Concentration of ferric hydroxide suspensions in saline medium by dynamic cross-flow filtration

Bouzerar, Roger; Jaffrin, Michel Y.; Lefèvre, Amélie; Paullier, Patrick

doi:10.1016/s0376-7388(99)00226-4

Cited by 20 publications

(18 citation statements)

References 14 publications

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“…Some experimental data presented in [13,14,25] are similar to our own results. Ould-Dris et al [14] investigated the stability of cakes formed by calcium carbonate particles on MF organic membranes by imposing cyclic variations of transmembrane pressure, crossflow velocity and particles concentration.…”

Section: Resultssupporting

confidence: 87%

“…In a complementary study, OuldDris et al [13] pointed out that at 1 bar the permeate flux of a CaCO 3 suspension 100 g/l decayed rapidly with time at a velocity of 0.1 m/s, whereas it remained nearly constant and equal to the pure water permeate flux for crossflow velocities higher than 0.8 m/s. Bouzerar et al [25] found out that the permeate flux of a suspension of ferric hydroxide 9 g/l through a flat MF zirconium oxide membrane mounted in a dynamic crossflow device (rotating disk) raised linearly with pressure with a slope equal to the membrane hydraulic permeability, confirming the absence of a deposited layer on the membrane, although the system operated in the laminar boundary layer regime. Besides, the permeate flux did not decay with time nor presented hysteresis in cyclic variations of rotation speed.…”

Section: Resultsmentioning

confidence: 98%

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Crossflow microfiltration of marble processing wastewaters

Afonso¹,

Alves²,

Mohsen

2002

Desalination

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The wastewaters generated during the marble processing (cutting and grinding operations), the average flow rates of which are ca. 15 m 3 /h for a plant producing 45 m 2 of polished marble/h, contain a high load of particulate matter. Furthermore, crushed stone operations sometimes use flotation agents, such as organic amines, fatty acids, and pine oils, in order to remove impurities from the marble. Therefore, the marble processing wastewaters should not be disposed directly into the environment without a suitable treatment in order to prevent negative impacts and comply with the national legislations currently in force. On the other hand, bearing in mind the severe water shortage in Mediterranean countries, which are intensive producers of carbonaceous rock and stone, it would be of utmost importance to recover and reuse the processing wastewaters generated in these plants. In this work, the treatment of marble processing wastewaters by microfiltration (MF) was investigated. Wastewaters from a marble processing plant located in Pero Pinheiro, Portugal, were characterised in terms of pH, conductivity, total solids (TS), and total suspended solids (TSS). A Micro Carbosep 60 module equipped with a mono-tubular mineral MF membrane, Carbosep M45 (nominal pore size = 0.45 µm, ID = 6 mm, L = 0.60 m), was tested at ambient temperature, natural effluent pH, a broad range of transmembrane pressures and crossflow velocities, and up to a 9-fold concentration. MF eliminated the suspended matter from marble wastewaters, allowing the treated water to be recycled into the process, whereas the concentrated stream (rich in particulate matter) can be used elsewhere, e.g. in the ceramic industry. The results from this work clearly show that MF is an efficient and ecologically suited environmental technology for decontamination and recycling of the wastewaters generated by marble processing plants, besides the environmental pollution abatement involved.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 98%

Crossflow microfiltration of marble processing wastewaters

Afonso¹,

Alves²,

Mohsen

2002

Desalination

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“…The flow field induced by the rotation of a flat disk parallel to a flat plate has been described previously by various authors (Bouzerar et al, 2000a(Bouzerar et al, , 2000bWilson and Schryer, 1978). Since in our case the axial gap between the membrane and the disk was relatively large (10 mm) the flow was of boundary layer type and turbulent except at low speeds and in the central part.…”

Section: Pressure and Shear Stress Distribution On The Membranesupporting

confidence: 57%

“…The filtration unit used for separating the exopolymer from the cells in the fermentation broth was a rotating disk module designed and built in our laboratory that has been described by Bouzerar et al (2000a). It consisted in a 15.4-cm inner diameter short cylindrical housing machined from polyamide PA6, inside which a 15-cm diameter aluminum disk rotates at speeds up to 3000 rpm around an horizontal hollow shaft which serves to evacuate the retentate (Fig.…”

Section: Filtration Unitmentioning

confidence: 99%

Microfiltration and ultrafiltration of polysaccharides produced by fermentation using a rotating disk dynamic filtration system

Brou

Jaffrin

Ding

et al. 2003

Biotech & Bioengineering

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The recovery of exopolysaccharides (EPS) produced by Sinorhizobium meliloti bacteria by dynamic microfiltration was investigated using a rotating disk device designed in our laboratory, equipped with a 0.2 microm nylon membrane. This system differs from commercially available systems by the presence of vanes on the disk which produce a very important increase in permeate flux while yielding excellent EPS transmission. For polymers produced under standard fermentation conditions (70 h at 30 degrees C), the mass flux rose to 650 g h(-1) m(-2) using a disk equipped with 2 mm vanes rotating at 2000 rpm against 380 g h(-1) m(-2) with a smooth disk at the same speed. The maximum flux observed was 1560 g h(-1) m(-2) with a 6-mm vanes disk rotating at 3000 rpm and a 36 degrees C broth. An interesting finding was that the permeate flux J(f) for various disks can be correlated by the same function of the mean shear stress at the membrane tau(wm) according to J(f) = 4.6 tau(wm) (0.717) for a 30 degrees C broth, showing that the effect of vanes is merely to increase the shear stress by raising the fluid core velocity between the membrane and the disk. With 6-mm vanes the core angular velocity was found to be 84% of disk velocity vs. 45% for a smooth disk. When the fermentation temperature was increased to 36 degrees C to produce a lower molecular weight polymer, the permeate flux rose by about 250%, much more than what could be expected from the reduction in permeate viscosity and followed the same power law with membrane shear stress as for 30 degrees C. The same device was equipped with a PES 50 kDa membrane to concentrate EPS by ultrafiltration. Permeate fluxes were of the order of 160 L h(-1) m(-2) at 2000 rpm and 30 degrees C with nearly complete EPS rejection. Finally, the net electrical power consumed by the disk was measured by subtracting the power consumed without fluid from the power during filtration at the same speed. This power increases with speed and with the presence of vanes, but since the gain provided by the vanes is very high, the specific energy per m(3) of permeate is minimal with the highest vanes tested (6 mm) and maximal for smooth disks.

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“…This device proved itself in our laboratory to be very effective for filtering various suspensions, such as ferric hydroxide suspensions in saline Ž . medium Bouzerar et al, 2000 and fermentation broths Ž . Harscoat et al, 1999 .…”

Section: Discussionmentioning

confidence: 99%