Container washing wastewater treatment by combined electrocoagulation–electrooxidation

Advancements in combined electrocoagulation processes for sustainable wastewater treatment: A comprehensive review of mechanisms, performance, and emerging applications

This review explores the potential and challenges of combining electrochemical, especially electrocoagulation (EC) process, with various - wastewater treatment methods such as membranes, chemical treatments, biological methods, and oxidation processes to enhance pollutant removal and reduce costs. It emphasizes the advantages of using electrochemical processes as a pretreatment step, including increased volume and improved quality of permeate water, mitigation of membrane fouling, and lower environmental impact. Pilot-scale studies are discussed to validate the effectiveness of combined EC processes, particularly for industrial wastewater. Factors such as electrode materials, coating materials, and the integration of a third process are discussed as potential avenues for improving the environmental sustainability and cost-effectiveness of the combined EC processes. This review also discusses factors for improvement and explores the EC process combined with Advanced Oxidation Processes (AOP). The conclusion highlights the need for combined EC processes, which include reducing electrode consumption, evaluating energy efficiency, and conducting pilot-scale investigations under continuous flow conditions. Furthermore, it emphasizes future research on electrode materials and technology commercialization. Overall, this review underscores the importance of combined EC processes in meeting the demand for clean water resources and emphasizes the need for further optimization and implementation in industrial applications.

Treatment and optimization of high-strength egg-wash wastewater effluent using electrocoagulation and electrooxidation methods

Egg-washing wastewater contains a high concentration of nutrition and organic matter since eggs are broken during the washing and cleaning processes. Moreover, the wastewater contains small amounts of detergents or sanitizing agents. These contaminants may pose environmental challenges when they are not properly managed or treated. The study scrutinizes the efficiency of electrocoagulation (EO) and electrooxidation (EO) approaches for egg-wash wastewater treatment. The response surface methodology was employed to optimize the operational parameters. The removal efficiencies of soluble chemical oxygen demand (sCOD 90%), ammonia (NH3-N 91%), nitrate (NO3--N 97%), nitrite (NO2--N 89.3%), total dissolved nitrogen (TDN 91%), and phosphate (90%) were measured under various treatment conditions. The optimum treatment conditions achieved in the combined EC + EO process were pH 6.0, current density 20 mA cm-2, and electrolysis time of 60 min, respectively. Degradation kinetics of the egg-wash pollutants showed a significant reduction in half-life (t1/2) with EO (after EC-Aluminum) at 15 min, 12 min, 17 min, and 15 min for sCOD, NO2--N. NO3--N, and TDN, respectively. Whereas the half-life of NH3-N (18 min) and phosphate (17 min) reduced significantly with the EO (after EC-iron). Al and Fe electrodes coupled with boron-doped diamond were found efficient for pollutant removal. Environmental implication. Egg-wash wastewater has a high protein content and contains nutrients that are essential for living organisms. While these compounds can be valuable for agricultural use by increasing soil phosphate concentration, they can also become an issue if the excess nutrients are not properly managed. The soil has a threshold limit for holding phosphate, and any excess amount may be transported through surface runoff or contaminate groundwater through leachate, potentially affecting aquatic ecosystems and water quality. This study explores the efficiency of electrocoagulation and electrooxidation methods in treating egg-wash wastewater. These methods aim to remove pollutants and reduce their environmental impact.

Modulating Cu valence state in Cu and graphene oxide composites for electrocatalytic tetracycline hydrochloride degradation

Cu and graphene oxide composites (Cu-GO) were designed by anchoring Cu+ via oxygen groups in GO based on the heavy co-relationships of copper (Cu) anode electrocatalytic activity with Cu valence state. With the consumption of oxygen groups under various pyrolysis temperatures, the Cu valence state changed from Cu ions (as CuCl2 and CuCl) to Cu oxide (CuO and Cu2O) and the final metallic Cu. In which the Cu+ in CuCl was more favorable for electrocatalytic oxidation than other Cu valence states. Due to the dramatic contribution of 1O2 and active chlorine, 100% degradation efficiency was achieved using tetracycline hydrochloride (TCH) as the target pollutant. Cu+ showed a selective preference for 1O2 and active chlorine triggering, rather than metallic Cu. Under the attack of 1O2 and active chlorine, the degradation intermediates of TCH were then provided by LC-MS results. The final results not only prove the feasibility of the Cu-GO/electrocatalysis system for pollution control but also shed light on the anode design via Cu valence state modulation.

Domestic greywater treatment using electrocoagulation-electrooxidation process: optimisation and experimental approaches

A synergistic combination of electrocoagulation-electrooxidation (EC-EO) process was used in the current study to treat domestic greywater. The EC process consisted of an aluminium (Al) anode and an iron (Fe) cathode, and the EO process consisted of titanium with platinum coating mesh (Ti/Pt) as an anode and stainless steel as a cathode. The effect of operative variables, namely current density, pH, EC time and EO time, on the removal of chemical oxygen demand (COD), colour, turbidity, and total organic carbon (TOC) was studied and optimised using Response Surface Methodology (RSM). The results showed that although the pH affected the removal of all studied pollutants, it had more effect on turbidity removal with a contribution of 88.44%, while the current density had the main dominant effect on colour removal with a contribution of 73.59%. It was also found that at optimal operation conditions for a current density of 2.6 A, an initial pH of 4.67, an EC time of 31.67 min, and an EO time of 93.28 min led to a COD, colour, turbidity, and TOC removal rates of 96.1%, 97.5%, 90.9%, and 98%, respectively, which were close to the predicted results. The average operating cost and energy consumption for the removal of COD, colour, turbidity, and TOC were 0.014 $/m3 and 0.01 kWh/kg, 0.083 $/m3 and 0.008 kWh/kg, 0.075 $/m3 and 0.062 kWh/kg, and 0.105 $/m3 and 0.079 kWh/kg, respectively.

Treatment of wastewater from the washing process of a municipal solid waste collection container by electrochemical treatment using different anode materials: a statistical optimization

An underground municipal solid waste (MSW) container should be washed periodically to prevent/reduce odor and leachate production. In this study, the treatment process of wastewater derived from the washing process of an MSW container was investigated using the electrochemical (EC) treatment process with different anode materials (Fe, TiO₂, and graphite). Response surface methodology (RSM) was used to evaluate the effect of process parameters such as initial pH, applied current, and reaction time on chemical oxygen demand (COD), Tannin/Lignin, and color removals. According to the results obtained from the RSM models, all process parameters were significant. The optimum process parameters in terms of COD removal were derived from the models for each anode material. Under the optimized conditions, the COD removals were determined to be 93.25%, 75.95%, and 98.46% for Fe-Fe, TiO₂-Fe, and graphite-Fe electrode pairs, respectively. The color and Tannin/Lignin removals were determined as 98.12% and 77.78% for the Fe-Fe, 92.76% and 98.45% for the TiO₂-Fe and 94.50% and 79.56% for the graphite-Fe electrode pair, respectively. The specific energy consumption (SEC) values were found as 46.95, 300.02, and 32.95 kWh/m³ for each electrode combination given above, respectively. In terms of both removal efficiencies and SEC, the most effective anode material was determined as graphite, followed by iron.

Combined electrocoagulation and electrooxidation treatment system for real effluents from the fishing industry

Fishing industries are characterized by high water consumption and a considerable content of organic matter and salt in their wastewater. In this work, a combined electrochemical process was studied at laboratory scale for the treatment of real wastewater from the processing of mackerel from an industrial facility located in the province of Buenos Aires that discharges to the sewer, which the plant is currently using and does not produce an effluent in discharge conditions. Taking advantage of the high conductivity of these effluents, in the electrocoagulation stage with aluminum anodes, it was possible to remove the coarsest fraction of suspended matter, achieving a Chemical Oxygen Demand (COD) removal of about 60%, at pH 7.5, showing a higher efficiency over the conventional treatment. Despite this superiority, the necessary removal was still not achieved; therefore, the wastewater treated by electrocoagulation was then subjected to electrooxidation, using a graphite anode and a titanium cathode, and with a first-order oxidation kinetics, achieving a final COD value lower than the discharge limit, after 7.5 min of processing at pH 6, obtaining an efficient treatment for removal of high concentrations dissolved organic matter and colloidal/suspended particles in this kind of effluent. All treatments were performed in batches. The removal of pollutants in the wastewater was verified by means of spectroscopic and voltammetric techniques; at the same time, these techniques, together with SEM-EDX analysis, proved the superiority of electrocoagulation over chemical coagulation. This study laid the groundwork for the design of modifications to the plant to achieve discharge parameters in accordance with current legislation.

Application of hybrid electrocoagulation and electrooxidation process for treatment of wastewater from the cotton textile industry

The hybrid electrocoagulation-electrooxidation (EC-EO) process was evaluated for its capability to remove color, total organic carbon (TOC), and chemical oxygen demand (COD). Aluminum (Al/Al) and iridium dioxide-coated onto titanium (IrO₂/Ti) electrodes were selected as anode/cathode for EC and EC-EO experiments, respectively. The box-Behnken statistical experimental design was used to optimize different operating conditions of the processes. The selected EC operating parameters are the concentrated dye concentration, applied current density, electrolysis time, and pH. The three chosen operating conditions for hybrid EC- EO processes are applied current density, pH, and electrolysis time. The results were evaluated based on the interaction effects of operating parameters of the treatment methods on the percentage of COD, TOC, and color removal. The EC process achieved 89% color and 76% COD removal rate at the optimum operating conditions. Likewise, the hybrid EC-EO process obtained 97% COD and color removal efficiency. FT-IR and ¹H and ¹³C NMR spectroscopy combined approach was employed to analyze the dye degradation extent. Both analysis results confirm the complete degradation of the organic contaminants into carbon dioxide and water. Thus, this study discloses that the treatment method using mesh IrO₂/Ti electrodes is a promising technology that could reach the discharge limit for industrial effluents. In addition, the optimum operating conditions are tested for real industrial wastewater effluents and show excellent performance in removing pollutants. Furthermore, the treatment method's mineralization study and economic analysis were performed and compared to other studies.

Transition towards Sustainable Carwash Wastewater Management: Trends and Enabling Technologies at Global Scale

Carwash wastewater (CWW) contains grease, oil, hydrocarbon residues, heavy metals, and surfactants, posing severe impacts to the environment and human health. Accordingly, various physical, chemical, and biological processes for CWW treatment have been demonstrated in recent research. In this study, a bibliometric approach was performed to comprehensively illustrate the recent progress, current direction, and future perspectives of CWW-related research. A keyword co-occurrence network was used to represent the results of the bibliometric analysis and to show the major pollutants in CWW effluents and the common systems for treating CWW via coagulation/flocculation, electrochemical, oxidation, membrane, adsorption, biological, and hybrid methods. An integrated anaerobic digestion/oxidation process has been reported to degrade CWW-associated pollutants and help develop an energy-efficient approach for waste management. The results demonstrated that the treatment of CWW has several benefits relevant to sustainable development, viz., good health and well-being, protection of life below water, bioenergy generation, and community awareness and acceptance towards wastewater reuse. Hence, these benefits could assist in meeting the environmental, economic, and social sustainable development goals (SDGs). These study outputs can encourage policymakers and stakeholders in implementing sensible regulations that control water usage and treatment in car sharing and personal vehicle services to either directly or indirectly adopt the agenda 2030 with its seventeen SDGs.

Suitability of electro-chemical reactor with copper electrode for sugar industry wastewater treatment: optimization of parameters, mechanism, kinetics and sludge analysis

The waste water generated from sugar industry contains a high degree of organic pollutant. Treating the sugar industry wastewater is thus crucial important for the environmental concern. The treated water can be reprocessed in different unit operation due to lack of fresh water. The purpose of this research work is to treat the sugarcane processing industry wastewater by electrochemical technology. The experiment was carried out with the copper electrode in batch mode. The input process parameters were optimized by using response surface methodology. At optimum condition at pH 6.79, current 4.97, electrode distance 1.41 and treatment ∼30 min, maximum 87.07% of chemical oxygen demand and 99.18% color removals was attained. A fairly high predicted value of regression coefficient for chemical oxygen demand (Pre-R 2) 0.81 and color (Pre-R 2) 0.851 and adjacent value for chemical oxygen demand (Adj-R 2) 0.46 and color (Adj-R 2) 0.589 was obtained between the experimental values and the calculate values by using a second-order regression model. The physicochemical characterizations of scum reveal less percentage of inorganic and it cane used as a micronutrient.

Clinoptilolite augmented electrocoagulation process for the reduction of high-strength ammonia and color from stabilized landfill leachate

The high-strength leachate produced from sanitary landfill is a serious issue around the world as it poses adverse effects on aquatic life and human health. Physio-chemical technology is one of the promising options as the leachate normally presents in stabilized form and not fully amendable by biological treatment. In this research, the effectiveness of natural zeolite (clinoptilolite) augmented electrocoagulation process (hybrid system) for removing high-strength ammonia (3,442 mg/L) and color (8,427 Pt-Co) from naturally saline (15 ppt) local landfill leachate was investigated. A batch mode laboratory-scale reactor with parallel-monopolar aluminum electrodes attached to a direct current (DC) electric power was used as an electrocoagulation reactor for performance enhancement purpose. Optimum operational conditions of 146 g/L zeolite dosage, 600 A/m² current density, 60 min treatment time, 200 rpm stirring speed, 35 min settling duration, and pH 9 were recorded with up to 70% and 88% removals of ammonia and color, respectively. The estimated overall operational cost was 26.22 $/m³ . The biodegradability of the leachate had improved from 0.05 to 0.27 in all post-treatment processes. The findings revealed the ability of the hybrid process as a viable option in eliminating concentrated ammonia and color in natural saline landfill leachate. PRACTITIONER POINTS: Clinoptilolite was augmented on the electrocoagulation process in saline and stabilized landfill leachate (15 ppt). The high strength NH₃ -N (3,442 mg/L) and color (8,427 Pt-Co) were 70% and 88% removed, respectively. The optimum conditions occurred at 140 g/L zeolite, 60 mA/cm² current density, 60 min, and final pH of 8.20. The biodegradability of the leachate improved from 0.05 to 0.27 after the treatment. This hybrid treatment was simple, faster, and did not require auxiliary electrolyte.

An overview on combined electrocoagulation-degradation processes for the effective treatment of water and wastewater

Electrocoagulation (EC) process is found as effective water and wastewater treatment method, as it can able to remove a variety of pollutants, treat various industrial wastewater, and able to handle fluctuations in pollutant quality and quantity. The performance of EC process can be improved significantly in combination with degradation processes. Different combinations of EC process with Fenton, electro-Fenton, photo-Fenton, photocatalysis, sonochemical treatment, ozonation, indirect electrochemical oxidation, anodic oxidation and sulfate radical based advanced oxidation process are found very effective for the treatment of water and wastewater. Enhanced performance of EC process in combination with degradation process was reported in most of the articles.

Soluble chemical oxygen demand removal from bypass wastewater using iron electrocoagulation

In-plant wastewater treatment strategies to handle bypass wastewater exceeding design capacity are insufficiently investigated in the scientific literature notwithstanding their importance in ensuring sustainable wastewater management. In this study, the effectiveness of iron electrocoagulation was investigated, for the first time, to enhance primary treatment capability in removing soluble chemical oxygen demand (sCOD) from bypass wastewater. In addition, the appropriate assumptions and experimental protocols for the application of adsorption isotherm models, widely used to describe the electrocoagulation process, were discussed in light of experimental results. Under neutral pH conditions, the bypass wastewater treatment was performed to test the effects of three preselected variables (electrolysis duration, current density, and temperature) on sCOD removal. Using a 15 mA/cm² current density, an average 52% sCOD removal efficiency was achieved after 15 min at 23 °C while approximately 40 min were needed to attain comparable removal efficiency at 8 °C. sCOD removals of 74% and 87% were achieved after 40 min treatment using a 22 mA/cm² current density at 8 °C and 23 °C, respectively. Experimental results and theory show that adsorption equilibrium was not reached in the electrocoagulation cell; consequently, variable-order-kinetic (VOK) models derived from Langmuir and Langmuir-Freundlich adsorption expressions were adapted to describe the process. These models were modified to account for the de facto estimation of ferric hydroxide (adsorbent) mass that accounts for the conversion of ferrous ion to particulate end products. The Langmuir-based VOK model was found to better describe sCOD removal under all the operating conditions tested and showed the sCOD removal mechanism to be consistent with chemisorption. This research shows the promising ability of iron electrocoagulation to achieve superior removal of sCOD as compared to established and emerging standalone bypass wastewater treatment technologies.

Treatment of canola-oil refinery effluent using electrochemical methods: A comparison between combined electrocoagulation + electrooxidation and electrochemical peroxidation methods

A comparative study of combined electrocoagulation (EC) + electrooxidation (EO) and electrochemical peroxidation (ECP) treatment processes were carried out to treat canola oil refinery (COR) wastewaters. The effect of applied current density and operation time in the removal of organic pollutants were investigated and discussed. Total chemical oxygen demand (TCOD), soluble chemical oxygen demand (sCOD), total organic carbon (TOC), dissolved organic carbon (DOC) and total suspended solids (TSS) were measured. Using only EC process was found to be significantly successful in removing suspended and colloidal pollutants and could remove more than 90% TCOD and 80% of TOC at current densities between 0.91 and 13.66 mA cm^-2. From the statistical model, the optimized conditions for TCOD at a current density of 7.61 mA cm^-2 and TOC at 7.99 mA cm^-2 under 40 min operation, validated to remove 93.45% and 94.5% respectively. However, the maximum removal of dissolved organic pollutants was relatively low in EC process and reported to be 75% for sCOD and 74% for DOC. Therefore, EC + EO process were run to increase the removal of sCOD and DOC to 99 and 95%, respectively. On the other hand, treatment using ECP process achieved a removal of sCOD and DOC between 77 and 86%. TSS were removed completely in both EC + EO and ECP processes. A statistical model was applied to compare the performance of two methods and found that the combined EC + EO process provided lightly better treatment compared to ECP method.