Electrochemical degradation of ciprofloxacin through a DoE-driven optimization in a filter-press type reactor under batch recirculation mode.

In this work, the electrochemical degradation of ciprofloxacin (CIP) was studied in a filter-press-type reactor without division in a batch recirculation manner. For this purpose, two boron-doped diamond (BDD) electrodes (as cathode and anode) were employed. Also, the optimal operating conditions were found by response surface methodology (RSM) following a central composite face-centered design with three factors, namely current intensity (i), initial pH (pH0), and initial concentration ([C]0) with two responses, namely remotion efficiency (η) and operating cost. Optimal operating conditions were i = 3 A, pH0 = 8.49, and [C]0 = 33.26 mg L-1 within an electrolysis time of 5 h, leading to a maximum removal efficiency of 93.49% with a minimum operating cost of $0.013 USD L-1. Also, a TOC analysis shows an 80% of mineralization extent with an energy consumption of 5.11 kWh g-1 TOC. Furthermore, the CIP degradation progress was followed by mass spectrometry (LC/MS) and a degradation pathway is proposed.

Convex optimization for maximizing the degradation efficiency of chloroquine in a flow-by electrochemical reactor.

The degradation efficiency of chloroquine phosphate (CQ), an anti-COVID-19 drug, was investigated in a flow-by electrochemical reactor (FBER) provided with two boron-doped diamond (BDD) electrodes (as cathode and anode) under batch recirculation mode. A central composite rotatable design (CCRD) was run down to model and assess the influence of initial pH in an interval of 3.71 to 11.28, the current density in an interval of 34.32 to 185.68 mA cm-2, and liquid volumetric flow rate in an interval of 0.58 to 1.42 L min-1, and conduct the convex optimization to obtain the maximum degradation efficiency. Experimental results were modeled through a second-order polynomial equation having a determination coefficient (R2) of 0.9705 with a variance coefficient of 1.1%. Optimal operating conditions found (initial pH of 5.38, current density (j) of 34.4 mA cm-2, and liquid flow rate (Q) of 1.42 L min-1) led to a global maximum degradation efficiency, COD removal efficiency, and mineralization efficiency of 89.3, 51.6 and 53.1%, respectively, with an energy consumption of 0.041 kWh L-1 within 9 h of treatment. Additionally, a pseudo-zero-order kinetic model was demonstrated to fit the experimental data and the calculated pseudo-zero-order kinetic constant (kapp) was 13.14 mg L-1 h-1 (2.54 × 10-5 mol dm-3 h-1). Furthermore, the total operating cost was of 0.47 US$ L-1. Finally, this research could be helpful for the treatment of wastewater containing an anti-COVID-19 drug such as CQ. Supplementary Information: The online version contains supplementary material available at 10.1007/s10008-023-05452-7.

Parametric optimization of domestic wastewater treatment in an activated sludge sequencing batch reactor using response surface methodology.

In this work, the parametric optimization of real domestic wastewater treated in an activated sludge sequencing batch reactor (SBR) was performed by means of the response surface methodology (RSM). The influences of influent organic matter concentration as chemical oxygen demand (CODinf), biomass concentration (Xs) and aeration time (t) on the COD, organic matter removal efficiency as COD (η) and sludge volume index (SVI) were determined to evaluate the performance of activated sludge SBR. The results showed that organic matter efficiency and maximum SVI were obtained at a t of 12 h, 300 mg L-1 of CODinf and 2000 mg L-1 of Xs. The SBR-activated sludge exhibited a η of 73% and an SVI of 119 mL g-1. Both values indicated a very good performance. Furthermore, the COD of the effluent under these conditions complied with Mexican regulations for wastewater discharged into water bodies.