The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform

Dae Ryook Yang - One of the best experts on this subject based on the ideXlab platform.

  • mathematical model of flat sheet membrane Modules for fo process plate and frame Module and spiral wound Module
    Journal of Membrane Science, 2011
    Co-Authors: Boram Gu, Dae Ryook Yang
    Abstract:

    Abstract The forward osmosis process is considered a promising desalination method due to its low energy requirement compared to other methods. In this study, modelling and simulations for a Plate-and-Frame and a modified spiral-wound Module are carried out for the FO process. The mathematical models consist of mass balance, a permeate flux model, and concentration polarization equations. The Plate-and-Frame model is formulated with consideration of flow directions, and the modified spiral-wound model is formulated with consideration of its geometric characteristics. These two sets of model equations are numerically and iteratively integrated since they are implicit and highly non-linear. The simulation for both Modules was conducted by varying 4 types of operating conditions: volumetric flow rate of the feed and the draw solution, the concentration of the draw solution, flow direction, and the membrane orientation. The results for various conditions are also compared. In future research, the developed model could be applied for designing FO Modules and finding optimal operating conditions.

Maria A M Reis - One of the best experts on this subject based on the ideXlab platform.

  • validation of the ion exchange membrane bioreactor concept in a plate and frame Module configuration
    Process Biochemistry, 2012
    Co-Authors: Ana R Ricardo, Svetlozar Velizarov, Joao G Crespo, Maria A M Reis
    Abstract:

    Abstract The ion exchange membrane bioreactor (IEMB) is a particular case of a membrane-supported biofilm reactor, in which oxy-anions, used as electron acceptors by an anoxic mixed microbial culture, are removed from a polluted water stream through an anion-exchange membrane. The opposite side of this membrane is used for the development of a biofilm, contacting a biocompartment, to which nutrients and chloride are fed as a source of “driving” counter-ion. The applicability of a Plate-and-Frame IEMB Module configuration, consisting of a series of membranes, for the treatment of drinking water contaminated with nitrate and perchlorate, was evaluated. Permeation of carbon source across the membrane to the treated water stream was avoided by a dedicated start-up procedure involving a gradual increase of ethanol feeding to the IEMB biocompartment. It was demonstrated that the biocompartment pH must be controlled not only to guarantee a complete perchlorate removal, but also to avoid precipitation of struvite on the membrane surface, which provokes membrane scaling and decreases the availability of nutrients for the biofilm. Under these conditions, the IEMB was successfully operated maintaining both nitrate and perchlorate concentrations in the treated water below their recommended levels for drinking water supplies.

Boram Gu - One of the best experts on this subject based on the ideXlab platform.

  • mathematical model of flat sheet membrane Modules for fo process plate and frame Module and spiral wound Module
    Journal of Membrane Science, 2011
    Co-Authors: Boram Gu, Dae Ryook Yang
    Abstract:

    Abstract The forward osmosis process is considered a promising desalination method due to its low energy requirement compared to other methods. In this study, modelling and simulations for a Plate-and-Frame and a modified spiral-wound Module are carried out for the FO process. The mathematical models consist of mass balance, a permeate flux model, and concentration polarization equations. The Plate-and-Frame model is formulated with consideration of flow directions, and the modified spiral-wound model is formulated with consideration of its geometric characteristics. These two sets of model equations are numerically and iteratively integrated since they are implicit and highly non-linear. The simulation for both Modules was conducted by varying 4 types of operating conditions: volumetric flow rate of the feed and the draw solution, the concentration of the draw solution, flow direction, and the membrane orientation. The results for various conditions are also compared. In future research, the developed model could be applied for designing FO Modules and finding optimal operating conditions.

Joao G Crespo - One of the best experts on this subject based on the ideXlab platform.

  • validation of the ion exchange membrane bioreactor concept in a plate and frame Module configuration
    Process Biochemistry, 2012
    Co-Authors: Ana R Ricardo, Svetlozar Velizarov, Joao G Crespo, Maria A M Reis
    Abstract:

    Abstract The ion exchange membrane bioreactor (IEMB) is a particular case of a membrane-supported biofilm reactor, in which oxy-anions, used as electron acceptors by an anoxic mixed microbial culture, are removed from a polluted water stream through an anion-exchange membrane. The opposite side of this membrane is used for the development of a biofilm, contacting a biocompartment, to which nutrients and chloride are fed as a source of “driving” counter-ion. The applicability of a Plate-and-Frame IEMB Module configuration, consisting of a series of membranes, for the treatment of drinking water contaminated with nitrate and perchlorate, was evaluated. Permeation of carbon source across the membrane to the treated water stream was avoided by a dedicated start-up procedure involving a gradual increase of ethanol feeding to the IEMB biocompartment. It was demonstrated that the biocompartment pH must be controlled not only to guarantee a complete perchlorate removal, but also to avoid precipitation of struvite on the membrane surface, which provokes membrane scaling and decreases the availability of nutrients for the biofilm. Under these conditions, the IEMB was successfully operated maintaining both nitrate and perchlorate concentrations in the treated water below their recommended levels for drinking water supplies.

  • membrane based solvent extraction and stripping of lactate in hollow fibre contactors
    Journal of Membrane Science, 1997
    Co-Authors: Isabel M Coelhoso, Joao G Crespo, P Silvestre, R M C Viegas, Manuel J T Carrondo
    Abstract:

    This work reports lactate extraction with Aliquat 336, an ion-exchange carrier, using membrane contactors with hydrophobic microporous membranes. The overall mass-transfer coefficients were evaluated by either assuming a constant distribution coefficient or using the equilibrium equation. The mass-transfer coefficients calculated using the equilibrium relationship between Cf∗ and CO, proved to be more rigorous, since the variation of the distribution coefficient with solute concentration is accounted for throughout the extraction process. Assuming the resistance in series model, the membrane resistance was identified as the limiting step on the mass-transfer process. In order to increase the membrane mass-transfer coefficient, it is necessary to increase the diffusion coefficient of the lactate-amine complex; this can be achieved by reducing the viscosity of the organic phase either through a temperature increase or reduction of the carrier concentration. Using a Plate-and-Frame Module with a well-defined hydrodynamic characterization of both phases, the mass-transfer coefficients can be rigorously evaluated; these were compared with the values obtained with hollow-fibre Modules. Simultaneous extraction and stripping of lactate was accomplished using two hollow-fibre Modules in series. This configuration assures that saturation of the carrier does not occur, as it is permanently regenerated; furthermore, the carrier concentration can be reduced while still maintaining the mass-transfer rate, thus decreasing the associated operating costs of the process.

Ana R Ricardo - One of the best experts on this subject based on the ideXlab platform.

  • validation of the ion exchange membrane bioreactor concept in a plate and frame Module configuration
    Process Biochemistry, 2012
    Co-Authors: Ana R Ricardo, Svetlozar Velizarov, Joao G Crespo, Maria A M Reis
    Abstract:

    Abstract The ion exchange membrane bioreactor (IEMB) is a particular case of a membrane-supported biofilm reactor, in which oxy-anions, used as electron acceptors by an anoxic mixed microbial culture, are removed from a polluted water stream through an anion-exchange membrane. The opposite side of this membrane is used for the development of a biofilm, contacting a biocompartment, to which nutrients and chloride are fed as a source of “driving” counter-ion. The applicability of a Plate-and-Frame IEMB Module configuration, consisting of a series of membranes, for the treatment of drinking water contaminated with nitrate and perchlorate, was evaluated. Permeation of carbon source across the membrane to the treated water stream was avoided by a dedicated start-up procedure involving a gradual increase of ethanol feeding to the IEMB biocompartment. It was demonstrated that the biocompartment pH must be controlled not only to guarantee a complete perchlorate removal, but also to avoid precipitation of struvite on the membrane surface, which provokes membrane scaling and decreases the availability of nutrients for the biofilm. Under these conditions, the IEMB was successfully operated maintaining both nitrate and perchlorate concentrations in the treated water below their recommended levels for drinking water supplies.