Foul Condensate Stripping

In recent years the in-plant treatment of waste condensate has become an accepted method for the removal of odorous gases and BOD (Biological Oxygen Demand). This treatment has been necessitated for environmental reasons as the pollution control regulations have become increasingly stringent. A. H. Lundberg Inc. has developed steam stripping systems designed for the removal of malodorous gases or both the gases and BOD.

The condensate streams of concern include the liquor condensates of the multiple effect evaporator, the overflow of the blow heat accumulator and the underflow from the turpentine decanter. Each of these streams are contaminated by organic sulfides (TRS- Total Reduced Sulfur) and volatile organic compounds that contribute to the BOD load.

The TRS gases are a result of the kraft pulping reactions. Among the TRS compounds are hydrogen sulfide, methyl mercaptan, dimethyl sulfide and dimethyl disulfide. These are noxious gases with a very low threshold of odor detectability, as shown in Table I. Thus, before any of these streams can be used in the mill or discharged to waste water treatment, the TRS compounds must be removed at a high efficiency.

A.H. Lundberg, Inc., 2803 Hewitt Ave., PO. Box 1506, Everett, WA 98206. Tel: 425-258-4617; Fax: 425-259-1037.