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Membrane bioreactor for drinking water denitrification (1998)

Barreiros, A. M. ; Rodrigues, C. M. ; Crespo, J. P. S. G. ; [et al.]

Springer

Bioprocess engineering 18 (1998), S. 297-302

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ISSN: 0178-515X

Source: Springer Online Journal Archives 1860-2000

Topics: Process Engineering, Biotechnology, Nutrition Technology

Notes: Abstract The aim of this study is to evaluate the performance of a membrane bioreactor with cell recycle to be used for drinking water denitrification, when operated with a high nitrate load (up to 7.68 kgNO3 −/m3 day) and low hydraulic retention time (down to 0.625 h). Nitrate and nitrite were always completely removed for all the operational conditions used. The effluent's nitrite concentration kept below 0.1 mg NO2 −/l with exception of a short period, during the reactor start-up, when it accumulates. The performance of the membrane bioreactor was also evaluated using a groundwater containing 148 mg NO3 −/l. Nitrate and nitrite concentration in the effluent were below the recommended values for drinking water when the reactor was controlled at pH 7.0. The membrane flux decreases during operation as a consequence of membrane fouling. The flux decrease was more severe during operation with synthetic medium than with contaminated groundwater due to the existence of molecular complexes in the synthetic broth. A backshock technique was used to reduce the surface fouling of the membrane. Combining this technique with the use of a reserve asymmetric structured membrane it was found that the membrane flux remains nearly unchanged.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004490050445

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Modeling of immobilized cell reactor for propionic acid fermentation (1990)

Crespo, J. P. S. G. ; Almeida, J. S. ; Moura, M. J. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Biotechnology and Bioengineering 36 (1990), S. 705-716

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ISSN: 0006-3592

Keywords: Chemistry ; Biochemistry and Biotechnology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology

Notes: A mathematical model of steady state reactor behavior was developed, combining the tanks-in-series model with fermentation kinetic description. The model was tested with experimental data-from an immobilized cell reactor for propionic acid production operated under different residence times. In order to determine the effects of liquid flow rate and gas evolution on the degree of mixing, residence time distribution studies (RTDs) were performed during fermentation. The tanks-in-series model represented adequately the hydrodynamic behavior of the reactor. Association of an intrinsic kinetic model obtained from chemostat studies with the tanks-in-series model allows a “chemostat equivalent” cell concentration profile and a substrate consumption profile to be obtained. The advantage of having a two-level pH adjustment within the reactor is also discussed.

Additional Material: 9 Ill.