By 3M Purification Inc (formerly CUNO)
Filter presses have long been used by breweries in cellar operations to clarify non-pasteurized or draft beer prior to final membrane filtering and packaging. This clarification process is essential to economical membrane filtration in that beer not prepared in this manner will more quickly plug the membrane filters, leading to higher processing costs. The filter press format has been popular for many years since it is generally reliable, and the filter sheets contained in them are relatively inexpensive, commodity items. A filter press is typically composed of a series of stainless steel frames that hold cellulose-based depth filter sheets or pads. Turbid beer is pumped through the filter sheets, which retain undissolved solids, yeast, most bacteria, hazes, and other turbidity causing components.
However, as breweries modernize and review their operations, with focus on improvements in efficiency and methods of sanitation when preparing beer for bottling, many upgrade the clarification process to include more cost effective, environmentally sealed cartridge filters in place of the filter press. Deficiencies in the filter press design are well known and include: leakage of beer, exposure of the filter media and beer to contaminants in the environment, oxygen pickup, high labor and maintenance costs, and high capital costs for the equipment.