The use of appropriate and automatized strategies to manage Wastewater Treatment Plants (WWTPs) is a feasible way to save energy maintaining the depurative efficiency. Operating cost for treated water in small-medium plants are typically higher than those of large plants and this depends on two aspects: firstly in small plants influent load variations are higher than in larger plants, secondly the instrumentation installed is minimal. In this context this work aims to propose control strategies applicable to small and medium size WWTPs with biological secondary treatment phase fed on municipal sewage, in order to optimize the operative costs and maintain the outflow pollutants concentrations under the law thresholds. The study is based on data collected on a conventional Activated Sludge (CAS) continuous flow pilot scale plant, located inside the area of a municipal WWTP, designed for 1500 P.E. In particular, the mathematical model of the plant has been implemented, calibrated and validated and several dynamic simulations have been carried out in order to set the procedures of a novel management policy involving both the Nitrification and the Denitrification processes, approaching in a preliminary step the Business Process Management Notation (BPMN). According to this policy, fixed the estimated daily total nitrogen concentration in the effluent, the modulation of the set point of NH4+ concentration in oxidation tank, using proportional-integral (PI) cascade controllers (ammonium – dissolved oxygen), allows to optimize the energetic cost for the nitrification process. Furthermore, the plant behaviour has been simulated combining four internal recirculation flow rates values with the PI set-points defined for the Nitrification tank. The results obtained permit to combine the plant variables to obtain the respect of the law thresholds at the maximum efficiency.
MODELLING OF CONTROL STRATEGIES AND POLICIES TO MANAGE URBAN WASTEWATER TREATMENT PLANTS
FIORENTINO, CARMINE;MANCINI, MAURIZIO;
2016
Abstract
The use of appropriate and automatized strategies to manage Wastewater Treatment Plants (WWTPs) is a feasible way to save energy maintaining the depurative efficiency. Operating cost for treated water in small-medium plants are typically higher than those of large plants and this depends on two aspects: firstly in small plants influent load variations are higher than in larger plants, secondly the instrumentation installed is minimal. In this context this work aims to propose control strategies applicable to small and medium size WWTPs with biological secondary treatment phase fed on municipal sewage, in order to optimize the operative costs and maintain the outflow pollutants concentrations under the law thresholds. The study is based on data collected on a conventional Activated Sludge (CAS) continuous flow pilot scale plant, located inside the area of a municipal WWTP, designed for 1500 P.E. In particular, the mathematical model of the plant has been implemented, calibrated and validated and several dynamic simulations have been carried out in order to set the procedures of a novel management policy involving both the Nitrification and the Denitrification processes, approaching in a preliminary step the Business Process Management Notation (BPMN). According to this policy, fixed the estimated daily total nitrogen concentration in the effluent, the modulation of the set point of NH4+ concentration in oxidation tank, using proportional-integral (PI) cascade controllers (ammonium – dissolved oxygen), allows to optimize the energetic cost for the nitrification process. Furthermore, the plant behaviour has been simulated combining four internal recirculation flow rates values with the PI set-points defined for the Nitrification tank. The results obtained permit to combine the plant variables to obtain the respect of the law thresholds at the maximum efficiency.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
