Wastewater Neutralization Control Based in Fuzzy Logic:  Simulation Results

Abstract

Neutralization is a technique widely used as a part of wastewater treatment processes. Due to the importance of this technique, extensive study has been devoted to its control. However, industrial wastewater neutralization control is a procedure with a lot of problemsnonlinearity of the titration curve, variable buffering, changes in loadingand despite the efforts devoted to this subject, the problem has not been totally solved. In this paper, the authors present the development of a controller based in fuzzy logic (FLC). In order to study its efectiveness, it has been compared, by simulation, with other advanced controllers (using identification techniques and adaptive control algorithms using reference models) when faced with various types of wastewater with different buffer capacity or when changes in the concentration of the acid present in the wastewater take place. Results obtained show that FLC could be considered as a powerful alternative for wastewater neutralization processes.

Iterative nonlinear model predictive control. Stability, robustness and applications

“…A self-tuning controller is described in Babuska et al (2002). Adaptive nonlinear control strategies (Henson and Seborg, 1994), modelbased (Sing and Postlethwaite, 1997) and fuzzy logic controllers (Garrido et al, 1997) have also been used.…”

Wastewater Neutralization Control Based on Fuzzy Logic: Experimental Results

“…In this test the controller was evaluated using a simulation run where the process gain changed throughout the course of the simulation. To simulate the behavior of the pH evolution throughout the experimental runs, a mathematical model was developed based on that proposed by Garrido et al (1997). This model was refined in order to have the possibility of reproducing the experimental conditions of dead times and specific water compositions.…”

“…Finally, a numeric output is obtained (Kosko, 1992;Cox, 1994). Garrido et al (1997) compared the application of a fuzzy controller with the advanced controllers proposed by Riggs et al (1990), Gaulian et al (1990), and Kurtz (1985). Results obtained showed that FLC could be considered a valuable tool in the wastewater neutralization processes testing them in computer simulations.…”

“…The objective of this paper was to test a controller based on fuzzy logic to a wastewater neutralization process. To achieve the objective, a controller based on the algorithm proposed by Garrido et al (1997) with an adaptive factor to tune fuzzy response and to improve robustness under variable buffering capacity conditions was developed. The proposed controller was tested experimentally in a treatment plant and with simulations under different conditions: variable buffering capacities of the wastewater, changes in the acid concentration of the wastewater, and switches between acids.…”

DYNAMIC FUZZY ADAPTIVE CONTROLLER FOR pH

“…Model-based fuzzy controllers, namely an internal model controller (Postlethwaite, 1994), nonlinear model predictive controller (Peng and Jang, 1994), a relational model based controller (Sing and Postlethwaite, 1996), and a dynamic fuzzy learning controller (Venkateswarlu and Gangiah, 1996), are also reported for different chemical processes. Recently, Garrido et al (1997) applied a rule-based fuzzy logic controller for wastewater neutralization. This considers only input concentration changes in acid wastewater to maintain its pH at 7.…”