A Technology Feature Article
Technology: Rotary Drum Vacuum Filtration
Type: Filtration & Membrane Technologies
Rotary Drum Vacuum (RDV) filtration is an ideal technology for the efficient recovery of juice or wine from a number of winemaking products such as freshly pressed juice, settled gross lees, must and wine lees, and enzyme treated fruit juices.
The RDV filtration process recovers juice and wine from lees that would otherwise be discarded. As much as 80 percent of juice from lees that was once dumped down the drain can now be kept – all adding to yield per tonne of grapes harvested.
RDV is one of the oldest concepts in modern filtration, patented in 1872. It is ideally suited to the filtration of slurries and liquids with high solids content. The filter’s operation is continuous and automatic so operating costs are relatively low.
The machine consists of a large drum covered by a fine mesh or cloth. This is suspended by an axle over a tub. When setting up, the tub is filled with a mixture of water and diatomateous earth (DE) or more commonly, perlite as the filter medium. As the drum rotates about the axle, a vacuum applied to the interior of the drum draws the filter medium onto the surface of the drum to form a cake.
Vintech Pacific use exclusively expanded perlite as the filter medium, rather than diatomateous earth. Filter grade DE is a crystalline silicate, which can cut the throat and lungs if inhaled. Perlite meanwhile, is an amorphous (un-crystallized) silicate, containing less than one tenth of one percent (.001) crystalline and so is much safer to handle. DE is classified as a carcinogen and must be disposed of as hazardous waste. According to the FDA, perlite does not pose any health risks and does not have any stringent disposal criteria.
With the cake in place, the tub is drained of remaining filter medium and them filled with the liquid to be filtered. This time, as the drum rotates about the axle, the vacuum applied to the interior of the drum draws the suspension onto the surface of the filter cake. The liquid filtrate passes through the cake and the suspended solids remain on the surface of the cake.
The clean filtrate can now be passed to storage. In the case of juice recovered from lees for example, the filtrate can be added back to the settled juice to undergo fermentation.
As the drum continues to rotate, now with the filtered solids on the exterior surface, a blade removes the solids and a thin layer of the filter medium cake, which is collected as waste. The blade is automatically advanced to continuously remove this thin layer, along with the solids as the diameter of the cake reduces through the process.
To discuss how Vintech Pacific and our Rotary Drum Filtration technology can bring efficiencies to your winemaking program, please contact your nearest Vintech Pacific regional office.
|Head Office, Gisborne
Phone: 06 863 0028
Mobile: 021 783 236
|Auckland & Napier
North Island Manager
Phone: 06 863 0028
Mobile: 021 410 498
|Blenheim & Cromwell
South Island Manager
Phone: 03 570 2996
Mobile: 021 779 180