Assessment of Electrocoagulation Control System Strategy in Textile Wastewater Treatment Plant

Abstract

Electrocoagulation is a method of wastewater treatment that applies an electrical current into the liquid to coagulate the suspended particles. This study assessed two control strategies for electrocoagulation systems in wastewater treatment in terms of dynamic performances and energy consumptions. The first control strategy used the electrical current as a manipulated variable, and the second used the waste liquid flowrate instead. For either strategy, the controlled output was the turbidity of the product liquid. The assessment was conducted in an experimental setting, in a laboratory-scale, continuous pilot plant. The experiment began with the identification of the dynamic characteristics of the electrocoagulation process due to the combined changes in the electrical current between 1.8-5.2 Ampere and the changes in waste flowrate between 10.37-14.67 ml/s. First-Order-Process-with-Time-Delay equations approximated these processes. The statistical Analysis of Variance was used to select the best process condition to compare two control strategies. The associated Proportional Integral controllers were designed and applied for either strategy. The experiment showed that manipulating electrical current yield 7.48% longer settling time, but with significantly lower energy consumption throughout the electrocoagulation process. The result highlighted the benefit of using electrical current as of the manipulated variable in the electrocoagulation process in the pilot plant.