EFFECT OF RAPID TEMPERATURE-CHANGE AND HRT ON ANAEROBIC ACIDOGENESIS

The effects of the rapid change in temperature and HRT on the characte ristics of substrate degradation and bacterial population levels in an aerobic acidogenesis a,ere investigated by using the laboratory scale anaerobic reactor. The degradation efficiency of substrate in acidogen esis was significantly affected by the rapid drop in temperature parti cularly at short hydraulic retention time and low temperature. The n-b utyrate concentration was increased or decreased for the same change i n temperature when the HRT conditions were different from each other. The numbers of acidogens, homo-acetogens and H-2-utilizing methanogens were not affected in the first 3 days after temperature was rapidly d ropped at all the temperature conditions. At 15 degrees C, the complet e washout of acetate-utilizing methanogens was observed. The bacterial forms varied according to the changes in the hydraulic retention time and temperature. (C) 1997 IAWQ. Published by Elsevier Science Ltd.