Direct nanofiltration treatment using flat-sheet membrane modules reconfigured from spiral-wound elements

Water treatment using a nanofiltration (NF) membrane is an effective advanced water treatment process for achieving high organics removal. This presentation will cover our recent studies examining the feasibility of direct (i.e., no pre-treatment) NF treatment of surface water and wastewater using a submerged flat-sheet NF membrane module. When a direct NF system was employed for surface water treatment, we observed only slight membrane fouling over three months. The separation performance of the NF system remained high: total organic carbon (TOC) removal remained at 80-90% in most sampling occasions. Membrane surface characterization revealed that many substances covered the membrane surface. It was speculated that these substances deposited on the membrane surface provide a small contribution to the hydraulic resistance. Further, the membrane foulant was readily removed by physical cleaning, and the permeability fully recovered. This indicates that the membrane foulant did not penetrate the pores of the NF membrane. The results attained through the on-site test suggest the viability of direct NF treatment of surface water for achieving high water quality and stable system operation. In addition to the drinking water treatment, the presentation will provide the results of applying the direct NF system for wastewater treatment.

The efficiency of CO2 capture using a hollow fiber membrane containing 2-(2-Aminoethylamino) ethanol (AEEA) from the emission gas in the Integrated Gasification Combined Cycle (IGCC) was investigated by density functional theory and fluid dynamics. A reaction path for CO2 sorption to AEEA involving two H2O molecules with three – proton transfer was found to give the low barrier of the reaction due to 6 intermolecular hydrogen bonds which make the transition state structure more stable. The activation energy in the reaction path for CO2 sorption to AEEA was 7.11 kcalmol−1 which is approximately 10 kcalmol−1 lower than that involving one H2O molecule with two – proton transfer discussed in our previous study (Higashino et al., 2023). Since the activation energy is much lower than those in the other reaction paths we have investigated, it can occur much more frequently than others when sufficient moisture is maintained in the membrane. The estimated reaction rate k = 3.407 × 108 s−1 indicates that CO2 becomes carbamate by reaction with AEEA as soon as reaching the surface of the membrane, and thus, CO2 attachment to AEEA cannot be the rate limiting. Since flow in the hollow fiber membrane can be laminar, simulated CO2 permeance for the temperature of 358 K and the pressure of 2.4 MPa has a range from 10−10 to 10−9 m3 (STP) m−2s−1Pa−1, which is a few orders smaller than that for the flat sheet membrane, flow over which is turbulent, i.e.10−8 to 10−7 m3(STP) m−2s−1Pa−1 (Higashino et al., 2023). Overall, the reaction rate of CO2 attachment to AEEA is sufficiently large, and hence, any one of mass transfer of CO2 induced by turbulence (turbulent flow), molecular diffusion of CO2 from feed gas to the membrane surface (laminar flow), and molecular diffusion of bicarbonate (HCO3-) from the feed side to the permeate side in the membrane can be the rate limiting depending on which type of membrane, e.g. a flat sheet membrane module, a spiral membrane module, a hollow fiber membrane contactor, etc., is used for CO2 capture.

Influence of surface hydrophilicity on polytetrafluoroethylene flat sheet membrane fouling in a submerged membrane bioreactor using two activated sludges with different characteristics

Mathematical modelling and numerical simulation of CO2/CH4 separation in a polymeric membrane

Membrane fouling mitigation in dairy wastewater microfiltration was investigated through air back pulsing. Flat sheet membrane module with pore size of 0.1 mm was used. The model dairy wastewater was prepared by skim milk diluted with distilled water (milk:water = 1:2). The effect of three parameters, including air back pulsing pressure (pb), back pulsing frequency (f), and back pulsing duration (d) on fouling control was investigated. It was found that high pressures of air in short durations of back pulsing can improve the filtration process and result in higher amounts of permeate. However, it is anticipated that beyond the region of study, very high frequency would not be helpful. Very high frequencies mean short back pulsing durations, and this might result in loss of positive effect of back pulsing. The maximum permeate amount obtained using back pulsing assisted filtration process was 83% higher than the one obtained without back pulsing.

Improving gas separation properties of polymeric membranes based on glassy polymers by gas phase fluorination

Catalytic conversion of CO2 to biofuel (methanol) and downstream separation in membrane-integrated photoreactor system under suitable conditions

Direct nanofiltration of surface water using capillary membranes: comparison with flat sheet membranes

Improved performance of gravity-driven membrane filtration for seawater pretreatment: Implications of membrane module configuration

The paper evaluates the results of obtained data from 2 years of observation of real household wastewater treatment plant (WWTP) with immersed membrane module. Two different commercial flat sheet membrane modules were investigated. The membrane modules, as well as whole WWTP, were tested with different fluxes and moreover the response of membrane and activated sludge to different conditions like real peak wastewater flows, extremes temperatures (winter below 5°C) and high pH values.

The effect of a non-woven scrim at the surface of a flat-sheet, microporous membrane on gas–liquid mass transfer

Chemistry in a spinneret – Formation of hollow fiber membranes with a cross-linked polyelectrolyte separation layer

Vacuum enhanced direct contact membrane distillation for oil field produced water desalination: specific energy consumption and energy efficiency

An advanced treatment of high-strength opium alkaloid processing industry wastewaters with membrane technology: pretreatment, fouling and retention characteristics of membranes