Treatment of wastewater containing fuchsin by electro-oxidation / photo-electro-cupro-fenton processes.

Application of the hybrid electrocoagulation–electrooxidation process for the degradation of contaminants in acidified biodiesel wastewater

Coupling electrocoagulation with electro-oxidation for COD and phosphorus removal from industrial container wash water

Reusing hemodialysis wastewater (HWW) is more difficult due to its higher conductivity (salinity) and the need for an iterative RO or adsorption process. It can therefore be challenging and technologically laborious. In this context, this study aimed to investigate the possibility of treating HWW by combining electro-coagulation (EC) and electro-oxidation (EO) processes and adsorption as the best technologies to achieve efficient removal of dissolved micropollutants. In this work, the application of electro-coagulation/electro-oxidation processes using, respectively, aluminum and platinum electrodes combined with adsorption onto active carbon to treat HWW was studied. In the EC process, high removal of phosphate ions and chemical oxygen demand (COD) was observed. In the EO process, the COD removal performance, total nitrogen, and Mg were significant and reached 100, 83, and 89%, respectively, after 100 min of treatment. The estimated energies required to treat HWW by EC and/or EO were approximately 0.7 kWh/m3 and 0.05 kWh/m3, respectively. While the EO and EC processes used for COD removal from HWW showed almost similar performances, the EO process seems to consume less energy. Therefore, electrochemical removal of HWW can be successfully performed using the EO process and activated carbon (AC) for the complete removal of COD and the mineralization of pharmaceutical residues. The experimental results showed that the coupling of the three processes (EC–EO–AC) provides treated water that can be reused in agriculture due to its less sodium absorption ratio (SAR) value and might be an alternative method of wastewater treatment responding to the concept of green dialysis.

A tube-in-tube membrane microreactor for tertiary treatment of urban wastewaters by photo-Fenton at neutral pH: A proof of concept

Adsorption of synthetic cationic dyes from water (experimental, DFT and Monte Carlo studies) and treatment of real industrial wastewater using dextrose compound-modified layered double hydroxide

The catalysts such as Fe, Bi2O3, and Fe-doped Bi2O3 were synthesized for the sonophotocatalytic treatment of synthetic dye and real textile wastewater. The resultant catalysts were characterized for its size and uniform shape using x-ray diffractogram (XRD) and scanning electron microscopy (SEM) which signified the nanorod shape formed Bi2O3. The higher ultraviolet light absorbance capacity of the catalysts was also evident using diffuse reflectance spectroscopy (DRS). Initially, the effect of conventional parameters such as initial pH, gas bubbling (argon, oxygen, air and nitrogen) and oxidant addition (H2O2 and peroxymonosulfate) in the presence of sonolysis (22 and 37kHz frequency) and photolysis (UV-C light) on 10ppm Basic Brown 1 dye was studied. The results showed that highest decolorization of 62% was attained for 3g/L peroxymonosulfate under 37kHz frequency sonolysis treatment. Secondly, with the catalyst study, highest of 46% dye color removal was obtained with 4g/L Fe under 37kHz frequency sonolysis treatment. The sonophotocatalytic treatment of dye with Fe-doped Bi2O3 catalyst in combination with peroxymonosulfate showed highest color removal of 99%. Finally, the sonophotocatalytic treatment of real textile wastewater in the presence of 3g/L Fe-doped Bi2O3 and 6g/L peroxymonosulfate reduced the total organic carbon (TOC) and chemical oxygen demand (COD) level to 77 and 91%, respectively, in 180min. The reported treatment process was found to treat the synthetic dye and real textile wastewater effectively.

Removal of pharmaceutical compounds from real urban wastewater by a continuous bio-electrochemical process at pilot scale

A comparative study of free chlorine activated by Fe+2 and UV C light catalysts in the treatment of real and simulated textile wastewater: Optimization, reactive species and phytotoxicity assessment

Today, water and wastewaters are effectively treated with many treatment technologies. However, there are deficiencies in the integration of treatment technologies with renewable energy sources. In this study, the integration of solar energy, one of the renewable energy sources, into electrooxidation (EO) process, which is one of the new generation advanced wastewater treatment techniques, is provided. Parameters affecting the EO process such as pH, current density (C.D.) and electrolysis time (E.T.) was optimized by Box Behnken Design (BBD) on elimination of soluble Chemical Oxygen Demand (sCOD) from metal processing wastewater. The study also tried to determine the optimum conditions for the treatment of metal processing wastewater with EO process by developing different scenarios. The scenario in which the energy requirement was 18.33 kWh/m3 and the COD removal efficiency was 75.23%, i.e. the scenario that maximizes the COD removal efficiency and minimizes the energy consumption (E.C.), is considered to be appropriate. In this case, the optimum pH for the EO process was 5, C.D. was 80 A/m2, E.T. was 22.15 minutes with a desirability of 1. At the optimum conditions (for the 2nd scenario), the E.C. of the EO process was fulfilled from solar panel in a ratio of 15% and 318% in overcast and sunny weather, respectively. Thus, it has been determined that the solar panel integrated EO process is an approach that reduces E.C. and accordingly operating cost, and also has the potential to obtain enough energy to be stored especially in sunny weather.

The elimination of pollutants in real water and wastewater is a challenge for the successful application of electrooxidation processes (EOPs). The presence of inorganic salts in the reaction medium is of great relevance during EOPs, with active participation in the electrochemical reactions. A revision of the reported devices used in the decontamination and disinfection of real wastewater demonstrated the main drawbacks of efficiently removing pollutants. However, the combination of photocatalytic processes with electrochemical technologies has been explored to improve overall efficiency and reduce energy consumption. A wide variety of materials, mainly metals, polymers, carbon and graphite derivatives, oxides, and MOFs, as well as their combinations, have been applied to electrodes and photoactive coatings. The deposition of the active layer has been enriched with novel designs, including porous hierarchical growth and 3D printing. The use of powerful characterization techniques allows for the study of the composition, structure, surface, and photo- and electrochemical performance of the fabricated electrodes. The simultaneous optimization of the operating conditions, parameters, and reactors must be specifically defined according to each water matrix. This approach will increase the efficiency of the whole process and contribute to cost savings. Economic contributions have been revised to calculate the cost of wastewater treatment.

The wide utilization of zinc oxide nanoparticles (ZnO NPs) in many products could cause their release into wastewater treatment plants. Although the potential effects of ZnO NPs on synthetic wastewater treatment have been studied, reports concerning their impacts on biological nitrogen (N) and phosphorus (P) removal from real wastewater are sparse, and the related mechanisms of these effects are still unclear. In this study, the influences of ZnO NPs on nitrogen and phosphorus removal from real municipal wastewater were investigated, and the results were compared with those using synthetic wastewater. The data showed that 50 mg/L ZnO NPs did not affect the settleability and membrane integrity of activated sludge fed with real or synthetic wastewater. Although the deterioration of N and P removal from both wastewaters was observed, the ZnO NPs-induced inhibition to real wastewater treatment was smaller than that to synthetic wastewater treatment (36% versus 100% inhibition to phosphorus removal). Fluoresce...

Petrochemicals require a large volume of water for their operation, which results in the production of a large volume of wastewater. Treatment of petrochemical wastewater is an important process before discharging it into the environment. This research examines the treatment of real petrochemical wastewater using the electrochemical oxidation process. Direct anodic oxidation is an effective advanced electrochemical oxidation process (AEOP), with different electrodes using a parallel plate electrochemical reactor. Four types of real wastewater were received from different petrochemical units were treated by AEOP. Real wastewater samples with chemical oxygen demand (COD) concentrations ranging from 20,450 to 52,300 mg/l. The main goal of this research is to make electrodes of Mixed Metal Oxide (MMO), which can reduce the treatment time and electricity consumption for oxidation, greater stability of the surface of the electrodes. Investigation of the rate constant kinetics shows that high COD removal efficiency can be achieved following the pseudo-second order reaction rate (R2 > 98%). When the wastewater pH is less than 5, COD removal efficiency is higher and the treatment process will be successful, which succeeded in removing 79% COD, but in alkaline wastewater, COD reduction efficiency was not satisfactory. The electricity consumption for 79% removal during 6 min was 117 kWh/m3. As a result, due to the very short time of the process (6 min), it can be used as one of the pre-treatment steps of petrochemical wastewater with acidic pH.

The object of the study was the process of coagulation treatment of wastewater of leather industry enterprises. The treatment of samples of real wastewater from a leather production was investigated. Such wastewater is characterized by high concentrations of pollutants of varying degrees of dispersion, which is due to the use of a large number of various chemicals in the leather production process. During technological operations related to the skinning and processing of skins, these substances enter the wastewater, which is discharged into the sewer. A peculiarity of leather production wastewater is large fluctuations in composition and volume, high concentrations of pollutants, and an increased content of suspended solids. Such waters have certain toxicity. The existing methods of wastewater treatment of leather industry enterprises do not provide the necessary treatment efficiency, do not allow to create a closed circulation of water at enterprises, to use or regenerate valuable components of wastewater, and to ensure their economically feasible disposal. Therefore, the research is aimed at improving the process of coagulation wastewater treatment of leather factories using mathematical modeling and optimization methods. This will make it possible to modernize existing wastewater treatment schemes. The experiments were carried out on the Niva Jar-test laboratory unit, which allows simultaneous examination of 6 samples. Samples of wastewater from leather production after the fattening-filling and dyeing stages were studied. The effectiveness of the coagulation process was determined by the degree of wastewater treatment. The factors were analyzed and the intervals of variation of factors that have a significant impact on the process of coagulation treatment of wastewater from leather factories were established. An experiment plan was drawn up and implemented in order to study the effect of coagulants based on aluminum and ferrum, as well as flocculants on the quality of wastewater treatment. The choice of quality indicators of the coagulation process is substantiated. A statistical analysis of the results of experimental studies was performed, a correlational analysis of the interdependence of parameters and indicators of the quality of the coagulation process was performed. Aluminum-based coagulant has been found to be more effective than iron-based coagulant. The results of mathematical modeling were used to determine the optimal parameters of the coagulation process: pH 10, coagulant dose – 2.5 g/dm3, flocculant dose – 100 mg/dm3.

Synthetic hospital wastewater treatment by coupling submerged membrane bioreactor and electrochemical advanced oxidation process: Kinetic study and toxicity assessment

The research aims to develop an advanced electrooxidation process for decolorization of recalcitrant dye. To enhance the radical formation, a combination of UV irradiation and electrooxidation (UV/EO) is used. Methylene Blue (MB), Rhodamine B (RB) and Congo Red (CR) dyes were used as model compounds to represent recalcitrant dyes. The performance of UV/EO process was investigated under various operating factors (i.e., current density (CD), voltage, pH, NaCl, anodic material), and compared with chlorination, UV irradiation, and electrooxidation (EO) process. MB was the highest resistant dye to the UV/EO process. The UV/EO process exhibited a synergistic effect on decolorization, and it removed MB 1.35 time faster than the EO process. Based on indirect determination of •OH, the •OH formation in the EO process was 2.4 ×10−13 M, which lower than that in the UV/EO process by 4 times. The second-order rate constant for MB oxidation by HO• (kHO•,MB) was 3.31 × 109 M−1s−1. The pseudo 1st-order decolorization kinetic (k’) was independent with voltages, but directly depended on CD and NaCl concentrations. Lower pH enhanced the k’ value. The specific energy consumption was in a range of 0.408 – 5.303 kWh/m3, depending on the k’ value. The energy consumption decreased with higher the k’ value, except for increasing CD. The Boron Doped Diamond (BDD) was more effective in the decolorization rate than dimensional active anode (DSA) by 1.6 times. Treatment of industrial dye wastewater by the UV/EO process eliminated color intensity (ADMI), COD, and BOD5 by 80 %, 91 %, and 9 %, respectively.