Start-up performance and process kinetics of a UASB-Anammox reactor at low substrate concentration

In this study, the start-up performance and process kinetics of a UASB-Anammox reactor with nitritation sludge at low substrate concentration were evaluated. The results demonstrated that the UASB-Anammox reactor was successfully started by inoculating with a mixture of nitritation sludge and anaerobic ammonium oxidation granular sludge. After 120 days of operation, good nitrogen removal was obtained by anaerobic ammonia oxidation(Anammox). During start-up and operation of the system, TN load removal exhibited an "S-shape" curve. An analysis using microbial growth kinetics models showed that the Logistic Model, the Modified Logistic Model, the Modified Gompertz Model and the Modified Boltzmann Model could all describe the experimental data of TN removal. The process kinetics analysis also showed that nitrogen removal by the UASB-Anammox reactor operating under steady-state conditions can be simulated using the Grau Second-Order Model and the Modified Stover-Kincannon Model. Parameters obtained from the model analysis facilitate the prediction of nitrogen removal performance, operation management and control of similar reactors.