EVALUATION OF THE DUAL DIGESTION SYSTEM .2. OPERATION AND PERFORMANCEOF THE PURE OXYGEN AEROBIC REACTOR

In a comprehensive study of the performance of a full-scale (45 m3) pu re oxygen autothermal thermophilic aerobic reactor of a sewage sludge dual digestion system, it was found that: Biological heat generation r ate was directly proportional to the biological oxygen consumption rat e at 13,1 MJ/kgO; respiration quotient (mol CO2 generated per mol O2 c onsumed) was 0,66; vent gas was saturated with water vapour even at th e high vent gas flow rates; COD and/or VS removal rates were poor para meters for quantifying the biological heat generation rate and control ling the reactor temperature. Increases in reactor temperature could b e completely and virtually instantaneously controlled by means of the oxygen supply rate (OSR) for as long as the reactor was oxygen limited . The rapidity of response and close correlation between the oxygen tr ansfer rate (OTR) and the biological heat generation rate make the OTR and the OSR pivotal parameters in the operation, control, design and simulation of oxygen limited autothermal thermophilic aerobic reactors in dual digestion.