A comprehensive review on green perspectives of electrocoagulation integrated with advanced processes for effective pollutants removal from water environment.

The rapidly expanding global energy demand is forcing a release of regulated pollutants into water that is threatening human health. Among various wastewater remediating processes, electrocoagulation (EC) has scored a monumental success over conventional processes because it combines coagulation, sedimentation, floatation and electrochemical oxidation processes that can effectively decimate numerous stubborn pollutants. The EC processes have gained some attention through various academic and industrial publications, however critical evaluation of EC processes, choices of EC processes for various pollutants, process parameters, mechanisms, commercial EC technologies and performance enhancement via other degradation processes (DPs) integration have not been comprehensively covered to date. Therefore, the major objective of this paper is to provide a comprehensive review of 20 years of literature covering EC fundamentals, key process factors for a reactor design, process implementation, current challenges and performance enhancement by coupling EC with pivotal pollutant DPs including, electro/photo-Fenton (E/P-F), photocatalysis, sono-chemical treatment, ozonation, indirect electrochemical/advanced oxidation (AO), and biosorption that have substantially reduced metals, pathogens, toxic compound BOD, COD, colors in wastewater. The results suggest that the optimum treatment time, current density, pulse frequency, shaking speed and spaced electrode improve the pollutants removal efficiency. An elegant process design can prevent electrode passivation which is a critical limitation of EC technology. EC coupling (up or downstream) with other DPs has resulted in the removal of organic pollutants and heavy metals with a 20% improved efficiency by EC-EF, removal of 85.5% suspended solid, 76.2% turbidity, 88.9% BOD, 79.7% COD and 93% color by EC-electroflotation, 100% decolorization by EC-electrochemical-AO, reduction of 78% COD, 81% BOD, 97% color by EC-ozonation and removal of 94% ammonia, 94% BOD, 95% turbidity, >98% phosphorus by aerated EC and peroxicoagulation. The major wastewater purification achievements, future potential and challenges are described to model the future EC integrated systems.

Removal of nutrients and other emerging inorganic contaminants from water and wastewater by electrocoagulation process.

The continual discharge of emerging inorganic pollutants into natural aquatic systems and their negative effects on the environment have motivated the researchers to explore and develop clean and efficient water treatment strategies. Electrocoagulation (EC) is a rapid and promising pollutant removal approach that does not require any chemical additives or complicated process management. Therefore, inorganic pollutant treatment via the EC process is considered one of the most feasible processes. The potential developments of EC process may make the process a wise choice for water treatment in the future. Thus, the present study mainly focuses on the use of EC technology to remove nutrients and other emerging inorganic pollutants from water medium. The operating factors that influence EC process efficiency are explained. The major advancement of the EC technique as well as field-implemented units are also discussed. Overall, this study mainly focuses on emerging issues, present advancements, and techno-economic considerations in EC process.

Studies on electrode combination for COD removal from domestic wastewater using electrocoagulation.

Electrocoagulation is an electrochemical method that uses sacrificial electrodes to remediate wastewater. The combination of electrodes for the treatment of domestic wastewater is the factor that influences the removal efficiency of COD (Chemical Oxygen Demand) by using the electrocoagulation process. Aluminum and Iron electrodes are combined as anode-cathode and cathode-anode in Al-Al, Fe-Fe, Al-Fe, and Fe-Al. Different factors are considered to evaluate the removal efficiency of COD like; pH (3-9), reaction time (15-60 min), and current density (9.23-45 A/m2). Based on this influencing factor Al-Al and Fe-Fe can remove COD up to 87.5 % and 90 % respectively. Similarly, 87.5 % and 88.89 % of COD were removed, when aluminum and iron were combined as Al-Fe and Fe-Al respectively. In addition, the effects of different operating parameters were discussed on the removal percentage of COD. This indicated that the combination of electrode influence the removal efficiency of COD using the electrocoagulation process under different operating parameters.

Wastewater treatment using a natural coagulant (Moringa oleifera seeds): optimization through response surface methodology.

The high expense of chemical coagulant-treated water forces most people in rural regions to rely on easily available sources, which are usually of poor quality, and expose them to waterborne infections. According to this statement, the purpose of this study was to confirm the efficiency of extracting powder Moringa oleifera seeds, which are widely available in rural regions. The experiment was done based on a random design load of 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 g/500 ml of powder extracted from Moringa seeds. Chemical oxygen demand (COD), color, and turbidity were determined for both acidic and basic characteristics of wastewater. The optimum dosage of Moringa oleifera was 0.4 g/500 ml in both characteristics of wastewater in the case of color and turbidity. Moringa oleifera maximum reduction in turbidity, color, and COD in acidic wastewater was 98 %, 90.76 %, and 65.8 % respectively; while, the maximum reduction of turbidity, color, and COD in basic wastewater were 99.5 %, 97.7 %, and 65.82 % respectively. The study was demonstrated that, the application of RSM for seeking optimum conditions in the coagulation process for the treatment of wastewater. Moringa seed powder works best with a 7-9 pH range. The study also investigated that, best adsorption equilibrium was observed when using 0.1 g of Moringa oleifera seed powder. All the results showed that Moringa oleifera seeds were very effective for the removal of impurities.