Flux decline during ultrafiltration of kraft black liquor using different flow modules: a comparative study

Ultrafiltration of black liquor was studied in three different modules, nam ely, radial cross flow, rectangular cross flow and stirred cell over a wide range of operating conditions. Effects of different cut-off membranes on t he permeate flux and observed rejection were also studied in the stirred ce ll module. Effects of operating conditions, e.g. pressure difference, Reyno lds number and feed concentration on the permeate flux and observed rejecti on were also investigated. Such comparative study may be useful to select a suitable module, membrane and a set of optimum operating conditions to ach ieve a desired quantity and quality of permeate flux. A comparative analysi s of flux decline for different modules is also presented using a simple re sistance-in-series model. (C) 2000 Elsevier Science B.V. All rights reserve d.