OBJECTIVEThe treatment of recalcitrant emerging pollutants is a major concern in wastewater treatment. The purpose of this study was the optimisation 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 maximise removal efficiency and minimise energy consumption.METHODThe study utilised a three factor at two levels factorial design with randomised central runs. Discharge current, air flow rate, and initial concentration were the independent variables while to removal efficiency and minimise energy consumption were the response variables. ANOVA analysis was performed on the data.RESULTSDischarge 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 minutes of plasma treatment at a current of 0.45 A and no air flow rate.CONCLUSIONThe reactor demonstrated the capability to treat high cyclic organic chemical contaminant concentration in wastewater with possible applications in pre‐concentrated wastewater remediation. However, there is still room for reactor design optimisation. 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%.

The United Nations, through its Sustainable Development Goals, have identified access to clean water as one of the challenges facing society. With reported global deaths exceeding 1 million annually linked to untreated water consumption, which is usually contaminated by pathogenic micro-organisms, further research continues in water disinfection. The direct generation of non-thermal plasma in water is a promising method for the inactivation of disease-causing bacteria present in the wastewater. This study explored the efficacy of plasma in the inactivation of different bacterial densities (4.0×104, 1.5×105, and 2.5×107 CFU/mL) using a 500 mL plasma batch reactor operating at atmospheric pressure. The plasma discharge was generated in water by a Technix-SR-10R-5000 high voltage direct current power supply in negative polarity with a set current of 0.45 A and a maximum pre-set ignition voltage of 9 kV. The electrodes used in the discharge was a copper material. A bacterial culture of Escherichia coli ATCC® 25922TM (E.coli) was used as a model for the direct plasma discharge. The study further investigated the contribution of copper ions (0.4 and 0.7 mg/L) released into the water during treatment by having two control reactors that were not exposed to plasma. The results show a complete inactivation at 180 seconds for the bacterial densities from 4.0×104 to 2.5×107 CFU/mL. The results from this study indicated the potential of a direct electric discharge in handling water source with high-bacteria densities.