Air pollution control in kraft pulp mills

A patented gas scrubbing process, whereby the emissions of malodorous reduced sulphur compounds are effectively and economically reduced, is described. Stack gases are scrubbed with an alkaline suspension of activated carbon. Reduced sulphur compounds as well as sulphur oxides are converted to sodium salts which are subsequently recovered and utilized for pulping. The process also reduces particulate emissions. It does not produce subsequent waste disposal problems and has little or, in some cases, zero net cost, on account of the simultaneous recovery of heat and chemicals. Furthermore, the paper also reviews some innovations made in gas chromatography techniques, for the measurement of trace quantities of sulphur compounds present in kraft mill emissions.