STOAT and the oxygen requirements of an activated sludge plant

The various activated sludge models within STOAT, a whole works package, were used to predict the oxygen requirements of a hypothetical activated sludge plant. The predictions which were obtained were then compared with the values calculated from standard equations. The results showed that there were very definite differences both between the predictions made by the models and between the model predictions and those produced using standard equations. The results also showed that, for carbonaceous oxidation, the GOD-based model in STOAT (IAWQ model) was applicable to a wider range of process conditions than the BOD-based model (ASAL model). The IAWQ model was also found to be a more useful tool in optimising a nitrogen removal system.