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Your search keyword '"N-nitrosamine"' showing total 4 results
Start Over Descriptor "N-nitrosamine" Journal water research
4 results on '"N-nitrosamine"'

1. Role of absorber and desorber units and operational conditions for N-nitrosamine formation during amine-based carbon capture

Author

William A. Mitch, Zimeng Wang, and Zhong Zhang

Subjects
Flue gas, Nitrosamines, Environmental Engineering, 0208 environmental biotechnology, 02 engineering and technology, 010501 environmental sciences, 01 natural sciences, chemistry.chemical_compound, Amines, Nitrite, Waste Management and Disposal, Nitrites, NOx, 0105 earth and related environmental sciences, Water Science and Technology, Civil and Structural Engineering, N-nitrosamine, Ecological Modeling, Thermal decomposition, Carbon Dioxide, Pollution, Carbon, 020801 environmental engineering, Solvent, Piperazine, chemistry, Chemical engineering, Amine gas treating
Abstract

The formation of carcinogenic N-nitrosamines from reactions between solvent amines and flue gas NOx is an important concern for the application of amine-based processes to capture CO2 post-combustion. Using an advanced test rig with interconnected absorber and desorber units, we evaluated the importance for N-nitrosamine formation of the desorber relative to the absorber, and any synergism between the two units. Variations in desorber temperature and in flue gas composition indicated that N-nitrosamine formation from fresh monoethanolamine (MEA) occurred predominantly in the absorber. N-nitrosamine formation was driven by high NO2 and O2 flue gas concentrations, although NO also contributed. In contrast, N-nitrosamine formation from piperazine (PZ) was driven by reactions with nitrite in the heated desorber, and accelerated concurrent with nitrite accumulation. A complementary experiment simulating aged MEA solvent (high nitrite, 1.5% sarcosine as a proxy of secondary amine degradation products) suggested the desorber becomes an order of magnitude more important than the absorber for N-nitrosamine formation. For fresh MEA solvent, increasing the desorber temperature from 110 °C to 130 °C promoted thermal decomposition of N-nitrosamines, reducing N-nitrosamine accumulation rates two-fold. Compared to the test rig, the prevailing practice of using separate absorber columns and autoclave-like treatments to mimic desorber units predicted the direction, but underestimated the magnitude of N-nitrosamine formation. Because N-nitrosamine accumulation rates are the net result of competing formation and thermal decomposition processes, use of continuously cycling test rigs may be necessary to understand the impacts of different operating conditions.

Published
2020
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2. Nitric oxide reactivity accounts for N-nitroso-ciprofloxacin formation under nitrate-reducing conditions.

Author

Brienza, Monica, Manasfi, Rayana, Sauvêtre, Andrés, and Chiron, Serge

Subjects
*RADICAL anions, *NITRIC oxide, *SEWAGE disposal plants, *SECONDARY amines, *SUPEROXIDE dismutase, *MASS spectrometry, *SUPEROXIDES
Abstract

• N-nitroso-CIP was formed and accumulated in sludge under denitrifying conditions. • The percentage of transformation of CIP into N-nitroso-CIP reached 14.3%. • NO release and codenitrification were responsible for N-nitroso-CIP formation. • Formation of carbamate adducts in presence of HCO 3 − inhibited nitrosation reaction. • N-nitroso-CIP and N-nitroso-hydrochlorothiazide were identified in WWTP effluents. The formation of N-nitroso-ciprofloxacin (CIP) was investigated both in wastewater treatment plants including nitrification/denitrification stages and in sludge slurry experiments under denitrifying conditions. The analysis of biological wastewater treatment plant effluents by Kendrick mass defect analysis and liquid chromatography - high resolution - mass spectrometry (LC HRMS) revealed the occurrence of N-nitroso-CIP and N-nitroso-hydrochlorothiazide at concentration levels of 34 ± 3 ng/L and 71 ± 6 ng/L, respectively. In laboratory experiments and dark conditions, produced N-nitroso-CIP concentrations reached a plateau during the course of biodegradation experiments. A mass balance was achieved after identification and quantification of several transformation products by LC HRMS. N-nitroso-CIP accounted for 14.3% of the initial CIP concentration (20 µg/L) and accumulated against time. The use of 4,5-diaminofluorescein diacetate and superoxide dismutase as scavengers for in situ production of nitric oxide and superoxide radical anion respectively, revealed that the mechanisms of formation of N-nitroso-CIP likely involved a nitrosation pathway through the formation of peroxynitrite and another one through codenitrification processes, even though the former one appeared to be prevalent. This work extended the possible sources of N-nitrosamines by including a formation pathway relying on nitric oxide reactivity with secondary amines under activated sludge treatment. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Published
2020
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3. N-nitrosamine rejection by reverse osmosis membranes: a full-scale study

Author

Takahiro Fujioka, Jörg E. Drewes, Yvan Poussade, James A. McDonald, Long D. Nghiem, Stuart J. Khan, and Annalie Roux

Subjects
Osmosis, Environmental Engineering, Chromatography, Nitrosamines, N-nitrosamine, Chemistry, Ecological Modeling, Membrane fouling, Membranes, Artificial, Permeation, Pollution, Feed temperature, law.invention, Water Purification, Membrane, law, Reverse osmosis, Waste Management and Disposal, Filtration, Water Science and Technology, Civil and Structural Engineering
Abstract

This study aims to provide longitudinal and spatial insights to the rejection of N-nitrosamines by reverse osmosis (RO) membranes during sampling campaigns at three full-scale water recycling plants. Samples were collected at all individual filtration stages as well as at a cool and a warm weather period to elucidate the impact of recovery and feed temperature on the rejection of N-nitrosamines. N-nitrosodimethylamine (NDMA) was detected in all RO feed samples varying between 7 and 32 ng/L. Concentrations of most other N-nitrosamines in the feed solutions were determined to be lower than their detection limits (3–5 ng/L) but higher concentrations were detected in the feed after each filtration stage. As a notable exception, in one plant, N-nitrosomorpholine (NMOR) was observed at high concentrations in RO feed (177–475 ng/L) and permeate (34–76 ng/L). Overall rejection of NDMA among the three RO systems varied widely from 4 to 47%. Data presented here suggest that the feed temperature can influence rejection of NDMA. A considerable variation in NDMA rejection across the three RO stages (14–78%) was also observed. Overall NMOR rejections were consistently high ranging from 81 to 84%. On the other hand, overall rejection of N-nitrosodiethylamine (NDEA) varied from negligible to 53%, which was considerably lower than values reported in previous laboratory-scale studies. A comparison between results reported here and the literature indicates that there can be some discrepancy in N-nitrosamine rejection data between laboratory- and full-scale studies probably due to differences in water recoveries and operating conditions (e.g. temperature, membrane fouling, and hydraulic conditions).

Published
2013

4. Fate of NDMA precursors through an MBR-NF pilot plant for urban wastewater reclamation and the effect of changing aeration conditions.

Author

Mamo J, Insa S, Monclús H, Rodríguez-Roda I, Comas J, Barceló D, and Farré MJ

Subjects
Bioreactors, Membranes, Artificial, Nitrification, Waste Disposal, Fluid, Water Purification, Dimethylnitrosamine, Wastewater
Abstract

The removal of N-nitrosodimethylamine (NDMA) formation potential through a membrane bioreactor (MBR) coupled to a nanofiltration (NF) pilot plant that treats urban wastewater is investigated. The results are compared to the fate of the individual NDMA precursors detected: azithromycin, citalopram, erythromycin, clarithromycin, ranitidine, venlafaxine and its metabolite o-desmethylvenlafaxine. Specifically, the effect of dissolved oxygen in the aerobic chamber of the MBR pilot plant on the removal of NDMA formation potential (FP) and individual precursors is studied. During normal aerobic operation, implying a fully nitrifying system, the MBR was able to reduce NDMA precursors above 94%, however this removal percentage was reduced to values as low as 72% when changing the conditions to minimize nitrification. Removal decreased also for azithromycin (68-59%), citalopram (31-17%), venlafaxine (35-15%) and erythromycin (61-16%) on average during nitrifying versus non-nitrifying conditions. The removal of clarithromycin, o-desmethylvenlafaxine and ranitidine could not be correlated with the nitrification inhibition, as it varied greatly during the experiment time. The MBR pilot plant is coupled to a nanofiltration (NF) system and the results on the rejection of both, NDMA FP and individual precursors, through this system was above 90%. Finally, results obtained for the MBR pilot plant are compared to the percentage of removal by a conventional full scale biological wastewater treatment plant (WWTP) fed with the same influent. During aerobic operation, the removal of NDMA FP by the MBR pilot plant was similar to the full scale WWTP., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Published
2016
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