Anodic Oxidation of Industrial Winery Wastewater Using Different Anodes
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-01-04 |
| Journal | Water |
| Authors | Yeney Lauzurique, L. Carolina Espinoza, CĂ©sar Huiliñir, VerĂłnica GarcĂa, Ricardo Salazar |
| Institutions | University of Chile, Universidad de Santiago de Chile |
| Citations | 14 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis study successfully demonstrates the high efficiency of Anodic Oxidation (AO) using a Boron-Doped Diamond (BDD) electrode for treating real industrial winery wastewater without the addition of supporting electrolytes or pH adjustment.
- Superior Mineralization: The BDD anode achieved 85% Total Organic Carbon (TOC) mineralization, significantly outperforming the Mixed Metal Oxide (MMO) anodes (MMO-Cl2: 1.70%; MMO-O2: 3.34%).
- Mechanism Confirmation: The high performance of BDD is attributed to its non-active nature, which favors the generation of highly reactive physisorbed hydroxyl radicals (*OH), leading to complete mineralization rather than intermediate formation.
- Real-World Applicability: The process was conducted on real Chilean winery wastewater (initial TOC 1349 mg/L, pH 4.28) at a constant current density of 30 mA/cm2, simplifying the treatment train by eliminating the need for chemical additives.
- Pollutant Removal: BDD achieved 85% decay in maximum absorbance (254 nm, indicating polyphenol degradation) and 59% reduction in turbidity.
- Inorganic Ion Role: The high concentration of inherent inorganic ions (Chloride, Sulfate, Phosphate) contributed to the formation of secondary oxidants (active chlorine species, persulfate, perphosphate), enhancing the overall oxidative power of the system.
- MMO Limitation: MMO electrodes (active anodes) failed to mineralize persistent carboxylic acids (acetic and propionic acid), which accumulated or increased in concentration during electrolysis.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Wastewater Source | Chilean Winery Industry | N/A | Composite sample (Oct-Nov 2018) |
| Initial TOC | 1349 ± 25.24 | mg/L | Total Organic Carbon |
| Initial sCOD | 4140 ± 28.28 | mg/L | Soluble Chemical Oxygen Demand |
| Initial pH | 4.28 ± 0.16 | N/A | Natural pH (no adjustment) |
| Initial Conductivity | 2.60 ± 0.04 | mS | At 25.80 °C |
| Initial Chloride (Cl-) | 364 ± 1.73 | mg/L | High concentration, key for secondary oxidants |
| Anode Type (BDD) | Boron-Doped Diamond | N/A | Non-active anode, 500 ppm Boron doping |
| Anode Type (MMO-Cl2) | Ti/Ru0.3Ti0.7O2 | N/A | Mixed Metal Oxide (Active anode) |
| Anode Type (MMO-O2) | Ti/Ir0.45Ta0.55O2 | N/A | Mixed Metal Oxide (Active anode) |
| Electrode Area | 5 | cm2 | Geometric area of anode and cathode |
| Current Density (j) | 30 | mA/cm2 | Applied constant current density |
| Electrolysis Duration | 540 | min | Total reaction time |
| TOC Removal (BDD) | 85 | % | Mineralization efficiency |
| TOC Removal (MMO Avg.) | 2.52 | % | Average for MMO-Cl2 and MMO-O2 |
| Absorbance Decay (BDD) | 85 | % | Measured at 254 nm |
| Turbidity Reduction (BDD) | 5.03 | NTU | Final turbidity value (59% reduction) |
| Final pH (BDD) | 8.15 ± 0.10 | N/A | Significant increase due to *OH generation |
Key Methodologies
Section titled âKey MethodologiesâThe electrochemical advanced oxidation process (AO) was performed in an undivided 0.10 L open cell under galvanostatic control without adding supporting electrolytes.
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Wastewater Preparation:
- Winery wastewater samples were collected over eight months (April-November 2018) to characterize seasonality.
- A composite sample was created from October and November collections.
- The sample was centrifuged to reduce suspended solids (Turbidity reduced by 96% from 321 NTU to 12.3 NTU).
-
Electrode Preparation:
- Three anodes were tested: BDD (2.75 ”m thick, 500 ppm B), MMO-Cl2 (Ti/Ru0.3Ti0.7O2), and MMO-O2 (Ti/Ir0.45Ta0.55O2).
- The cathode was stainless steel (AISI 304).
- Electrodes were pre-polarized in 0.50 M H2SO4 solution at 50 mA/cm2 for 40 min to remove surface impurities.
-
Electrolysis Conditions:
- Cell: Undivided 0.10 L open cell with vigorous stirring (to ensure mass transfer).
- Temperature: Room temperature (25 °C).
- Current Density: Constant 30 mA/cm2.
- Electrolyte: None added; natural conductivity (2.60 mS) was utilized.
- Duration: 540 min.
-
Analytical Monitoring:
- Mineralization was tracked via Total Organic Carbon (TOC) decay (Shimadzu TOC-L analyzer).
- Degradation of specific compounds (polyphenols) was monitored by absorbance decay at 254 nm.
- Carboxylic acids (oxamic, acetic, propionic) were quantified using ion exclusion chromatography (Shimadzu LC-20AD UFLC).
- Inorganic ions (Cl-, SO42-, NO3-, PO43-, ClO-, ClO3-) were monitored using ion chromatography.
Commercial Applications
Section titled âCommercial ApplicationsâThe findings support the implementation of high-efficiency electrochemical treatment systems, particularly those utilizing BDD anodes, in industries generating complex organic wastewater.
- Winery and Food Processing Wastewater Treatment: Direct application for treating high-load, seasonal effluents common in the wine, beer, and fruit processing industries, achieving high mineralization (85% TOC removal) without costly chemical pre-treatment.
- Advanced Oxidation Processes (AOPs): Validates BDD as the preferred anode material for industrial EAOPs targeting recalcitrant organic compounds (e.g., polyphenols, pesticides, fertilizers) that resist conventional biological treatment.
- Effluent Polishing and Water Reuse: The ability to significantly reduce TOC, turbidity, and absorbance makes this technology suitable for tertiary treatment, enabling compliance with stringent discharge limits or facilitating water reuse within industrial facilities.
- Simplified Treatment Trains: Eliminates the need for pH adjustment and external electrolyte addition, reducing operational complexity and chemical costs associated with traditional AO methods.
- Pharmaceutical and Chemical Wastewater: The demonstrated effectiveness of BDD in mineralizing persistent organic acids (like oxamic acid, an intermediate) suggests utility in treating complex chemical or pharmaceutical wastewater streams.
View Original Abstract
Winery wastewater represents the largest waste stream in the wine industry. This deals with the mineralization of the organic matter present in winery wastewater using anodic oxidation and two types of anodesânamely, a boron-doped diamond electrode (BDD) and two mixed metal oxides (MMO), one with the nominal composition Ti/Ru0.3Ti0.7O2 and the other with Ti/Ir0.45Ta0.55O2. To conduct the study, the variability of different quality parameters for winery wastewater from the Chilean industry was measured during eight months. A composite sample was treated using anodic oxidation without the addition of supporting electrolyte, and the experiments were conducted at the natural pH of the industrial wastewater. The results show that this effluent has a high content of organic matter (up to 3025 ± 19 mg/L of total organic carbon (TOC)), which depends on the time of the year and the level of wine production. With MMO electrodes, TOC decreased by 2.52% on average after 540 min, which may be attributed to the presence of intermediate species that could not be mineralized. However, when using a BDD electrode, 85% mineralization was achieved due to the higher generation of hydroxyl radicals. The electrolyzed sample contained oxamic, acetic, and propionic acid as well as different ions such as sulfate, chloride, nitrate, and phosphate. These ions can contribute to the formation of different species such as active species of chlorine, persulfate, and perphosphate, which can improve the oxidative power of the system.
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
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