Full plant scale experiments were made to determine the effect of heated aerobic digesters on digestion of waste water treatment plant sludge. Existing heated, floating cover equipped, anaerobic digesters, which had failed under excessive paper mill waste discharge, were converted to this purpose by addition of blower supplied air. Excessive odor production as temperatures increased prevented conclusion of the total program or any single phase. No practical method for control of temperature resultant from bacterial energy exerted in volatile reduction could be devised. The experiment was beneficial in determining the extent of practical application, and in establishing that thermophilic digestion temperature ranges could have produced significant volatile reduction. Determinations made also afford a measure of energy (heat) generated by aerobic bacteria in destruction of waste.