Periodic Reporting for period 1 - E-CORK (Advanced Electrochemical Treatments for Cork Washing Wastewater Remediation towards a Circular Economy)
Reporting period: 2022-01-28 to 2024-01-27
The difficulties in industrial wastewater treatment and management are exacerbating global water stress, where water regeneration and reuse are crucial. The role of producing industries and industrial wastewater treatment plants in seeking more cost-efficient and environmentally friendly technologies to address this issue is critical, presenting scientific, technological, environmental, and economic challenges. With a production of 162,000 tons per year, Portugal and Spain hold the largest global share of cork production, with cork stoppers for wine and champagne being the "star product." Approximately 90% of the cork stoppers used worldwide are produced in these two countries. The European Cork Federation has established mandatory practices to ensure the quality of natural stoppers, which involve several washing, bleaching, and disinfection steps. These procedures generate large volumes of wastewater, up to 195,000 m3/year, containing non-biodegradable organic matter, hydrogen peroxide used as a disinfectant and as a bleaching agent, and various dissolved salts, posing a serious risk to the environment and human health.
The E-CORK project is based on the premise that cork washing wastewaters can be effectively treated by electrochemical advanced oxidation processes. The main goal is to develop an optimized electrochemical treatment line for purifying and reusing cork washing wastewaters, taking advantage of the hydrogen peroxide present in the main effluent (from by-product to reactant). The project not only focuses on treatment performance but also considers its technical, economic, and environmental feasibility. Various advanced electrochemical processes are proposed, including electrocoagulation, electrochemical peroxidation, and photo-assisted electrochemical peroxidation (also known as electro-Fenton and photo-electro-Fenton with external hydrogen peroxide feeding). Through this approach and considering the possibility of reusing the regenerated wastewaters, the E-CORK project aims to transform the cork industry into a circular economy. It takes into account Portugal and Spain's inherent responsibility for promoting cleaner and more cost-efficient technologies that safeguard cork production and aquatic environments, establishing a close link with industrial needs.
During the first half of the project's life, electrochemical peroxidation under optimized conditions emerged as the most cost-efficient process for wastewaters with a high organic load. The treatment capitalizes on utilizing hydrogen peroxide, a by-product present in the effluent, as a reactant throughout the process, promoting a more sustainable approach to treatments within the cork processing industry.
The E-CORK project is based on the premise that cork washing wastewaters can be effectively treated by electrochemical advanced oxidation processes. The main goal is to develop an optimized electrochemical treatment line for purifying and reusing cork washing wastewaters, taking advantage of the hydrogen peroxide present in the main effluent (from by-product to reactant). The project not only focuses on treatment performance but also considers its technical, economic, and environmental feasibility. Various advanced electrochemical processes are proposed, including electrocoagulation, electrochemical peroxidation, and photo-assisted electrochemical peroxidation (also known as electro-Fenton and photo-electro-Fenton with external hydrogen peroxide feeding). Through this approach and considering the possibility of reusing the regenerated wastewaters, the E-CORK project aims to transform the cork industry into a circular economy. It takes into account Portugal and Spain's inherent responsibility for promoting cleaner and more cost-efficient technologies that safeguard cork production and aquatic environments, establishing a close link with industrial needs.
During the first half of the project's life, electrochemical peroxidation under optimized conditions emerged as the most cost-efficient process for wastewaters with a high organic load. The treatment capitalizes on utilizing hydrogen peroxide, a by-product present in the effluent, as a reactant throughout the process, promoting a more sustainable approach to treatments within the cork processing industry.
This summary pertains to the results obtained up to the halfway point of the project. The collaborating company, dedicated to the manufacture of cork stoppers, organized a visit to its facilities to understand the process and wastewater treatment performed there. Then, after a comprehensive characterization of the cork washing wastewaters (CWWs), electrocoagulation (EC) and electrochemical peroxidation (EP) processes were studied and optimized at the laboratory scale. Different effluents of CWWs were subjected to the processes in a batch cell, and the main operating conditions were studied: pH, electrolyte addition, current density, and different sacrificial anodes of Fe or Al. The evolution of the processes was monitored based on total organic carbon (TOC), dissolved organic carbon (DOC), COD, total nitrogen, turbidity, total solids, phenolic content, pH, conductivity, dissolved metals, short-chain organic acids, and hydrogen peroxide concentration. Due to the high organic load of the samples, the reusability for a new washing procedure was discarded at this stage. As relevant results, EC and EP using sacrificial iron anodes demonstrated to be efficient treatments for the remediation of cork washing wastewaters with different pollution loads (ranging from 3000-6000 mg/L COD). In general, EC was efficient enough to treat CWW with medium COD-DOC contents at the conditions tested but became ineffective in reaching the discharge limits for high-loaded CWW. Electrochemical peroxidation, with pH control near 3, emerged as the most cost-efficient process, achieving over 85% COD removal and ensuring final values below the discharge limits for the tested conditions. Additionally, a preliminary economic study was performed for electrocoagulation and electrochemical peroxidation of CWWs, leading to competitive operational costs for electrochemical peroxidation compared to conventional coagulation, due to the use of hydrogen peroxide, a by-product, as a reagent.
The progress achieved during this research is pending publication in an open-access journal, and part of the work has been presented at the international CIPOA-5: 5th Iberoamerican Conference on Advanced Oxidation Technologies, in Cusco (Peru), with an oral presentation entitled "Electrochemical treatments for cork bleaching wastewaters". Additionally, a website for the E-CORK project has been created to disseminate and provide updates on related achievements.
The progress achieved during this research is pending publication in an open-access journal, and part of the work has been presented at the international CIPOA-5: 5th Iberoamerican Conference on Advanced Oxidation Technologies, in Cusco (Peru), with an oral presentation entitled "Electrochemical treatments for cork bleaching wastewaters". Additionally, a website for the E-CORK project has been created to disseminate and provide updates on related achievements.
For the first time, the application of advanced electrochemical treatments to cork washing wastewaters remediation has been studied, utilizing hydrogen peroxide, a by-product of the washing procedure, as a resource for the treatments. The primary objective was to make the cork industry more sustainable. All the referenced works dealing with electrochemical treatments emphasize the importance of directing electrochemical advanced oxidation processes towards real industrial wastewater, opening the door for new studies in this field. The comprehensive approach proposed in E-CORK constitutes a complete strategy that could be utilized by researchers and industries to treat wastewaters of different origins. Furthermore, the development of the technology proposed in E-CORK for treating an actual problem, in close collaboration with the industrial cork stopper manufacturer, represents a significant technological and industrial advancement. This could be further explored with the possibility of seeking new joint projects to transfer knowledge from research results. Lastly, the improvement in the quality of the treated water, along with the use of a washing by-product as a resource to regenerate the wastewater within the philosophy of the circular economy, has managed to reduce water and chemical compound consumption compared to established procedures in cork industries. This contributes positively to society from both environmental and public health perspectives.