Studies on Aerobic Digestion of Sludge in Intermittently Aerated Activated Sludge Plants in Connection with Low Temperatures in the Activated Sludge Tanks

In the past, activated sludge plants with intermittent aeration and simultaneous aerobic digestion were designed like activated sludge plants with continuous aeration, i.e. pauses in aeration were not considered. Scale bench tests on SBR-plants and a temperature about 20 degrees celsius in the activated sludge tanks were made. The result showed, that even during the idle period the microorganisms are supplied to some extent with oxygen by the oxygen present as nitrate in the settling sludge, at least some of the idle period could be included as reaction time as well. Now we want to make further scale bench tests on SBR-plants with low temperatures in the activated sludge tanks. The result of these tests should show the influence of intermittent aeration in connection with low temperatures on aerobic digestion of sludge.