Diffusional properties of methanogenic granular sludge: 1H NMR characterization
Fecha
2003Autor
Versión
Acceso abierto / Sarbide irekia
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Artículo / Artikulua
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Versión publicada / Argitaratu den bertsioa
Impacto
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10.1128/aem.69.11.6644-6649.2003
Resumen
The diffusive properties of anaerobic methanogenic and sulfidogenic aggregates present in wastewater
treatment bioreactors were studied using diffusion analysis by relaxation time-separated pulsed-field gradient
nuclear magnetic resonance (NMR) spectroscopy and NMR imaging. NMR spectroscopy measurements were
performed at 22°C with 10 ml of granular sludge at a magnetic field strength of 0.5 T (20 ...
[++]
The diffusive properties of anaerobic methanogenic and sulfidogenic aggregates present in wastewater
treatment bioreactors were studied using diffusion analysis by relaxation time-separated pulsed-field gradient
nuclear magnetic resonance (NMR) spectroscopy and NMR imaging. NMR spectroscopy measurements were
performed at 22°C with 10 ml of granular sludge at a magnetic field strength of 0.5 T (20 MHz resonance
frequency for protons). Self-diffusion coefficients of H2O in the investigated series of mesophilic aggregates
were found to be 51 to 78% lower than the self-diffusion coefficient of free water. Interestingly, self-diffusion
coefficients of H2O were independent of the aggregate size for the size fractions investigated. Diffusional
transport occurred faster in aggregates growing under nutrient-rich conditions (e.g., the bottom of a reactor)
or at high (55°C) temperatures than in aggregates cultivated in nutrient-poor conditions or at low (10°C)
temperatures. Exposure of aggregates to 2.5% glutaraldehyde or heat (70 or 90°C for 30 min) modified the
diffusional transport up to 20%. In contrast, deactivation of aggregates by HgCl2 did not affect the H2O
self-diffusion coefficient in aggregates. Analysis of NMR images of a single aggregate shows that methanogenic
aggregates possess a spin-spin relaxation time and self-diffusion coefficient distribution, which are due to both
physical (porosity) and chemical (metal sulfide precipitates) factors. [--]
Editor
American Society for Microbiology
Publicado en
Applied and Environmental Microbiology, Nov. 2003, Vol. 69, No. 11, p. 6644–6649
Departamento
Universidad Pública de Navarra. Departamento de Producción Agraria /
Nafarroako Unibertsitate Publikoa. Nekazaritza Ekoizpena Saila
Versión del editor
Entidades Financiadoras
This research was supported by a TMR Marie Curie fellowship
(ERBFMBICT950250) and the Human Capital and Mobility EU Large
Scale Facility, Wageningen NMR Centre (ERBCHGECT940061).