RVF - Rotating Vibrating Filtration System
RVF (rotating-vibrating filtration) is designed for filtration of highly concentrated liquids characterized with high fouling and/or clogging characteristics. It uses disc-shaped flat sheet membranes in the vicinity of the rotating bodies. These rotating bodies as well as the pulsating blows generate highly dynamic vortex movements of filtered liquid being in contact with the membrane surface resulting in high values of shear rates thus preventing any particles or molecules to accumulate on the surface of the membrane or to enter inside the pores. Flow rate through the pores remains stable and being at a high level even with highly concentrated liquids to be filtered.
The innovation lies in the possibility to extend the use of membrane filtration with more and more concentrated and viscous liquids with highly fouling characteristics (silt density index, SDI) such as liquid industrial wastes, fermentation broth (rough beer), natural extracts, etc.
Apparatus (Fig. 1) contains a number of the filtration cells stacked around the shaft, each of them is composed of the following parts:
- porous backing plate draining the permeate to the periphery of the cell;
- membranes arranged onto the two faces of that porous backing plate (Fig. 2);
- rotating bodies arranged in the immediate vicinity of the des membranes and driven to the rotation by that shaft (Fig. 3).
The liquid to be treated is introduced into the apparatus and driven to the rotation by the said bodies (Fig. 3 - rose color arrows). The resultant movement of that liquid is the combination of the tangential component as well as vortex and pulsating ones. Under the effect of a pressure difference said liquid is separated by the membrane on the permeate (filtrated part: Fig. 3 - blue color arrows ) and the retentate (concentrated part: Fig. 3 - dark red color arrows). Membranes and backing plates remain stationnary.
Main Parameters of the Liquids that can be Treated With RVF
Viscosity up to 800 cP
Very clogging liquids can be treated: high values of TSS, DS, COD, concentration of high molecular organic matters
This technology requires only very slight prefiltration upstream NF and RO: SDI index of the waste water to be treated can be very high (> 20 or even non-measurable ones)
Area of the developed RVF filtration plants
Model series of the RVF filtration plants:
Plants operating at low pressure: MF & UF processes;
Plants operating at high pressure: NF & RO processes;
- Application range of the RVF filtration plants:
Plnts for food industry: MF & UF processes;
Plnts for pharmaceutical industry: MF & UF processes;
Plnts for environmental protection industry (industrial WWTPs): NF & RO processes;
Maximum pressure reached to date is 55 bar
Average linear velocity of the concentrate in the vicinity of membrane's surface: 6-15 m/s;
Power consumption of the plant used for:
MF & UF processes: 4-8 kWh/m3
NF & RO processes: 20-40 kWh/m3
High recoveries can be reached
Permeate flow rate is 1.5-8 times higher compared to the classical cross-flow filtration
Very low pressure drop in the filter and concequently very low circulation pump's power required
Can be charged with organic membranes, stainless steel or metal-ceramic ones.
Long cycles of operation between cleanings result in:
increased production capacity of the plant
economy of the reagents and the energy for CIPs
preservation the environment by lowering the volume of waste waters produced
The rejection and the permeability of the membrane stays stable due to low fouling
Ability of the plant to be adapted to the client's verying requirements by means of:
Adding or removing the membrane disks
Changing the type of the used membranes
Why RVF can be interesting for you?
Because the membrane fouling generates a lot of problems.
Fouling, clogging and concentration polarization induce flow rate reduction down to unproductive threshold. Filtration must be stopped to proceed the cleaning procedure of the membranes.
RVF offers an excellent alternative to classical technologies: press or candle filters with temporary filtration media such as kieselguhr, classical tubular membrane filters, combination of several filtration technologies (multi-stage treatment), etc.
Advantages lay in the possibility to filter with membranes the liquids that are usually separated or concentrated with others expensive technologies. RVF reveals quasi-stable and high flow rate, low consumption of cleaning agents, etc.
The result of the fouling for client is:
- Production loss
- Chemicals and energy consumption
- Membranes’ accelerated aging
- Waste wash water generation
- Alteration of the membrane cut-off characteristics
RVF technology gives a major advantage: RVF-filter show very slow fouling. Continuous dynamic unstationary effect o the fluid onto the membrane makes RVF to be different and innovative technology.
Membrane performances remain stable permanently:
- With a very rough pretreatment of the fluid to treat
- Without frequent periodic membrane cleaning
Mean flow rate is stable and higher for a similar liquid with the same membrane compared to classical cross-flow filtration technologies. Filtration operating conditions and performances of the membrane are stable both for flow rate and rejection
- Membrane is cleaned permanently by the liquid being in movement
- Fouling and concentration polarization are reduced
- Permeate flux remains at a high level and nearly constant
- Long periods of filtration between cleanings
- Reduced frequency of the cleaning in place (CIP)
- Moderate energy consumption
- Moderate cost of the equipment
- Universal technology: MF, UF, NF & RO
- Possibility to treat viscous and heavily charged liquids
- Maximum pressure of functioning is 55 bar
- Medium velocity of retentate is 10 m/s
- For NF or RO very light pretreatment only is necessary
- Can be used in the food, pharma and environment applications
Filtration of the industrial waste waters
Chemical industry often generate waste waters issuing from the washing reactors and pipes.
The following fields are concerned:
- Production of paints, primers blends, polymers for surface treatment
- Production of washing agents, detergents, soaps