In this paper a model predictive controller (MPC) for ammonia nitrogen is presented and evaluated in a real activated sludge process. A reduced nonlinear mathematical model based on mass balances is used to model the ammonia nitrogen in the activated sludge plant. The results of the ammonia MPC were compared with the results of the ammonia feedforward-PI and ammonia PI controllers from our previous study. The ammonia MPC and ammonia feedforward-PI controller give better results in terms of ammonia removal and aeration energy consumption than the ammonia PI controller because of the measurable disturbances used. On the other hand, with the ammonia MPC slightly poorer results than with the ammonia feedforward-PI controller are obtained. Further improvements to the MPC could be possible with an improved accuracy of the nonlinear reduced model of the ammonia nitrogen, more sophisticated control criteria used inside the controller and the extension of the problem from univariable ammonia to multivariable ammonia and nitrate nitrogen control.
COBISS.SI-ID: 25016103
In this paper modelling and simulation based on ADM1 model are used to find the possibilities to improve the operation of the sludge treatment process in Domžale-Kamnik WWTP. With the designed model a relatively good agreement in steady-state operation of the sludge treatment is achieved in comparison with the measurements. To get a good agreement of modelled and measured total nitrogen and ammonia nitrogen concentrations, nitrogen content of the active biomass of the influent sludge is reduced and nitrogen fraction in inerts of the digestion model is increased. Larger model deviation from the measurements was obtained only in the concentration of the suspended solids in the sludge overflow from the digestion tanks because the real digestion tanks are not completely mixed. The designed model is used to perform several simulation scenarios. Simulations show that the volumes of the sludge treatment tanks are large enough to maximize the gas production even at the maximum sludge flow rate. The gas production can be improved by increasing the sludge temperature to 55 oC. Sludge treatment can be also improved by optimizing the ratio between the digested sludge pumped to the dewatering process and the sludge overflow returned back to the plant.
COBISS.SI-ID: 24881959