Diffusional properties of methanogenic granular sludge: 1H NMR characterization
Fecha
2003Autor
Versión
Acceso abierto / Sarbide irekia
Tipo
Artículo / Artikulua
Versión
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 ...
[++]
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. [--]
Materias
Nuclear magnetic resonance (NMR),
Diffusional properties,
Methanogenic granular sludge
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).