Enzymatic Improvement of a Membrane Filtration Process for the Paper Industry, 2000 Environmental Conference Proceedings

- M. Nissen, H. Manner, R. Lantto, J. Buchert -- One method to overcome problems with system closure in pulp and paper industry is membrane filtration of circulation waters. In membrane filtration the clean fraction called permeate is reused in process but the dirty fraction called concentrate is usually induced to the outlet as waste. To reduce the amount of waste the concentrate should be processed for example by burning. The problem associated with membrane concentrates is the low amount of dry matter which impairs further filtration or compression enhancing combustion. Due to the presence of wood derived materials in the concentrates, enzymes are potential tools for the modification of the properties of the concentrates into a more favorable form. In this study the suitability of enzymes hydrolyzing pectin, glucomannan and xylan was compared for the treatment of various concentrates. The improvement of filterability after the enzymatic treatments was evaluated as a function of the secondary filtration. The purpose of the secondary filtration was to remove water from the concentrate before combustion. The filterability of concentrates improved significantly by mannanase and cellulase enzyme treatments suggesting that the main carbohydrates in the concentrates studied were glucomannan and glucan.