Bioprocessing refers to the production of biologically active therapeutic and diagnostic proteins that are expressed by mammalian or bacterial cells. A series of unit operations isolates and purifies the products of fermentation. A schematic drawing showing the various unit operations involved in a typical bioprocessing activity is given in Figure 4.28 . In most cell […]
Soybean is an important source of protein, and the process to recover the protein and fat requires the removal of undesirable compounds. Traditional removal methods include extraction, heat treatment and centrifugation to separate the protein and fat from these compounds. Hollow fibre ultrafiltration modules are used to recover full fat soy protein concentrates and soy […]
Reverse osmosis is used to considerable advantage in the food and dairy industry, the main reason being the cost reduction compared with evaporation consequent upon the elimination of this process. Some advantages and disadvantages of reverse osmosis in food processing are given in Table 4.5 . Applications of reverse osmosis in the dairy industry include […]
The first reference to the use of filters for clarifying water, milk and wine can be found in Egyptian times. From wool and cloth, paper and charcoal to sea sand and sacking, many materials were used and found to be inadequate. It was not until the latter part of the nineteenth century, in Germany, that […]
The photoresist solution is a particularly difficult fluid to filter, but this must be done to exacting standards, in order to ensure transfer of patterns onto thin films. Not only must the photoresist be filtered, but so also must the solvents used in developing the resist. Particulate contaminants in photoresist are either undissolved polymers or […]
The use of gases in integrated circuit fabrication is increasing, particularly with VLSI technology. This technology is demanding more and more dry processing in order to achieve sub-micrometre geometries. These dry processes are, for the most part, based on the use of gases as reactants. Thus, there is an increasing dependence upon clean, dry, particle-free […]
Filters for applications in etching processes are required to be capable of withstanding a broad range of aggressive chemicals, from strong acids to strong bases or strong solvents. The filters must exhibit low levels of extractables under the operating conditions of this broad range of chemicals, and must not be susceptible to releasing fibres. The […]
The chemicals utilized for etching are aggressive acids, such as hydrofluoric, nitric and phosphoric. Other chemicals are used to clean the surface of the wafer, preparing it for the next stage in the fabrication process. All of these chemicals are potential sources of particulate contamination. With respect to etchants there are two major sources for […]
The critical applications in the electronics industry are the production of ultra-pure water for the washing of semi-conductor material (silicon chips), and the cleaning of the chemical fluids (liquid and gaseous) used in their manufacture. The object of an ultra-pure water plant for semi-conductor manufacture is to produce water as close to the theoretical purity […]
An interesting extension of the range of vacuum filters is the capillary disc filter ( Figure 4.26 ). This is a continuously operating, capillary action, ceramic dewatering filter, which eliminates the need for separate filter cloths. The filter medium is a disc, formed from two circles of sintered alumina, joined at their circumferences. The filter […]
