Removal of microplastics by electrocoagulation

A systematic review of electrocoagulation technology applied for microplastics removal in aquatic environment

This study investigates the effect of voltage on the removal of polypropylene microplastics (PPMPs) from artificial wastewater via an electrocoagulation (EC) process using iron (Fe) electrodes. The effect of the voltage was investigated by conducting multiple continuous flow experiments at three different voltage values (10, 20, and 30 V). The findings demonstrated that the turbidity value increased gradually as the initial voltage increased, from 6.67 NTU at 10 V to 74.37 NTU at 30 V. In this EC process, in which Fe electrodes are utilized to remove the PPMPs, it is believed that 20 V provides optimal support. Kinetic studies showed that the process followed a first-order kinetic model with a kinetics rate constant (k) of 0.0143 min-1 and a coefficient of determination (R2) of 0.9702. The findings demonstrated that voltage is a significant parameter in the EC process employing Fe electrodes to remove PPMPs from wastewater.

The color and Chemical Oxygen Demand (COD) reduction in distillery industrial effluent (DIW) was investigated utilizing photo (UV), sono (US), electrocoagulation (EC), UV + US, UV + EC, US + EC, and US + UV + EC technologies. The empirical study demonstrated that the UV + US + EC process removed almost 100% of color and 95.63% of COD from DIW while consuming around 6.97 kWh m−3 of electrical energy at the current density of 0.175 A dm−2, COD of 3600 mg L−1, UV power of 32 W, US power of 100 W, electrode pairings of Fe/Fe, inter–electrode distance of 0.75 cm, pH of 7, and reaction time of 4 h, respectively. The values found were much greater than those produced using UV, US, EC, UV + US, UV + EC, and US + EC methods. The influence of various control variables such as treatment time (1–5 h), current density (0.075–2.0 A dm−2), COD (1800–6000 mg L−1), inter-electrode distance (0.75–3.0 cm), electrode pairings (Fe/Fe, Fe/Al, Al/Fe, Al/Al), UV (8–32 W), and US (20–100 W) on the color and COD reduction were investigated to determine the optimum operating conditions. It was observed that, an increase in treatment time, current density, UV and US power, decrease in the COD, and inter-electrode distance with Fe/Fe electrode combination improved the COD removal efficiency. The UV and US + EC processes' synergy index was investigated and reported. The results showed that, the US + UV + EC treatment combination was effective in treating industrial effluent and wastewater.

Tannery wastewater treatment using combined electrocoagulation and electro-Fenton processes

Integrated two-phase purification procedure for abatement of pollutants from sanitary landfill leachates

Objectives: In this research, the efficiency of the Electrocoagulation (EC) process with aluminum electrodes in the removal of Tetracycline (TC) from synthetic solutions was studied. Methods: This study experimentally was run consisting of a 1.5 L glass beaker and four electrodes which installed in parallel. In each of test, 1 L of wastewater add into the reactor, then effect of four parameters including the current density (100-400 A/m2), reaction time (10-60 min), initial concentration of TC (10-100 mg/L and the pH of wastewater (pH=3-11) on process performance were investigated. Results: The findings showed that the %removal decreased as initial TC concentration increased, the highest removal obtained at pH in the range (5- 7). The initial TC concentration of 10 mg/L was reduced to 0.127 mg/L with the removal efficiency of 98.73% at 400 A/m2 after 60 min EC. Conclusion: The results of this study indicate that EC process by aluminum electrode is an effective method for TC removal from wastewater.

Laundry wastewater is supposed to be one of the most important sources of surfactants and microplastics in the wastewater treatment plant. Consequently, the aim of the study was evaluating the performance and mechanism of the electro-hybrid ozonation–coagulation (E-HOC) process for the removal of surfactants and microplastics. In this study, the efficiency of the E-HOC process for surfactant and microplastic removal was examined at different current densities and ozone dosages. Under the optimal reaction conditions (current density 15 mA·cm−2, ozone dosage 66.2 mg·L−1), both the removal efficiency of surfactant and microplastic can reach higher than 90%. Furthermore, the mechanism of surfactant and microplastic removal was investigated by electron paramagnetic resonance (EPR) and Fourier transform infrared spectroscopy (FT-IR). The results showed that the E-HOC (carbon fiber cathode) system can produce more reactive oxygen species (ROS), which can significantly improve the removal of the contaminants. In addition, the shape, size and abundance of the microplastics were analyzed. It was found that the shape of the microplastics in laundry wastewater is mainly fiber. Microplastics less than 50 μm account for 46.9%, while only 12.4% are larger than 500 μm. The abundance of microplastics in laundry wastewater ranges between 440,000 and 1,080,000 items per 100 L. The analysis of microplastics by FT-IR showed that most of the microplastics in laundry wastewater were polyethylene, nylon and polyester. These results indicated that the E-HOC process can effectively remove surfactants and microplastics from laundry wastewater.

Comparison of COD removal from pharmaceutical wastewater by electrocoagulation, photoelectrocoagulation, peroxi-electrocoagulation and peroxi-photoelectrocoagulation processes

The aim of this study is to investigate the performance of advanced electrocoagulation (EC) process for the treatment of olive mill wastewater. In EC process, iron plates were used as electrodes, and peroxydisulfate (PS) and peroxymonosulfate (PMS) were added as oxidants. The effects of the initial pH value, current density, oxidant dose, and electrolysis time were optimized for pollutant removal from olive mill wastewater by EC-PS and EC-PMS processes. Control experiments showed that addition of oxidants to the conventional EC process increased the pollutant removal efficiency. Classical optimization method was used to determine optimum conditions, which were initial pH4, current density 40 mA/cm2 , oxidant dose 5g/L, and electrolysis time 30 min for both processes. Under these conditions, EC-PS and EC-PMS processes achieved 50.5% and 48.9% chemical oxygen demand (COD), 93.8% and 89.3% total phenol, 87.7% and 83% UV254 , and 74.5% and 64.1% total suspended solid removal efficiencies. Quenching experiments were performed to determine the dominant radical species participating in the processes. It was observed that hydroxyl and sulfate radicals were involved in both processes but hydroxyl radicals were more active. Specific energy consumption was calculated as 5.90 kWh/kg COD for EC process, 4.95 kWh/kg COD for EC-PS process, and 5.20 kWh/kg COD for EC-PMS process. The organic removal/sludge ratio of EC-PS process was found to be higher with 17.5g/L value. Although the application of EC-PS and EC-PMS processes alone is insufficient to meet the discharge limits, they have been found to be effective in olive mill wastewater treatment. PRACTITIONER POINTS: Peroxydisulfate (PS) and peroxymonosulfate (PMS)-based advanced electrocoagulation (EC) was used in olive mill wastewater treatment. 50.5% chemical oxygen demand (COD), 93.8% TP, 87.7% UV254 , and 74.5% TSS removals were achieved by EC-PS. 48.9% COD, 89.3% TP, 83% UV254 , and 64.1% TSS removals were obtained by EC-PMS. Hydroxyl and sulfate radicals were involved in both processes.

A hybrid electrocoagulation-biocomposite adsorption system for the decolourization of dye wastewater

Evaluation of flurbiprofen removal from aqueous solution by electrosynthesized ferrate(VI) ion and electrocoagulation process

In this study, the performance of the electrocoagulation (EC) process was evaluated for its capability to remove color, total organic carbon (TOC), chemical oxygen demand (COD) using aluminium electrodes. Response surface methodology based on Box-Behnken design was used to optimize different operating conditions of the processes. The interaction effects of four independent variables such as dye concentration, applied current density, electrolysis time, and pH on the percentage of COD, TOC, and color removal were investigated by the EC process. ANOVA analysis was made to examine the significance of input parameters and their interaction effect on responses. At the optimum operating conditions, 89% of color, 47% of TOC, and 76% of COD removal rate were achieved using the EC process. Different research works have been reported on the treatment of textile wastewater by the EC process. However, these researches vary regarding working conditions such as dye type, concentration, current density, pH, electrolysis time, and electrode type. Also, most literature focuses mainly on the performance of the technology. However, it is also important to investigate the economic aspect, removal mechanism, and mineralization study. Thus, economic analyses, mineralization, kinetic, sludge characterization studies of the technology were performed.

Performance evaluation of a biological landfill leachate treatment plant and effluent treatment by electrocoagulation

HF wastewater remediation by electrocoagulation process

The application of electrocoagulation process for treatment of the red mud dam wastewater from Bayer’s process