Electrochemical treatment of landfill leachate using different electrodes
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2021-11-29 |
| Journal | Research Society and Development |
| Authors | João Paulo Moreira Santos, Luiz Carlos Peppino Neto, Mateus Silveira Freitas, Geoffroy Roger Pointer Malpass, Deusmaque Carneiro Ferreira |
| Institutions | Universidade Federal do Triângulo Mineiro, Instituto Federal de Educação, Ciência e Tecnologia do Triângulo Mineiro |
| Analysis | Full AI Review Included |
Executive Summary
Section titled “Executive Summary”This study compares the electrochemical treatment of landfill leachate using Dimensionally Stable Anodes (DSA) and Boron Doped Diamond (BDD) electrodes, focusing on Total Organic Carbon (TOC) removal efficiency.
- Superior Performance of BDD: BDD demonstrated significantly superior performance, achieving a maximum TOC removal of 77.73% compared to the maximum 15.40% achieved by the DSA electrode.
- Optimal BDD Conditions: The optimized BDD process achieved 77.73% TOC removal at a current density of 82 mA cm-2, electrolysis time of 18.5 minutes, and 0.19 mol L-1 NaCl concentration.
- Electrode Mechanism Difference: The BDD electrode acts as a “non-active” anode, promoting the generation of highly reactive hydroxyl radicals (•OH) for complete mineralization, whereas the “active” DSA (Ti/Ru0.3Ti0.7O2) primarily leads to partial organic degradation.
- Discoloration: BDD treatment also achieved approximately 40% discoloration (Ultraviolet-Visible) of the leachate.
- Statistical Reliability: The optimization model for BDD showed excellent fit, yielding a coefficient of correlation (R2) of 0.9838.
- Leachate Complexity: The low efficiency of DSA and the formation of organochlorine byproducts (even with BDD) highlight the complexity and recalcitrance of the organic load in the leachate (initial TOC: 427 ppm).
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Initial TOC Concentration | 427 | ppm | Untreated Leachate Baseline |
| Initial pH | 7.8 | - | Untreated Leachate Baseline |
| DSA Anode Composition | Ti/Ru0.3Ti0.7O2 | - | Dimensionally Stable Anode (Active) |
| BDD Doping Level | 8000 | ppm B/C | Boron Doped Diamond Anode (Non-Active) |
| BDD Anode Area | 2.0 | cm2 | Geometric Area |
| DSA Anode Area | 1.68 | cm2 | Geometric Area |
| Maximum DSA TOC Removal | 15.40 | % | At 158 mA cm-2, 15 min, 0.2 mol L-1 NaCl |
| Maximum BDD TOC Removal | 77.73 | % | Highest measured/optimized result |
| Optimized BDD Current Density | 82 | mA cm-2 | Critical Optimization Point |
| Optimized BDD Electrolysis Time | 18.5 | minutes | Critical Optimization Point |
| Optimized BDD Electrolyte Conc. | 0.19 | mol L-1 | NaCl Electrolyte |
| BDD Discoloration Efficiency | ~40 | % | Ultraviolet-Visible |
| Statistical Model Fit (BDD) | 0.9838 | R2 | Coefficient of Correlation |
| Reactor Volume | 100 | mL | Single-compartment cell (20 mL leachate + 80 mL water) |
Key Methodologies
Section titled “Key Methodologies”The study utilized a quantitative, laboratory-scale approach based on statistical experimental design (Central Composite Rotational Design - CCRD).
- Electrode Configuration:
- Anodes: Commercial BDD (8000 ppm B/C) and commercial DSA (Ti/Ru0.3Ti0.7O2) were tested separately.
- Cathode: Platinum wire spiral was used as the auxiliary electrode in both setups.
- Electrolysis Setup: Experiments were conducted in a single-compartment electrochemical cell (100 mL capacity) under galvanostatic control using an Autolab PGSTAT 30 potentiostat/galvanostat.
- Experimental Design (CCRD): A 17-experiment matrix was generated to evaluate the influence of three independent variables:
- Current Density (X1): Ranging from 42 to 158 mA cm-2.
- Electrolysis Time (X2): Ranging from 1 to 30 minutes.
- Electrolyte Concentration (X3): Ranging from 0.084 to 0.32 mol L-1 NaCl.
- Leachate Preparation: Raw leachate samples were collected from a private landfill. Electrolyte solutions (NaCl) were prepared using deionized water.
- Analytical Methods:
- TOC Measurement: Total Organic Carbon decay was measured using a Shimadzu-4200 analyzer.
- Discoloration: Monitored via UV-Vis spectrophotometry (Perkin Elmer).
- Optimization: Response surface analysis was performed using Statistica 7.0 software to determine the critical conditions for maximum TOC removal efficiency.
Commercial Applications
Section titled “Commercial Applications”The successful application of BDD electrodes for high-efficiency TOC removal in complex, recalcitrant effluents positions this technology for several commercial and industrial uses:
- Landfill Leachate Treatment: Direct application for post-treatment or polishing of highly toxic, low-biodegradability leachate, enabling compliance with strict discharge limits.
- Industrial Wastewater Treatment: Processing effluents from industries (e.g., textile, pharmaceutical, chemical manufacturing) characterized by high Chemical Oxygen Demand (COD), color, and non-biodegradable organic compounds.
- Emerging Contaminant Destruction: Utilization in Electrochemical Advanced Oxidation Processes (EAOPs) specifically targeting the mineralization of persistent organic pollutants (POPs) and emerging contaminants (e.g., pharmaceuticals, endocrine disruptors) that resist conventional biological methods.
- Water Reuse Systems: Integration into tertiary treatment stages to ensure complete removal of trace organics before water is recycled or discharged into sensitive receiving waters.
- Modular Remediation Systems: Development of compact, modular electrochemical reactors based on BDD technology for decentralized environmental remediation efforts.
View Original Abstract
This article has as its objective a comparative study of the electrochemical treatment of slurry generated in landfills carried out with Dimensionally Stable Anodes (DSA) (Ti/Ru0.3Ti0.7O2) and Boron Doped Diamond (BDD). From the capacity planning and control (PCC), the central composite rotated design (DCCR) was obtained, whose independent variables in the electrolysis process were current density, time and electrolyte concentration. The removal of Total Organic Carbon (dependent variable) was 15.40% with current density 158 mA cm-², electrolysis time 15 minutes and 0.2 mol L-1 of the NaCl electrolyte using DSA. With the BDD, at the optimum point at 82 mA cm-², 18.5 minutes and 0.19 mol L-1, 77% removal of the organic load and discoloration of approximately 40% Ultraviolet-Visible.