Degradation of lignin by combined chemical and biological treatment

Abstract

Abstract It has been demonstrated that ozone dosages of 0.06 lb and 0.78 lb per pound of lignin can reduce the optical density (in the visible range) of the latter by 82% and 92%, respectively. The reduction in color is accompanied by a shift in the molecular weight distribution of lignin from a broad peak of between 20,000 and 70,000 to lower molecular weight, species including substantial amounts possessing a molecular weight of 1000 or less. The cost of decolorizing a typical kraft paper bleach effluent is estimated to be under 50¢/1000 gal which compares favorably with competitive decolorizing processes. Lignin ozonation results in the production of a series of decolorized products which can serve as the sole source of carbon for a variety of microorganisms. Feasibility studies indicated that at least 40% of the ozonated material can be transferred into microbial biomass (protein) as well as other products of commercial interest such as fumaric acid and penicillin.