|
|
|
|
LO-CROSS-FLO MICROFILTRATION Microfiltration (or cross-flow filtration as it is known in the cellar) is a relative newcomer to the wine industry. Traditionally wineries have been using D.E. filtration for all their bulk wine filtration needs. This has worked well in the past and continues to work fairly well but in most cases the wine needs to be filtered more than once in order to achieve final bottling quality. There is also the issue of the waste generated by the D.E. and the health risks associated with the use thereof. Microfiltration was introduced to the wine industry as a filtration technology designed to filter down to the 0.4 micron range on a single pass. This has many benefits to the winemaker since the wine now only requires a single filtration (in most cases) to achieve the quality required for bottling purposes. Up until now, the technology has proven itself on white wines, but the verdict is still out on the filtration of red wines. This is about to change! The microfiltration machine being marketed by VA Filtration (also offered as a mobile service in some places) is called a lo-cross-flo microfilter because it operates exactly like that. 90% of the time the system runs in the dead-end or semi-dead-end mode i.e. LITTLE OR NO CROSS-FLOW! We do not utilise the cross-flow action to keep the membrane clean but rather make use of a considerable increased surface area to compensate for any loss in flow rate. The membranes are the most important factor in the system. With increased surface area we are not only able to feed semi dead-end but have a lower flux rate per m2 with an immediate lower trans membrane pressure. All these factors equate to a less abrasive filtration system for wine. This benefit has the greatest effect on red wine since the wine is not re-circulated over and over again while undergoing filtration, as per the operation of most existing cross-flow filter systems. We have processed several thousands of liters through the system to date and the feedback from winemakers has been extremely positive - especially on red wine filtration. Currently we have machines operating in South Africa and Australia and soon the USA!
View of the Microfiltration machine - notice the mono-style pump! PRINCIPLES OF OUR MEMBRANE FILTRATIONMembrane cartridge filters are a combination of many individual capillary filtering membranes which are combined and then bonded into a single filtering cartridge. To understand the working of a capillary membrane filtering cartridge, we must first understand the single most important part of that element which is the individual capillary membrane. Capillary membranes are used primarily in a surface filtration mode. The primary mechanism of surface filtration is physical sieving, whereby it retains all particles larger than the hole or pore size at or near its surface or separating layer, which in our case is the inner bore wall. Our membranes are highly uniform, rigid, and chemically tolerant with regularly spaced uniform openings or holes. When a liquid is directed through our separating layer or skin (the inner bore of the capillary), those particles and micro-organisms larger than the hole or will be retained entirely on the surface or skin. Uniformity of pore size permits well defined limits or particle retention to be determined. While depth filters have their place in regards to high dirt handling, a reusable filtration product must have the ability to dislodge or easily break away debris or particles from the filtering or separating layer. Our filtering capillaries are designed specifically to trap particulates or debris onto the filtering surface (the inside bore of our capillaries), thus not allowing undesirable debris to accumulate into the matrix (inner) wall. We do not place the openings on our filtering membranes in such a way as to allow dirt or particulates to wind their way deep into the capillary wall or matrix. In summary, our process consists of passing an unfiltered solution through a porous wall with precise openings that trap those undesirable particulates or solids onto the separating surface for easy rejection or disposal. Key Benefits
|
|
Send mail to
rsvpbryan@msn.com
with questions or comments about this web site.
|
