Applications of automatic control systems for chlorination and dechlorination processes in wastewater treatment plants

Industrial experience of process identification and set-point decision algorithm in a full-scale treatment plant

“…This change is proportional to changes in the respiration rate, if changes in DO concentration inside the reactor due to incoming and outgoing flows are negligible. The respiration rate is estimated as the slope of a regression line fitted to a series of DO signals (Carlsson et al, 1994;Dieu et al, 1995;Johansen et al, 1997;Sotomayor et al, 2002). However, because the relay-feedback method may experience an unexpected disturbance during the identification, the process variables may deviate from the normal steady state during the identification step.…”

“…At the same time, DO level cannot be controlled satisfactorily with a simple PID controller because the DO level depends on time-varying influent loads, time delays, sensor noise and slow dynamics, temperature, and the activity of microorganisms. Many real-time identification methods have been proposed for obtaining process information (Åströ m and Hä gglund, 1984;Dieu et al, 1995;Yoo et al, 2001). Carlsson et al (1994) used the autotuning controller suggested by Åströ m-Hä gglund to control the DO concentration in a WWTP.…”

“…Carlsson et al (1994) used the autotuning controller suggested by Åströ m-Hä gglund to control the DO concentration in a WWTP. Dieu et al (1995) used a relay-feedback method to tune the PID loop controller parameters of the programmable logic controller in the chlorination and dechlorination process. Yoo et al (2001) applied a closed-loop identification and control method to a full-scale coke WWTP.…”

<b>Artificial neural networks to control chlorine dosing in a water treatment plant

“…Mathematical modeling and implementation with artificial neural networks Dieu, Garrett Jr., Ahmad, and Young (1995) proposed a single variable Proportional-Integral-Derivative (PID) chlorine control dosage, with all the required devices, such as online analyzer free residual chlorine, PLCs and chlorine dosers, demonstrating a control loop similar to that used in WTP under analysis. Since the WTP postchlorination dosage has several variables that directly impact the FRC rate in the treated water, the use of the traditional PID controller is restricted, as reported by Escobar and Trierweiler (2013).…”