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In this study, the electrochemical oxidation (EO) process was implemented and optimized to effectively decolorize and degrade wastewater containing Acid Yellow 23 (Y23). The experiments were carried out in a laboratory-scale batch cell reactor, with monopolar configuration of electrodes, made of graphite (anode) and titanium (cathode). The response surface methodology (RSM), coupled with Box-Behnken experimental design (BBD), was used to evaluate the single and interactive effects of different variables of the EO process on (1)degradation percentages of both chemical oxygen demand (%DCOD) and color (%DC) and (2)energy consumption (EC). Thus, the following experimental factors were considered: initial dye concentration (40-100mg/L), current density (10-20mA/cm2), and conductivity (1,000-4,000S/cm). Thus, the subsequent conditions were found to be optimal for decolorization and degradation of Y23: initial dye concentration = 100mg/L; current density = 20mA/cm2; and conductivity = 4,000S/cm. At these conditions, the EO process allowed to reach approximately 99% of color degradation and 76% of COD degradation. Because NaCl was used as an electrolyte, chorine formation was monitored, and its effect on %DC and %DCOD was also evaluated.

In this study, the electrochemical oxidation (EO) process was implemented and optimized to effectively decolorize and degrade wastewater containing Acid Yellow 23 (Y23). The experiments were carried out in a laboratory-scale batch cell reactor, with monopolar configuration of electrodes, made of graphite (anode) and titanium (cathode). The response surface methodology (RSM), coupled with Box-Behnken experimental design (BBD), was used to evaluate the single and interactive effects of different variables of the EO process on (1)degradation percentages of both chemical oxygen demand (%DCOD) and color (%DC) and (2)energy consumption (EC). Thus, the following experimental factors were considered: initial dye concentration (40-100mg/L), current density (10-20mA/cm2), and conductivity (1,000-4,000S/cm). Thus, the subsequent conditions were found to be optimal for decolorization and degradation of Y23: initial dye concentration = 100mg/L; current density = 20mA/cm2; and conductivity = 4,000S/cm. At these conditions, the EO process allowed to reach approximately 99% of color degradation and 76% of COD degradation. Because NaCl was used as an electrolyte, chorine formation was monitored, and its effect on %DC and %DCOD was also evaluated.

The Response Surface Methodology (RSM) was applied as a tool for the optimization of the operational conditions of the photo-degradation of highly concentrated PY12 wastewater, resulting from a textile industry located in the suburbs of Medellin (Colombia). The Box-Behnken experimental Design (BBD) was chosen for the purpose of response optimization. The photo-Fenton process was carried out in a laboratory-scale batch photo-reactor. A multifactorial experimental design was proposed, including the following variables: the initial dyestuff concentration, the H(2)O(2) and the Fe(+2) concentrations, as well as the UV wavelength radiation. The photo-Fenton process performed at the optimized conditions resulted in ca. 100% of dyestuff decolorization, 92% of COD and 82% of TOC degradation. A kinetic study was accomplished, including the identification of some intermediate compounds generated during the oxidation process. The water biodegradability reached a final DBO(5)/DQO = 0.86 value.

This work deals with the treatment of the wastewaters resulting from the process of dyeing flowers. In some local cases for growing flowers near to Medellin (Colombia), wastewater color was found to be one of the main problems in meeting local effluent standards. Wastewaters were treated by photodegradation process (which includes photocatalysis) to achieve the degradation of dyes mixture and organic matter in the wastewater. A multifactorial experimental design was proposed, including as experimental factors the following variables: pH, and the concentration of both catalyst (TiO(2)) and hydrogen peroxide (H(2)O(2)). According to the obtained results, at the optimized variables values, it is possible to reach a 99% reduction of dyes, a 76.9% of mineralization (TOC) and a final biodegradability of 0.834. Kinetic analysis allows proposing a pseudo first order reaction for the reduction, the mineralization, and the biodegradation processes.

The elimination of total and fecal coliforms, from raw surface water, was carried out by electrochemical oxidation using either boron doped diamond (BDD/Ti) or graphite (GP) anodes, in a chloride-free medium. The optimal values of the operation parameters, maximizing the coliform elimination percentage, were determined using statistical experimental design. The current density ( j: 2-20 mA/cm2), the conductivity (s: 500-900 µS/cm) and the anode materials (An) were considered as variables to perform the Box-Behnken experimental design together with the response surface methodology analysis for optimization. The statistical analysis indicated that, in the evaluated range, the disinfection efficiency increased with an increase in j and decreased with an increase in s. The following optimal conditions for the elimination of total and fecal coliforms were found: j: 10 mA/cm2, s: 500 µS/cm and BDD/Ti used as anode material. The BDD/Ti electrode let to achieve complete coliform elimination after ca. 20 min of reaction while the GP one needed ca. 27 min. In water treated with both BDD/Ti and GP anode, after 7 days, any coliforms growth was observed. As a result of the oxidation process, the total organic carbon and nitrite concentration decreased while nitrate concentration increased. © IWA Publishing 2018.

In this study, the electrochemical oxidation (EO) process was implemented and optimized to effectively decolorize and degrade wastewater containing Acid Yellow 23 (Y23). The experiments were carried out in a laboratory-scale batch cell reactor, with monopolar configuration of electrodes, made of graphite (anode) and titanium (cathode). The response surface methodology (RSM), coupled with Box-Behnken experimental design (BBD), was used to evaluate the single and interactive effects of different variables of the EO process on (1)degradation percentages of both chemical oxygen demand (%DCOD) and color (%DC) and (2)energy consumption (EC). Thus, the following experimental factors were considered: initial dye concentration (40-100mg/L), current density (10-20mA/cm2), and conductivity (1,000-4,000S/cm). Thus, the subsequent conditions were found to be optimal for decolorization and degradation of Y23: initial dye concentration = 100mg/L; current density = 20mA/cm2; and conductivity = 4,000S/cm. At these conditions, the EO process allowed to reach approximately 99% of color degradation and 76% of COD degradation. Because NaCl was used as an electrolyte, chorine formation was monitored, and its effect on %DC and %DCOD was also evaluated.

An electrocoagulation process was used for the treatment of oily wastewater generated from an automotive industry in Medellin (Colombia). An electrochemical cell consisting of four parallel electrodes (Fe and Al) in bipolar configuration was implemented. A multifactorial experimental design was used for evaluating the influence of several parameters including: type and arrangement of electrodes, pH, and current density. Oil and grease removal was defined as the response variable for the statistical analysis. Additionally, the BOD(5), COD, and TOC were monitored during the treatment process. According to the results, at the optimum parameter values (current density = 4.3 mA/cm(2), distance between electrodes = 1.5 cm, Fe as anode, and pH = 12) it was possible to reach a c.a. 95% oils removal, COD and mineralization of 87.4% and 70.6%, respectively. A final biodegradability (BOD(5)/COD) of 0.54 was reached.

The elimination of total and fecal coliforms, from raw surface water, was carried out by electrochemical oxidation using either boron doped diamond (BDD/Ti) or graphite (GP) anodes, in a chloride-free medium. The optimal values of the operation parameters, maximizing the coliform elimination percentage, were determined using statistical experimental design. The current density ( j: 2-20 mA/cm2), the conductivity (s: 500-900 µS/cm) and the anode materials (An) were considered as variables to perform the Box-Behnken experimental design together with the response surface methodology analysis for optimization. The statistical analysis indicated that, in the evaluated range, the disinfection efficiency increased with an increase in j and decreased with an increase in s. The following optimal conditions for the elimination of total and fecal coliforms were found: j: 10 mA/cm2, s: 500 µS/cm and BDD/Ti used as anode material. The BDD/Ti electrode let to achieve complete coliform elimination after ca. 20 min of reaction while the GP one needed ca. 27 min. In water treated with both BDD/Ti and GP anode, after 7 days, any coliforms growth was observed. As a result of the oxidation process, the total organic carbon and nitrite concentration decreased while nitrate concentration increased. © IWA Publishing 2018.

In this study, the sequential Chemical Coagulation-Electro-Oxidation (CC-EO) process was proposed as an alternative for the treatment of an industrial textile wastewater. Complete characterization of the effluent was made in the terms of its organic load (Total Organic Carbon (TOC), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD5)), biodegradability (BOD5/COD ratio) and solids content (total solids and turbidity). For CC, the jar test was used to determine both the most favorable dosage of coagulant and pH of the process (i.e., 600 mg/L of Al2(SO4)3 at pH of 9.3). CC let to remove ca. 93% of turbidity, 53% of COD and 24% of TOC. It also increased BOD5/COD ratio of raw textile wastewater from 0.16 to 0.27. Next, CC effluent was treated by EO. Its performance was optimized using Box-Behnken experimental Design and Response Surface Methodology. The following EO optimal conditions were found: current density = 15 mA/cm2, conductivity = 4.7 mS/cm and pH = 5.6. At these conditions, the sequential CC-EO process removed 100% of color, 93.5% of COD, and 75% of TOC after 45 min of electrolysis with an estimated operating cost of 6.91 USD/m3. Moreover, the CC-EO process yield a highly oxidized (Average Oxidation State, AOS = 2.3) and biocompatible (BOD5/COD >0.4) effluent. © 2018 Elsevier Ltd

In this study, the sequential Chemical Coagulation-Electro-Oxidation (CC-EO) process was proposed as an alternative for the treatment of an industrial textile wastewater. Complete characterization of the effluent was made in the terms of its organic load (Total Organic Carbon (TOC), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD5)), biodegradability (BOD5/COD ratio) and solids content (total solids and turbidity). For CC, the jar test was used to determine both the most favorable dosage of coagulant and pH of the process (i.e., 600 mg/L of Al2(SO4)3 at pH of 9.3). CC let to remove ca. 93% of turbidity, 53% of COD and 24% of TOC. It also increased BOD5/COD ratio of raw textile wastewater from 0.16 to 0.27. Next, CC effluent was treated by EO. Its performance was optimized using Box-Behnken experimental Design and Response Surface Methodology. The following EO optimal conditions were found: current density = 15 mA/cm2, conductivity = 4.7 mS/cm and pH = 5.6. At these conditions, the sequential CC-EO process removed 100% of color, 93.5% of COD, and 75% of TOC after 45 min of electrolysis with an estimated operating cost of 6.91 USD/m3. Moreover, the CC-EO process yield a highly oxidized (Average Oxidation State, AOS = 2.3) and biocompatible (BOD5/COD >0.4) effluent. © 2018 Elsevier Ltd

In this work, the Box–Behnken experimental design and the surface response methodology were applied for the optimization of the operational conditions of the electro-catalytic degradation of wastewaters, resulting from a local textile industry. The experiments were carried out in a laboratory scale batch cell reactor, with monopolar configuration, and electrodes made of boron-doped diamond (anode) and titanium (cathode). The multifactorial experimental design included the following variables: current density (i: 5–10 ?mA/cm2), pH (3–7), and submerged cathode area (CA: 8–24 ?cm2). To determine the process efficiency, the degradation percentage of: the chemical oxygen demand (%DCOD), the total organic carbon (%DTOC) and the color (%DC) were defined as response variables. The following optimal conditions for the electro-oxidation (EO) process were obtained: i ?= ?10 ?mA/cm2, pH = 3 and CA ?= ?16 ?cm2, reaching ca. 92 ?% of DC, 37 ?% of DCOD and 31 ?% of DTOC. The electro-Fenton (EF) and photo-electro-Fenton (PEF) processes were also evaluated at EO optimal conditions. For the EF process, with addition of iron (0.3 ?mM), the %DC, %DCOD and %DTOC was enhanced to 95, 52 and 45 ?%, respectively. For the PEF process (UV ?= ?365 ?nm), it was possible to reach 98 ?%DC, 56 ?%DCOD and 48 ?%DTOC. © 2014, Springer Science+Business Media Dordrecht.

In this work, the Box-Benkhen experimental Design (BBD) was applied for the optimization of the parameters of the electrocatalytic degradation of wastewaters resulting from a phenolic resins industry placed in the suburbs of Medellin (Colombia). The direct and the oxidant assisted electro-oxidation experiments were carried out in a laboratory scale batch cell reactor, with monopolar configuration, and electrodes made of graphite (anode) and titanium (cathode). A multifactorial experimental design was proposed, including the following experimental variables: initial phenol concentration, conductivity, and pH. The direct electro-oxidation process allowed to reach ca. 88% of phenol degradation, 38% of mineralization (TOC), 52% of Chemical Oxygen Demand (COD) degradation, and an increase in water biodegradability of 13%. The synergetic effect of the electro-oxidation process and the respective oxidant agent (Fenton reactant, potassium permanganate, or sodium persulfate) let to a significant increase in the rate of the degradation process. At the optimized variables values, it was possible to reach ca. 99% of phenol degradation, 80% of TOC and 88% of COD degradation. A kinetic study was accomplished, which included the identification of the intermediate compounds generated during the oxidation process.

In this work, TiO2 (Degussa, P-25) supported on calcium alginate pearls was evaluated as catalyst for the photocatalytic inhibition of pathogenic microorganisms. Considering that water samples were taken directly from a natural source, a primary treatment (coagulation, sedimentation and filtration) was executed to remove solids and impurities. Photocatalytic experiments were carried out in two types of laboratory scale equipments, one using an annular UV irradiated reactor and the other a solar UV parabolic collector, both operated in the fluidized bed mode. H2O2 was included to the reactive mixture in order to enhance the photodegradation rate. The Response Surface Methodology and the Box-Behnken experimental design techniques were applied as tools for the optimization of the operational conditions of the UV water purification system. Thus, the influence of UV radiation, TiO2 dose and H2O2 concentration on the faecal and total coliform percentage degradation were statistically analysed. The following optimal operational conditions were found: UV radiation = 310 nm, TiO2 dose = 0.2 g/L and H2O2 concentration = 30 mg/L. After water treatment at optimized conditions, total microorganism growing inhibition was observed. Additional experiments allowed proving the reusability of the immobilized catalyst. © 2014 Science & Technology Network, Inc.