Decolouring waste water from cellulose factory - spent calcium hydroxide from filters used for green lye

摘要

A method for decolouring waste water from a cellulose factory esp. waste water from the bleaching station in a sulphate cellulose factory by means of filtering the waste water through a layer of Ca(OH)2 characterised by the use of the spent Ca(OH)2 from the filtration of the waste water which still contains appreciable quantities of Ca(OH)2 unreacted with the coloured constituents of the waste water, for rendering the green lye caustic.