A simple strategy for controlling the nitrate concentration in an activated sludge process using external carbon flow rate

摘要

Biological nitrogen removal in an activated sludge process is obtained by two biological processes; nitrification and denitrification.Denitrifying bacteria need an anoxic environment and access to an organic energy source in order to convert itrate to nitrous oxide.Often an external carbon source has to be added in order to achieve a high denitriflcation rate(giving a low effiuent nitrogen discharge).Both for process efficiency and economy it is of interest to control the flow rate of external carbon.In this paper,a model based feedback-feedforward controller with measurements of teh states is presented for controlling the nitrate concentration using the external carbon flow rate.The main approach is to use exact linearization on a simplified IAWQ Activated Sludge Model no 1.By using some further simplifications,some measurements can be avoided and other easily estimated from the output leading to a more feasible output feedforward controller which still has a similar performance as the feedforward-feedback linearizing controller.Simulation results using the full IAWQ Activated Sludge Model no 1 is used to illustrate the ocntrollers performances.