 70 mV, a low Tafel slope of 33 mV dec⁻¹ and excellent stability during prolonged HER operation. In addition to hydrogen evolution, Cu@Pd/PGE shows significantly enhanced nitrate reduction reaction (NRR) activity compared to Cu/PGE in both alkaline and neutral conditions. Under ideal conditions, the catalyst achieved 60% nitrate removal with high selectivity towards ammonia and minimal nitrite formation, emphasising its superior performance. This enhanced bifunctionality arises from the synergistic Cu–Pd interface, facilitating efficient nitrate adsorption and selective hydrogenation. Despite their high catalytic activity for both HER and NRR, the Cu@Pd nanostructures could often emerge as a versatile platform for integration into sustainable hydrogen production and an effective denitrification process. Full article

The rapid development of marine recirculating aquaculture systems (RASs) worldwide offers an efficient and sustainable approach to aquaculture. However, the slow start-up of the nitrification process under low-temperature conditions remains a significant challenge. This study evaluated multiple start-up strategies for moving bed biofilm reactors (MBBRs) operating at 13–15 °C. Among them, the salinity-gradient (SG) strategy exhibited the best performance, reducing the start-up time by 38 days compared to the control, with microbial richness (Chao1 index) reaching 396 and diversity (Shannon index) of 4.89. Inoculation with mature biofilm (MBI) also showed excellent results, shortening the start-up period by 26 days and achieving a stable total ammonia nitrogen (TAN) effluent concentration below 0.5 mg/L within 132 days. MBI exhibited the highest microbial richness (Chao1 index = 808) and diversity (Shannon index = 5.55), significantly higher than those of the control (Chao1 index = 279, Shannon index = 3.90) and other treatments. The hydraulic retention time-gradient (HRT) strategy contributed to performance improvement as well, with a 24-day reduction in start-up time and a Chao1 index of 663 and a Shannon index is 4.69. In contrast, nitrifying bacteria addition (NBA) and carrier adhesion layer modification (CALM) had limited effects on start-up efficiency or microbial diversity, with Chao1 indices of only 255 and 228, and Shannon indices were both 3.24, respectively. Overall, the results indicate that salinity acclimation, mature biofilm inoculation, and extended HRT are effective approaches for promoting microbial community adaptation and enhancing MBBR start-up under low-temperature marine conditions. Full article

Polyethersulfone (PES) is one of the most used synthetic polymers for the production of hemodialysis membranes, due to its appropriate features, such as biocompatibility, high permeability for low-molecular-weight proteins, high endotoxin retention ability, and resistance to sterilization processes. However, there is room for improvement regarding their anticoagulant properties when coming into contact with blood. In the present study, commercial PES membranes were plasma-treated and then chemically modified with crown ether, an organic compound that could interfere with the coagulation cascade by complexating Ca²⁺ in the blood. The physico-chemical and morphological characteristics of the membranes were determined by FT-IR, XPS, TGA, SEM, and CT analyses, while their efficiency in retaining calcium ions was evaluated via ICP-MS. The results revealed that plasma treatment with a mixture of argon and ammonia was the most effective in generating nitrogen-containing surface functional groups and that these moieties can be successfully used for the covalent functionalization of the membranes. Also, the Ca²⁺ retention ability of the PES membranes was improved by up to 30% after chemical modification with 4′-aminobenzo-15-crown-5 ether. Full article

To address severe ammonia gas and dust pollution coupled with resource waste in exhaust gases from urea prilling towers, a production process for gasified biochar-based slow-release fertilizer is proposed to achieve resource recovery of exhaust pollutants. Through phosphoric acid impregnation modification applied to gasified biochar, its ammonia gas adsorption capacity was significantly enhanced, with saturated adsorption capacity increasing from 0.61 mg/g (unmodified) to 32 mg/g. Coupled with the tower-top bag filter, the modified biochar combines with ammonia gas and urea dust in exhaust gases, subsequently forming biochar-based slow-release fertilizer through dehydration and granulation processes. Material balance analysis demonstrates that a single 400,000-ton/year urea prilling tower achieves a daily fertilizer production capacity of 55 tons, with 18% active ingredient content. The nitrogen content can be upgraded to national standards through urea supplementation. Economic analysis demonstrates a total capital investment of USD1.2 million, with an annual net profit of USD0.88 million and a static payback period of 1.36 years. This process not only achieves ammonia gas emission reduction but also converts waste biochar into high-value fertilizer. It displays dual advantages of environmental benefits and economic feasibility and provides an innovative solution for resource utilization of the exhaust gases from the urea prilling process. Full article

Electroless silver (Ag) plating has emerged as a simple yet effective surface modification technique, garnering significant attention in consumer electronics and composite materials. This study systematically investigates the influence of glucose dosage on the microstructural refinement of Ag coatings deposited from silver–ammonia solutions onto iron (Fe) particles while also evaluating the oxidation resistance of Ag-plated particles through thermogravimetric analysis. Optimal results were achieved at a silver nitrate concentration of 0.02 mol/L and a glucose concentration of 0.05 mol/L, producing Fe particles with a uniform and dense silver coating featuring an average Ag grain size of 76 nm. The moderate excess glucose played a dual role: facilitating Ag⁺ ion reduction while simultaneously inhibiting the growth of Ag atomic clusters, thereby ensuring microstructural refinement of the silver layer. Notably, the Ag-plated particles demonstrated superior oxidation resistance compared to their uncoated counterparts. These findings highlight the significance of fine-grained electroless Ag plating in developing high-temperature conductive metal particles and optimizing interfacial structures in composite materials. Full article

The recirculating aquaculture system (RAS) has been rapidly adopted worldwide in recent years due to its high productivity, good stability, and good environmental controllability (and therefore friendliness to environment and ecology). Nevertheless, the effluent from seawater RAS contains a high level of ammonia nitrogen which is toxic to fish, so it is necessary to overcome the salinity conditions to achieve rapid and efficient nitrification for recycling. The moving bed biofilm reactor (MBBR) has been widely applied often by using PE fillers for efficient wastewater treatment. However, the start-up of MBBR in seawater environments has remained a challenge due to salinity stress and harsh inoculation conditions. This study investigated a new PE-filler surface modification method towards the enhanced start-up of mariculture MBBR by combining liquid-phase oxidation and maifanstone powder. The aim was to obtain a higher porous surface and roughness and a strong adsorption and alkalinity adjustment for the MBBR PE filler. The hydrophilic properties, surface morphology, and chemical structure of a raw polyethylene filler (an unmodified PE filler), liquid-phase oxidation modified filler (LO-PE), and liquid-phase oxidation combined with a coating of a maifanstone-powder-surface-modified filler (LO-SCPE) were first investigated and compared. The results showed that the contact angle was reduced to 45.5° after the optimal liquid-phase oxidation modification for LO-PE, 49.8% lower than that before modification, while SEM showed increased roughness and surface area by modification. Moreover, EDS presented the relative content of carbon (22.75%) and oxygen (42.36%) on the LO-SCPE surface with an O/C ratio of 186.10%, which is 177.7% higher than that of the unmodified filler. The start-up experiment on MBBRs treating simulated marine RAS wastewater (HRT = 24 h) showed that the start-up period was shortened by 10 days for LO-SCPE compared to the PE reactor, with better ammonia nitrogen removal observed for LO-SCPE (95.8%) than the PE reactor (91.7%). Meanwhile, the bacterial community composition showed that the LO-SCPE reactor had a more diverse and abundant AOB and NOB. The Nitrospira has a more significant impact on nitrification because it would directly oxidize NH₄⁺-N to NO₃⁻-N (comammox pathway) as mediated by AOB and NOB. Further, the LO-SCPE reactor showed a higher NH₄⁺-N removal rate (>99%), less NO₂⁻-N accumulation, and a shorter adaption period than the PE reactor. Eventually, the NH₄⁺-N concentrations of the three reactors (R1, R2, and R3) reached <0.1 mg/L within 3 days, and their NH₄⁺-N removal efficiencies achieved 99.53%, 99.61%, and 99.69%, respectively, under ammonia shock load. Hence, the LO-SCPE media have a higher marine wastewater treatment efficiency. Full article