Technical Bulletin No. 0080: The Microbial Oxidation of Pure Carbohydrate in the Presence of Calcium Lignosulfonate
Considerable speculation concerning the decomposition of lignins in surface waters is contained in the literature. This matter is of importance with respect to the discharge of chemical pulping liquors since lignia compounds form a major portion of the total organic load. Whether or not these compounds contribute to the oxygen demand should be determined. Reported in the attached Technical Bulletin are the results of experiments performed at the Council’s Bates College Project, under the direction of Dr. Walter A. Lawrance, regarding the rate of decomposition of calcium lingo-sulfonate as measured by oxygen consumption. The decomposition rate was measured for the lignin salt alone and in the presence of energy food in the form of various sugars. All tests indicated that over a period of fifteen days, little lignin salt decomposition takes place under the conditions of the experiment which resembled the surface water environment. The addition of sugars had little, if any, effect on the decomposition rate. In fact, the oxygen consumption was so low that it may have been due to a small quantity of impurities in the salt rather than to lignin itself. Hence, it was concluded from these tests that calcium ligno-sulfonate contributes little, if at all, to the oxygen demand of spent sulfite liquor.