rotary drum vacuum filter (or RDV filter), specialized form of earth filtration designed to cope with very ‘dirty’ liquids—those which contain a high concentration of solids or particles that would rapidly block other filters. Such liquids arise during the winemaking process when hazy juice or wine is allowed to settle through the action of gravity; the resultant lees, although still liquid, are frequently very thick and require mechanical sieving to separate the valuable liquid from the solid particles suspended in it.
