The anaerobic digester is a vital component in a zero-discharge mariculture system as therein most of the organic matter is mineralized and nitrogen-containing compounds are converted to gaseous N(2). Although denitrification is a major respiratory process in this nitrate-rich treatment stage, also sulfate respiration takes place and may cause undesirable high sulfide concentrations in the effluent water. To examine the effect of sulfide on nitrate reduction, in situ depth profiles of inorganic nitrogen and sulfur compounds were determined. Additionally, nitrate reduction was examined as a function of ambient sulfide concentrations in sludge collected from different locations in the anaerobic reactor. Depth profiles showed high concentrations of nitrate and low concentrations of sulfide and ammonia in the aqueous layer of the reactor. A sharp decrease of nitrate and an increase in sulfide and ammonia concentrations was measured at the water-sludge interface. Nitrate reduction was highest in this interface zone with rates of up to 8.05+/-0.57 micromol NO(3)(-)h(-1)g((sludge))(-1). Addition of sulfide increased the nitrate reduction rate at all sludge depths, pointing to the important role of autotrophic denitrification in the anaerobic reactor. Dissimilatory nitrate reduction to ammonia (DNRA) was found to be low in all sludge layers but was enhanced when sludge was incubated at high sulfide concentrations. Although nitrate reduction rates increased as a result of sulfide addition to sludge samples, no differences in nitrate reduction rates were observed between the samples incubated with different initial sulfide concentrations. This as opposed to sulfide oxidation rates, which followed Michaelis-Menten enzymatic kinetics. Partial oxidation of sulfide to elemental sulfur instead of a complete oxidation to sulfate, could explain the observed patterns of nitrate reduction and sulfide oxidation in sludge incubated with different initial sulfide concentrations.
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http://dx.doi.org/10.1016/j.watres.2008.07.031 | DOI Listing |
Nat Commun
December 2024
School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China.
Electrochemical nitrate reduction reaction offers a sustainable and efficient pathway for ammonia synthesis. Maintaining satisfactory Faradaic efficiency for long-term nitrate reduction under ampere-level current density remains challenging due to the inevitable hydrogen evolution, particularly in pure nitrate solutions. Herein, we present the application of electron deficiency of Ru metals to boost the repelling effect of counter K ions via the electric-field-dependent synergy of interfacial water and cations, and thus largely promote nitrate reduction reaction with a high yield and well-maintained Faradaic efficiency under ampere-level current density.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
State Key Laboratory of Electrical Insulation and Power Equipment, Centre for Plasma Biomedicine, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
Liquid fertilizers, particularly when integrated with precision irrigation systems, offer a more efficient and sustainable alternative to traditional solid nitrogen fertilizers. The industrial production of ammonium nitrate (NHNO) is environmentally detrimental due to its reliance on fossil fuels. This study introduces an innovative air-to-NOx-to-NHNO pathway for synthesizing liquid nitrogen fertilizer.
View Article and Find Full Text PDFCJC Open
December 2024
University of British Columbia, Vancouver, British Columbia, Canada.
Background: Myocardial infarction with no obstructive coronary arteries (MINOCA), and ischemia with no obstructive coronary arteries (INOCA), are female-predominant conditions; clinical trials are lacking to guide medical management for the common underlying vasomotor etiologies. Data on long-term outcomes of (M)INOCA patients following attendance at a women's heart centre (WHC) are lacking.
Methods: Women diagnosed with MINOCA (n = 51) or INOCA (n = 112) were prospectively followed for 3 years at the Leslie Diamond WHC (LDWHC) in Vancouver.
Water Sci Technol
December 2024
Jiangsu Environmental Engineering Technology Co., Ltd, Nanjing 210000, China; Jiangsu Province Engineering Research Center of Synergistic Control of Pollution and Carbon Emissions in Key Industries, Nanjing 210000, China.
Moving bed biofilm reactors can purify urban domestic sewage through microbial biodegradation. High-throughput sequencing was used to study the response mechanism of the biofilm microbial community to temperature. The effluent quality of the reactor declined with the decrease in temperature.
View Article and Find Full Text PDFSci Rep
December 2024
Department of Earth and Planetary Sciences, University of California, Riverside, CA, 92521, USA.
The Salton Sea (SS), California's largest inland lake at 816 square kilometers, formed in 1905 from a levee breach in an area historically characterized by natural wet-dry cycles as Lake Cahuilla. Despite more than a century of untreated agricultural drainage inputs, there has not been a systematic assessment of nutrient loading, cycling, and associated ecological impacts at this iconic waterbody. The lake is now experiencing unprecedented degradation, particularly following the 2003 Quantification Settlement Agreement-the largest agricultural-to-urban water transfer in the United States.
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