Recovery and recycling of suspended matter and clarified liquor - from effluent arising in prodn of paper- or mechanical wood pulp

摘要

Recovery of suspended matter from and purification of the effluent from the mfr. of paper- or mechanical wood pulp by (i) passing the effluent contg. the suspended material alternately into at least two and pref. three sedimentation tanks and as soon as such a tank is filled (ii) interrupting the feed of effluent thereto, (iii) allowing the suspended material to settle for 20-50 min. and pref. for 25-40 mins., (iv) drawing off the supernatant liquor and passing it to a filtration bed planted with growing reeds, (v) allowing the effluent flowing from the filtration bed to flow through the root space of an elimination bed of growing rushes, (vi) recycling the resultant to the paper- or mechanical wood pulp prodn process and recycling the settled suspended material from the sedimentation tanks before new effluent is introduced therein. Allows at least partial recovery of the suspended material, i.e. fine fibrous particles in the effluent which might otherwise be lost in the effluent purification process, as well as permitting the recycling of a major part of the effluent.