Removal efficiency and energy consumption optimization for carbamazepine degradation in wastewater by electrohydraulic discharge

Abstract

Objective: The treatment of recalcitrant emerging pollutants is a major concern in wastewater treatment. The purpose of this study was the optimization of emerging recalcitrant pollutant degradation using carbamazepine as a representative pollutant. Investigations of the carbamazepine degradation in wastewater was carried out by manipulating discharge current, air flow rate, and initial concentration to maximize removal efficiency and minimize energy consumption. Method: The study utilized a three-factor at two levels factorial design with randomized central runs. Discharge current, air flow rate, and initial concentration were the independent variables while to maximize removal efficiency and minimize energy consumption were the response variables. Analysis of variance (ANOVA) was performed on the data. Results: Discharge current, air flow rate, and initial concentration significantly impacted the removal efficiency to different degrees. However, for energy consumption, only current and air flow rate were the significant variables. The highest removal efficiency obtained was 93% ± 4% for 10 and 40 mg/L initial carbamazepine concentration after 10 min of plasma treatment at a current of 0.45 A and no air flow rate. Conclusion: The plasma reactor demonstrated the capability to treat high cyclic organic chemical contaminant concentration in wastewater with possible applications in preconcentrated wastewater remediation. However, there is still room for reactor design optimization. One key area of focus is reducing treatment cost, which may be achieved theoretically, pending further experimental investigation, by introducing an alternating current power supply, which can reduce energy consumption by 50%–60%. Practitioner Points: Discharge current, air flow rate, and initial concentration all influenced the removal efficiency of carbamazepine. For energy consumption, only current and air flow rate were significant variables. Higher currents result in an improved highly reactive species and UV generation. Treatment cost per m3 for the plasma reactor is higher than established technologies. The plasma reactor in the study still requires significant optimization.