Resumen: Este trabajo constituye la primera parte de una revisión de la problemática del control y operación de estaciones depuradoras de aguas residuales (EDAR) para el tratamiento de agua residual urbana. En esta primera parte nos centramos en el modelado y simulación mientras que la segunda parte se dedica en exclusiva al control y operación. Esta depuración se realiza, mayoritariamente, mediante procesos biológicos, concretamente, mediante el denominado proceso de fangos activados. El hecho de tratar con un proceso biológico conlleva una elevada complejidad tanto desde el punto de vista de modelado como, por supuesto, de control y operación. Para poder ubicar convenientemente el problema, se presenta una caracterización de las aguas residuales urbanas y las necesidades de depuración asociadas. El control y operación descansan en gran medida en la disponibilidad de modelos apropiados y, ya hoy en día, de una elevada fiabilidad. Se presentan los modelos de la familia ASM; poniendo especial énfasis en el ASM1 que se describe en más detalle; así como las características de otras unidades de proceso como el decantador y su interconexión. En estos modelos destacan los entornos BSM de benchmarking, que han sido esenciales para todo el posterior desarrollo en la actividad de control y operación. This tutorial is the first part of a review of the problems arising with the control and operation of wastewater treatment plants (WWTP) for urban wastewater. This first part will concentrate in the modelling and simulation steps whereas the second part will cover the control and operation issues. This treatment is carried out, mainly, by biological processes. Specifically, by the so-called activated sludge process. Dealing with a biological process entails a high complexity both from the viewpoint of modelling and, of course, from what matters to control and operation. In order to properly locate the problem, a characterisation of the urban wastewater and the associated treatment needs are presented. Control and operation rely heavily on the availability of appropriate models and, today, of proved reliability. The models of the ASM family are presented; placing special emphasis on the ASM1 that is described in more detail; as well as the characteristics of other process units like the settler and its interconnection. These models highlight the BSM benchmarking environments, which have been essential for all subsequent development in the control and operation activity. Palabras clave: Estaciones depuradoras de aguas residuales, proceso de fangos activados, benchmarking, Keywords: wastewater treatment plants, activated sludge process, benchmarkin

The internal recirculation plays an important role on the different biological processes of wastewater treatment plants because it has a great influence on the concentration of pollutants, especially nutrients. Usually, the internal recirculation flow rate is kept fixed or manipulated by control techniques to maintain a fixed nitrate set-point in the last anoxic tank. This work proposes a new control strategy to manipulate the internal recirculation flow rate by applying a fuzzy controller. The proposed controller takes into account the effects of the internal recirculation flow rate on the inlet of the biological treatment and on the denitrification and nitrification processes with the aim of reducing violations of legally established limits of nitrogen and ammonia and also reducing operational costs. The proposed fuzzy controller is tested by simulation with the internationally known benchmark simulation model no. 2. The objective is to apply the proposed fuzzy controller in any control strategy, only replacing the manipulation of the internal recirculation flow rate, to improve the plant operation.Therefore, it has been implemented in five operation strategies from the literature, replacing their original internal recirculation flow rate control, and simulation results are compared with those of the original strategies. Results show improvements with the application of the proposed fuzzy controller of between 2.25 and 57.94% in reduction of total nitrogen limit violations, between 55.22 and 79.69% in reduction of ammonia limit violations and between 0.84 and 38.06% in cost reduction of pumping energy.

Due to the complex and non linear character, wastewater treatment process is difficult to be controlled. And the demand for removing the pollutant, especially for nitrogen (N) and phosphorus (P), as well as reducing the cost of wastewater treatment plant (WWTP) is an important research topic. This paper applies PI control and decentralised model predictive control control to the combined phosphorus removal Benchmark Simulation Model 1 (BSMI-P) wastewater treatment process to enhance the P removal. A default control strategy which contains two control loops and is similar to the one given by the original version of BSMI was tested on BSMI-P. In addition, linear models have been identified and model predictive controllers implemented for each one of these loops. The simulation results showed that the MPC controllers are able to the controller performance in all the three weather conditions.