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Nitrate (NO) contamination has become a significant global environmental issue. Traditional nitrate reduction processes typically require external pH control to maintain neutral conditions and prevent nitrite accumulation. In this study, a hydrogen-based membrane biofilm reactor (H-MBfR) was constructed without external pH regulation. The reactor relied on the alkalinity generated by the nitrate reduction process itself, maintaining a highly alkaline environment with stable denitrification and up to 60% ammonium conversion at pH levels reaching 11.70. The DNRA process was found to be independent of substrate type, inversely proportional to electron supply, and exhibited the highest reaction rate at pH 11, as confirmed by both ex-situ and in-situ batch experiments. Microbial community analysis indicated that Meiothermus was the predominant genus within the biofilm. This research reveals a novel nitrogen transformation phenomenon, demonstrating the coexistence of DNRA and denitrification processes under high alkalinity conditions in the H-MBfR system. These findings offer new insights into nitrate reduction processes and suggest potential advancements in wastewater treatment and resource recovery.
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http://dx.doi.org/10.1016/j.chemosphere.2024.143705 | DOI Listing |
ACS Appl Mater Interfaces
September 2025
Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand.
The accumulation of nitrate (NO) from agricultural runoff poses a growing threat to ecosystems and public health. Converting nitrate into ammonia (NH) through the electrochemical nitrate reduction reaction (NORR) offers a promising strategy to mitigate environmental contamination while creating a sustainable circular route to fertilizer production. However, achieving high NH production and energy efficiency remains challenging.
View Article and Find Full Text PDFJ Colloid Interface Sci
September 2025
School of Physics and Materials Science, Nanchang University, 999 Xuefu Road, Honggutan District, Nanchang, Jiangxi 330031, China; College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, PR China. Electronic address:
MXenes represent exceptionally promising electrocatalytic materials for ammonia synthesis, owing to their outstanding electrical conductivity, modifiable surface functional groups, exceptional hydrophilicity, high specific surface area, and electronegative surface characteristics. In this investigation, we systematically demonstrate that the persistent challenge of Cu and Co nanoparticle agglomeration can be effectively addressed through the in-situ growth of bimetallic CuCo nanoparticles on TiCTMXene nanosheets. This innovative approach significantly enlarges the electrochemically active surface area, maximizes the exposure of catalytically active sites, and optimizes mass transport properties, consequently leading to substantially enhanced electrocatalytic performance for ammonia synthesis.
View Article and Find Full Text PDFWater Res
September 2025
Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China. Electronic address:
The differentiation of the nitrate reduction pathway is of great significance in the ecosystem, as it determines the occurrence form of ecosystem N. In order to explore the impact and mechanism of different algal dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) on differentiation of nitrate (NO-N) reduction pathway, small-scale enclosure experiment was conducted to analyze the DON and DOP composition, nutrient level, microbial community composition and NO-N reduction pathway in ponds with Microcystis and Dolichospermum blooms. The main DON produced by Microcystis included lipids and proteins as well as carbohydrate which were readily degradable, whereas the DOP produced by Dolichospermum predominantly consists of readily degradable forms such as carbohydrate and protein.
View Article and Find Full Text PDFAnaerobic methanotrophic archaea (ANME) are crucial to planetary carbon cycling. They oxidise methane in anoxic niches by transferring electrons to nitrate, metal oxides, or sulfate-reducing bacteria. No ANMEs have been isolated, hampering the biochemical investigation of anaerobic methane oxidation.
View Article and Find Full Text PDFSmall
September 2025
School of Nanoscience and Materials Engineering, Henan University, Zhengzhou, 450046, China.
Ru/RuOx/CNTs heterostructured materials are synthesized using an in situ method. The Ru─RuOx heterostructure facilitates active hydrogen dissociation, leading to excellent catalytic performance in nitrate reduction, with ammonia as the primary product at low overpotentials. The process achieves Faradaic efficiencies of ammonia exceeding 90% and a production rate of 1.
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