ABSTRACT
This paper proposes the use of predictive optimal control as a suitable methodology to manage efficiently transport water networks. The predictive optimal controller is implemented using MPC control techniques. The Arrêt-Darré/Arros dam-river system located in the Southwest region of France is proposed as case study. A high-fidelity dynamic simulator based on the full Saint-Venant equations and able to reproduce this system is developed in MATLAB/SIMULINK to validate the performance of the developed predictive optimal control system. The control objective in the Arrêt-Darré/Arros dam-river system is to guarantee an ecological flow rate at a control point downstream of the Arrêt-Darré dam by controlling the outflow of this dam in spite of the unmeasured disturbances introduced by rainfalls incomings and farmer withdrawals.
Subject(s)
Models, Theoretical , Rivers , Water Movements , Computer Simulation , France , Geography , RainABSTRACT
This paper presents the theoretical basis and the main results obtained during the development and full-scale experimental validation of the new supervisory control strategy designed for the Galindo-Bilbao wastewater treatment plant (WWTP). The different phases of the project have been carried out over the last 8 years, combining model simulations, pilot-plant experimentation and full-scale validation. The final control strategy combines three complementary control loops to optimise the nitrogen removal in pre-denitrifying activated sludge plants. The first controller was designed to maintain the average concentration of the ammonia in the effluent via the automatic selection of the most appropriate DO set point in the aerobic reactors. The second control loop optimises the use of the denitrification potential and finally, the third control loop maintains the selected amount of biomass in the biological reactors by automatic manipulation of the wastage rate. Mobile-averaged windows have been implemented to incorporate commonly used averaged values in the control objectives. The performance of the controllers has been successfully assessed through the full-scale experimental validation in one of the lines of the WWTP.
Subject(s)
Waste Disposal, Fluid/methods , Air Movements , Ammonia/analysis , Automation , Bioreactors , Feedback , Nitrates/analysis , Oxygen/analysis , Sewage , SpainABSTRACT
This paper presents a new model for the dynamic prediction of water quality in rivers using in-series continuously stirred tank reactors (CSTR) and process transformations based on the IWA RWQM1. The transport model introduces a new parameter f (fraction of solids that are not retained in the in-series reactors) that splits hydraulic and solids retention times, regulating the transport of particulate substances along the river stretch. The characterization of the model components is based on elemental mass fractions, and closed mass balance is guaranteed for each process transformation. The resulting model has been implemented in the new simulator CalHidra 2.0 and applied to a branch of the Tajo River in the Madrid area. The spatial profiles of ammonium, nitrates, and dissolved oxygen in different seasonal periods have been used to calibrate the model. The proposed model also has shown its usefulness for exploring the evolution of the water quality in the Tajo River under different scenarios.
Subject(s)
Rivers/chemistry , Water Supply/standards , Computer Simulation , Geography , Seasons , SpainABSTRACT
This paper presents a new sensitivity analysis methodology for Activated Sludge WWTPs. It is based on both (a) the calculation of the range of "manipulated input variables" that satisfy the restrictions imposed on the "output variables" and (b) on the computation of isolines of the output variables inside the feasible operating space. This analysis allows a more precise description of the operating constraints, facilitates the understanding of the steady-state behaviour of the process and detects possible areas where the process is very sensitive to small disturbances. The feasible operating space for two Activated Sludge WWTP processes for CN removal (RDN, DRDN), using SRT and DO level as "input variables" as well as effluent quality and exploitation costs as the main "output variables" is studied. The proposed methodology facilitates the selection of the appropriate operational strategy and the design of automatic controllers. Some examples of the application of this methodology for the design of automatic controllers in a real WWTP are briefly presented.
Subject(s)
Models, Theoretical , Sewage , Waste Disposal, Fluid/methods , Ammonia/analysis , Automation/instrumentation , Automation/methods , Bioreactors , Equipment Design , Kinetics , Oxygen/analysis , Spain , Waste Disposal, Fluid/instrumentationABSTRACT
This paper presents a mathematical formulation for the optimum design of a new activated sludge WWTP. The WWTP optimum design problem has been formulated as a Mathematical Programming problem, which is solved through a nonlinear optimisation method. The plant model has been based on the ASM1. The minimum volume of the biological reactors and the minimum total cost (including construction and exploitation costs) have been considered as optimisation criteria. Some practical results are also included, using as a case study the design of the second stage of the Galindo-Bilbao WWTP.
