The object of this research investigation was to establish whether or not a correlation exists between bottle B.O.D. and CO₂ liberated from a highly aerobic sewage-sludge mixture. The first part of the project consisted of reducing the number of variables in the operation to a minimum. To this end, considerable time and effort was spent finding the relationship existing between the condition of the sludge and its oxidizing potentiality. A definite strong statistical correlation was found to exist between the CO₂ liberated and the suspended solids or organic matter in the sludge. The apparatus functioned very well as could be readily seen from the consistent results obtained with the four units operating simultaneously. / Master of Science