Enhanced degradation of complex organic compounds in wastewater using different novel continuous flow non - Thermal pulsed corona plasma discharge reactors.

The presence of pharmaceutically active compounds (PhAcs) in water bodies is a major concern due to their persistence, biological activity, and detrimental environmental effects. The present study focuses on the application of pulsed corona plasma technology to degrade such compounds. Three different plasma reactors, namely, sequential flow plasma reactor (SFR), continuous flow top discharge plasma reactor (TDPR) and continuous flow side discharge plasma reactor (SDPR), are designed and fabricated for their performance evaluation with respect to PhAC degradation. In all the reactors, wastewater was discharged as fine droplets for better interaction between the reactive oxidizing species (ROS) generated in the system and the pollutants. Enhanced degradation of the selected pharmaceutical compounds, i.e., diclofenac (DCF) and verapamil hydrochloride (VPL), is achieved with decreased treatment time and lower energy consumption. In SFR reactor water was recycled, whereas in continuous flow reactors hydraulic retention times (HRTs) were varied. The degradation efficiency of DCF (1 mg/L) and VPL (1 mg/L) was 99 % in SDPR, at HRTs of 9 and 12 min, respectively. Deposited energies (SFR- 71 W, TDPR - 92 W, SDPR- 51 W) varied due to the difference in reactor geometries. In the SDPR reactor, 99 % degradation of mixed pollutants with an initial concentration of 10 mg/L was achieved, at a HRT of 21 min. With an input power of 51 W, good energy efficiency (EEO) of 3.8 kWh/m3 and high yield (G) of 256.2 mg/kWh were obtained. . Nitrate formation was reduced by 73.2 % in TDPR and 85.0% in SDPR (32.1-8.6 mg/L) as compared to SFR (32.1 mg/L). The operating cost estimated was 0.71 $/m3, 0.80 $/m3 and 0.67 $/m3 for SFR, TDPR and SDPR, respectively. The results clearly indicate that the continuous flow reactor with side discharge is a viable alternative to traditional plasma reactors.

Assessment of novel rotating bipolar multiple disc electrode electrocoagulation-flotation and pulsed plasma corona discharge for the treatment of textile dyes.

The current study evaluates the performance of the designed novel electrolytic reactor with rotating bipolar multiple disc electrode (RBDE) in the electrocoagulation-flotation (EC-F) process and a pulsed plasma reactor for the removal of toxic textile dyes. Two different classes of dyes, Methyl Orange (MO), an azo group of dye, and Reactive Blue 19 (RB19), a reactive group of dye, were selected. Efficient removal of both the dyes at a faster rate was obtained with the designed RBDE reactor compared to the EC-F process with static electrodes. RB19 and MO were completely decolourized (100%) within 2 min of electrolysis time with rotating and 6 min with static (non-rotating) electrodes, respectively. Similarly, the maximum chemical oxygen demand removal of 86.4% and 93.2% was obtained for RB19 and MO, respectively, with the rotating electrode EC-F process. On the other hand, complete decolourization was obtained in 10 min and 12 min of pulsed corona discharge for MO (50 mg/L) and RB19 (50 mg/L), respectively. The comparison studies of RBDE and pulsed power plasma reactor (PPT) showed that MO removal was faster than RB19 removal in both RBDE EC-F and PPT processes. Relatively long treatment time was needed for RB19 compared to MO due to its complexity of structure and high solubility. RB19 and MO were completely degraded through pulsed corona discharge without any sludge production. The results show that the designed RBDE reactor performed much better than existing conventional electrocoagulation reactors. The RBDE reactor can be used as a pre-treatment unit for industrial wastewater, which can improve the treatment efficiency and reduces the energy consumption. Plasma technology showed complete degradation of pollutant without sludge production. The formation of a wide variety of reactive oxygen species during corona discharge helps in degrading the pollutants. Plasma technology can be used as a secondary treatment system along with the RBDE as pre-treatment process for complex industrial wastewaters. This will improve the quality of treated effluent and reduce the overall cost of treatment.