SpinTek - Model ST-II - Rotary Membrane System
A next generation rotary membrane system is now available from SpinTek Systems for filtration and fractionation of high fouling and viscous feed solutions. The patented rotary membrane device provides a high shear force to prevent membrane fouling with a wide variety of feed solutions containing moderate to high solids levels. The ST-II is available in small laboratory sized units up to full production sized models for the food, beverage, and chemical industries. Successful operation has been performed in 90%+ recovery of protein from cheese whey, submicron filtration of lube oil, non-settleable solids concentration above 6,400 cP and fine chemical dewatering to above 40% solids. Systems are available with flow rates from 1 lph to over 50 gpm with operating pressure to 150 psig. The ST-II can use polymeric membranes, ceramic membranes and metallic membranes in various pore sizes and can also be configured to utilize any commercially available flat sheet membrane.
SpinTek has developed a new generation high speed rotating membrane filtration system for laboratory and industrial filtration applications. The new SpinTek ST-II utilizes membrane disks that are rotated at variable speeds up to 20m/s to achieve an antifouling force enabling membranes to solve problems not possible before with conventional membrane systems. The new ST-II offers high and stable membrane flux allowing long term operation between cleaning, the ability to concentrate material up to 6,400 cP, and also to very effectively fractionate closely sized material. The ST-II is capable of this operation due to its unique design of spinning the membrane configured disks near a stationary element. This concept provides a very high relative velocity and shear between the membrane and the feed water effectively minimizing membrane fouling. This translates to high filtrate flow rates. The energy to control fouling is transferred directly to the membrane surface where it is most effective. The ST-II does not require large and expensive recirculation pumps to attempt to minimize fouling as with conventional static membrane systems. The ST-II is capable of effectively controlling the boundary layer which causes fouling and reduction of permeation flow--power is transferred directly to the membrane surface for highest efficiency. The ST-II has a unique rotating membrane disk design that eliminates the need for artificial turbulent promoters that can plug with solids and lower system performance. The ST-II can be operated as a microfilter, ultrafilter or nanofilter.
Two major effects are created by the dynamic spinning action of the new SpinTek ST-II system. The high shear allows for concentration and dewatering of solids to in some cases above 40%. It also keeps the membrane surface clean so that permeation of material below the cut off size of the membrane can occur. This is especially useful in such applications as bacterial filtration of food or chemical solutions, and protein separation from fermentation broths. Specific examples of ST-II successes are vanilla extract bacterial filtration without color loss, latex recovery up to 50%, hydrated aluminum concentration to 40%, yeast concentration above 35%, biodigester sludge concentration and blood plasma fractionation.
Laboratory sized pilot units are available with 0.5 ft2 of membrane area and larger pilots up to 25 square feet are also available. Both types of field test units can be configured with a wide range of polymeric membranes including TFC, PVDF, polysulfone and others plus a selected supply of ceramic membranes. Most membranes are available in pore sizes ranging from 200 NMWC up to 3 microns. Virtually any type of custom membrane developed by materials researchers can also be configured into the ST-II laboratory pilot. Field test data for many applications are available from SpinTek. Pilot units are available in both standard and explosion proof ratings.
Small lab size units are available as well as production sized units of with up to 150 square feet of membrane surface. The systems are capable of processing small volumes up to 50 gpm of permeate flow rate. All stainless steel construction, explosion proof and sanitary versions are available. Piping, instrumentation and controls can be configured to meet any plant specifications and requirements.
The rotation of the membranes allows for the energy to be applied directly to the membrane surface where it is needed to reduce fouling and the boundary layer. Efficiency is not lost by utilizing large, high pressure pumps to recirculate mass amounts of feed solution through the system to reduce fouling. It is typical for traditional cross flow membrane filters to recirculate over 98% of the feed stream, whereby the SpinTek ST-II requires less than 50% recirculation which is used for mixing. The ST-II, due to the high rotor speed, is capable of controlling the boundary layer to effectively cause fractionation. Membrane filtration is now possible for fractionation of similarly sized particles. An example is defatting of cheese whey. Conventional static membrane systems build up a layer of solids and fat on the membrane surface which impedes the passage of pure protein through the membrane by up to 65%. The ST-II prevents this material build up on the membrane and allows passage of over 95% of the protein at the same time withholding 90%+ of the fat. Membrane filtration systems have been plagued in the past with severe membrane fouling, concentration limitations, low fluxes and device plugging. The ST-II can operate without prefilters.
- Polymeric membranes--hydrophilic and hydrophobic, low protein binding, solvent resistive
- Ceramic membranes
- Metallic membranes