Filtration scaleup

N(w), is the amount of wash liquor used divided by the amount of liquor in the cake at the start of washing. Note that in practice results do not improve beyond about N(w)=3, fine solids wash better than coarse sohds, and that less than 10% fraction of original hquor remaining in the cake is seldom achieved. Understanding this general pattern will result in a scaleup with either a reslurry step and a second filtration, or the use of a filter like a Rosenmund that can reslurry the cake internally, and filter and wash again. 

Several leaf tests should be performed for repeatability. Data collected will permit scaleup to plant scale operations. Significant data will be pounds of dry cake per square foot per hour, gallons of filtrate per square foot per hour, filtrate clarity, wash ratios, (pounds of solids/gallon of wash), residual moistures, filtermedia selection, knife advance time, precoat thickness, solids penetration into precoat, and submergence level should also be evaluated. For the optimization equation, refer to Peters and Timmerhaus, and Tiller and Crump. 

The scaleup considerations of column chromatography for protein isolation has been described by Charm and Matteo.l l When several hundred liters of a protein feedstream must be treated, the resin may be suspended in the solution, removed after equilibration by filtration and loaded into a column from which the desired proteins may be eluted. Adsorption onto a previously packed column was not recommended by them since they feared suspended particles would clog the interstices of the column, causing reduced flow rates and increased pressure drops across the column. The reduced flow rate may lead to loss of enzyme activity because of the increased time the protein is adsorbed on the resin. 

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