Technical Bulletin No. 0193: COD and BOD Relationships of Raw and Biologically Treated Kraft Mill Effluents

The attached National Council Technical Bulletin No. 193 reports on a study made at the Johns Hopkins Research Center with the assistance of a number of kraft pulp mills. William L. Carpenter conducted this investigation which dealt with the feasibility of estimating the BOD of raw and treated kraft pulp mill effluents by applying a factor to the chemical oxygen demand value. If such could be achieved, automated monitoring could be applied to effluents. Unfortunately, no reasonably constant relationship was found to exist between COD and BOD values of either the .untreated or treated waste. This is because the percentage of materials refractory to biological oxidation, such as lignins, varies almost continuously in the mill effluents. However, establishment of this fact and the lack of correlation between the two values justify the effort put forward since it will mitigate against unsound data interpretation in the future.