Membrane modules vibrating

FIGURE 8.31 Schematic diagram of vibrating flat sheet membrane module. 

Al-akoum et al. experimentally and theoretically reported the flux enhancement in three particular systems shear-enhanced filtration with a vibrating membrane module, gas/liquid two-phase flows, and Dean vortices for yeast suspension system. They reported that the permeate flux was found to obey the empirical law J -- Twm (where Twm is the mean wall shear stress. Pa) with 0.43 < n < S7 and K depending on the membrane type and the yeast concentration for a particular system. 

Vibratory mechanism was one more interesting technique for reducing fouling negative effect. Vibrations can be apphed to flat sheet membrane modules, but many researchers tested the technique on performance of hollow fibers for different separation processes [3, 136]. One example of construction is shown in Fig. 9.10 [136] to assess the effect of axial membrane vibrations on mass transfer in a hollow fiber oxygenator. 

Akoum O, Jaffrin MY, Ding LH. Concentration of total milk proteins y high shear ultrafiltration in a vibrating membrane module. J. Membr. Sci. 2005 247 211-220. 

Ultrafiltration unit operations would benefit from increased mass transfer coefficients. In addition to improvements in membrane properties, module designs that reduce concentration polarization in the contacting fluid, such as the use of a rotating membrane [87] or module vibration [88], are needed. 

A bar that acts as a torsion spring connects the vibrating mass to a plate-and-frame membrane module that then vibrates... 

As an alternative to centrifugation, a vibrating membrane filter is used in some appheations such as yeast processes Pichia pastoris) and vaccine processes. Diatomaceous earth (DE) filtration is another potential alternative. Figure 14.11 Ulustrates DE embedded within a filter module structure. 

Recent developments in LM module design, including rotational, vibrational membrane devices, pulsed-flow fluid management for polarization control, use of low-cost refractory monoliths as membrane supports, and use of electric potentials to minimize macrosolute polarization and fouling, may permit practical and economic application of membrane processes to liquid and gaseous streams which today are untreatable by such methods. 

The UF membranes are protected from yarn fibers by a vibrating screen filter and 20 to 50 n cartridge filters. This makes possible the use of spiral wound modules which have a life of 24 to 30 months. The desizer waste effluent usually contains between 0.5 and 1.5% PVA. The UF concentrates this PVA up to 10% for direct use in the slasher. This final concentration is monitored and automatically controlled by an in-line refractometer. A small amount of desizer waste is purged to drain to prevent the buildup of low MW solutes. 

Bian et al (1999) reduced the concentration polarisation and fouling in NF by vibrations. Mallubhotla et al (1998) reduced the concentration polarisation by constructing helical modules from tubular membranes. 

The French mathematician Mathieu investigated this equation in 1868 to describe the vibrations of an elliptical membrane. Mathieu functions are applicable to a wide variety of physical phenomena, e.g problems involving waveguides, diffraction, amplitude distortion, and vibrations in a medium with modulated density. Hill was interested in the motion of planets and was thus engaged in differential equations with periodic integrals [1]. 

Human hearing arises from airborne waves alternating 50 to 20,000 times a second about the mean atmospheric pressure. These pressure variations induce vibrations of the tympanic membrane, movement of the middle-ear ossicles connected to it, and subsequent displacements of the fluids and tissues of the cochlea in the inner ear. Biomechanical processes in the cochlea analyze sounds to frequency-mapped vibrations along the basilar membrane, and approximately 3,500 inner hair cells modulate transmitter release and spike generation in 30,000 spiral ganghon cells whose proximal processes make up the auditory nerve. This neural activity enters the central auditory system and reflects sound patterns as temporal and spatial spike patterns. The nerve branches and synapses extensively in the cochlear nuclei, the first of the central auditory nuclei. Subsequent brainstem nuclei pass auditory information to the medial geniculate and auditory cortex (AC) of the thalamocortical system. 

Ahmed S, Rasul MG, Hasib MA, Watanabe Y. Performance of nano filtration membrane in a vibrating module (VSEP-NF) for arsenic removal. Desalination 2010 252 127-134. 

Feed-channel spacers — spiral-wound modules and some flat-sheet modules High shear — vibrating membrane High shear — rotating the membrane High shear — rotor above the membrane Dean vortices Pulsing the feed Baffles... 

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