Evaluation of pH inhibition effect on activated sludge by the pseudo toxicconcentration (C-PT) concept model

It is generally accepted that the inhibition effect of pH on activated slud ge follows the noncompetitive inhibition kinetics. But the non-competitive inhibition kinetic equation cannot be directly applied to pH inhibition, du e to the difficulty in quantification of pH as a term of inhibitor concentr ation. So, many empirical equations were developed especially for acidic co ndition to describe pH inhibition effect. In this research, the pseudo toxi c concentration (CPT) concept model to quantify pH inhibition effect on act ivated sludge was proposed and compared with other existed models. Predicti on of performance, presented by Prediction Accuracy and Prediction Accuracy Index, showed that the C-PT concept model can explain the reduction of the maximum specific growth rate (mu (max)) more accurately than any other mod els do at a wide range of pH. The C-PT concept model was applicable not onl y to activated sludge but also to specific microorganism groups, such as ni trifier, less acidophilic species and nitrifying biofilm.