Thermodynamic modelling is needed to describe the effect of high temperature on microbial nitrogen removal processes

Abstract

Existing models of nitrogen removal and related microbial reactions in conventional wastewater treatment plants are capable of describing most of the relevant behaviour of these plants. These models may however fall short on describing the effects of temperature on the microbial activity including the inhibition of nitrite oxidation. In this work a detailed model is presented incorporating the most and also some of the less commonly observed microbial nitrogen reaction pathways. The model calculates thermodynamic variables dynamically based on the dynamic concentrations. This allows for a detailed dynamic analysis of the thermodynamic feasibility of all reactions and of the effects of temperature. The results indicate that the well-known inhibition of nitrite oxidation at high temperature is caused by thermodynamic limitations.