Abstract: The invention relates to a process for the separation of biotechnologically produced valuable materials form a cell suspension by crossflow microfiltration to obtain an high specific permeate flux while retention stays near 0% for long periods. To enable crossflow microfiltration to be carried out on an industrial scale in biotechnology in the separation of biotechnologically produced extracellular valuable materials from a cell suspension, particularly in the separation of alkaline protease for recovering enzyme, under economically acceptacle conditions, alkaline protease of relatively high molecular weight, more especially enzyme >20,000 daltons, is separated from a fermenter solution using polysulfone tubes having micropore diameters of from 0.3 to 0.5 .mu.

Abstract: An improved reactor (and process using the same) comprising multistage stirrer elements and baffles, which has particular dimensional ratios between the reactor diameter, the width and spacing of the stirrer elements, and the baffles. The reactor is particularly adapted for the production of polysaccharide ethers, especially cellulose ethers.

Abstract: A process for the production of carboxyalkyl celluloses having an average degree of substitution of at least 1.0. The process comprises up to 3 stages, but without any intermediate purification. The preferred suspension medium is isopropanol. In each stage of the process, the carboxyalkylating agent is used in quantities of less than 2.5 moles per mole of anhydroglucose unit and the alkylating agent in quantities of less than 5 moles per mole of anhydroglucose unit. The total water content of the system throughout the reaction as a whole must not exceed 450% by weight, based on the quantity by weight of cellulose used. Water contents of from 80 to 250% by weight are preferred.