Electrochemical Oxidation of Landfill Leachate after Biological Treatment by Electro-Fenton System with Corroding Electrode of Iron

At a Glance

Metadata	Details
Publication Date	2022-06-24
Journal	International Journal of Environmental Research and Public Health
Authors	Juan Tang, Shuo Yao, Fei Xiao, Jianxin Xia, Xing Xuan
Institutions	Minzu University of China, Energy Foundation
Citations	7
Analysis	Full AI Review Included

Technical Documentation & Analysis: BDD for Advanced Electrochemical Oxidation

This document analyzes the research paper “Electrochemical Oxidation of Landfill Leachate after Biological Treatment by Electro-Fenton System with Corroding Electrode of Iron” and outlines how 6CCVD’s advanced MPCVD diamond materials and customization capabilities can support and extend this critical environmental technology.

Executive Summary

The research successfully demonstrated the high efficacy of a novel electrochemical system utilizing a Boron-Doped Diamond (BDD) anode for advanced landfill leachate treatment. Key findings and material implications are summarized below:

High Performance Oxidation: The BDD-Fe_c-CF system achieved exceptional removal efficiencies under optimal conditions: 99.8% for Ammonia Nitrogen (NH₃-N) and 81.3% for Chemical Oxygen Demand (COD).
Material Criticality: The BDD anode’s high stability, wide potential window, and extremely high oxygen evolution potential were essential for generating the powerful hydroxyl radicals (·OH) required for refractory organic pollutant degradation.
System Versatility: The system operates effectively across a wide pH range (3-11), utilizing electrochemical oxidation and Fenton chemistry under acidic conditions, and leveraging coagulation (Fe(OH)₃) and Fe(VI) oxidation under alkaline conditions.
Optimization Methodology: Response Surface Methodology (RSM) with Box-Behnken Design (BBD) was successfully applied to optimize key variables (current density, electrolytic time, and pH).
Refractory Compound Destruction: GC-MS analysis confirmed the destructive power of the system, reducing the number of detectable organic compounds from 56 types to only 16 types after treatment.
Commercial Potential: The BDD-based system demonstrates great potential for the advanced, cost-effective treatment of highly contaminated industrial and municipal effluents.

Technical Specifications

The following hard data points were extracted from the research, highlighting the operational parameters and performance metrics achieved using the BDD-Fe_c-CF system.

Parameter	Value	Unit	Context
Anode Material	Boron-Doped Diamond (BDD)	N/A	Key electrochemical component
BDD Anode Dimensions	20 x 20 x 1	mm	Used in the BDD-Fe_c-CF system
Optimal Current Density (X₁)	25	mA·cm⁻²	Optimized operating condition
Optimal Electrolytic Time (X₂)	9	h	Optimized operating condition
Optimal pH (X₃)	11	N/A	Optimized operating condition (Alkaline)
Predicted COD Removal (Y₁)	81.3	%	Under optimal conditions
Predicted NH₃-N Removal (Y₂)	99.8	%	Under optimal conditions
Initial COD Concentration (Avg)	2464	mg·L⁻¹	Biologically treated leachate influent
Initial NH₃-N Concentration (Avg)	154.4	mg·L⁻¹	Biologically treated leachate influent
Operating Temperature	20	°C	Room temperature
Initial Leachate pH (Avg)	7.22	N/A	Biologically treated leachate influent

Key Methodologies

The electrochemical oxidation was performed using a novel three-component system optimized via statistical design.

System Configuration: A one-compartment cell (400 mL beaker) was constructed using a BDD anode and a Carbon Felt (CF) cathode, separated by a corroding iron electrode (Fe_c) without an electronic charge (BDD-Fe_c-CF).
Electrode Preparation:
- The BDD anode measured 20 mm x 20 mm x 1 mm (4 cm² surface area).
- The CF cathode was pre-treated by soaking in 4.5 M NaOH and 5 M HCl.
- The Fe_c electrode was sanded and soaked in 0.5 M HCl.
Electrolysis Conditions: The process was run under galvanostatic conditions (constant direct current) at room temperature (20 °C).
Optimization Design: Response Surface Methodology (RSM) using a three-factor, three-level Box-Behnken Design (BBD) was employed.
- Independent Variables: Current density (15 to 25 mA·cm⁻²), Electrolytic time (3 to 9 h), and pH (3 to 11).
- Response Variables: COD removal efficiency (Y₁) and NH₃-N removal efficiency (Y₂).
Analytical Characterization:
- COD and NH₃-N concentrations were measured using standard titrimetric and colorimetric methods, respectively.
- Organic compound identification before and after treatment was performed using Gas Chromatography-Mass Spectrometry (GC-MS).

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-quality BDD materials and custom engineering required to replicate, scale, and advance this electrochemical oxidation research for industrial wastewater applications.

Applicable Materials

The success of the BDD-Fe_c-CF system relies entirely on the quality and doping level of the BDD anode to ensure high efficiency in generating powerful oxidants (·OH).

Research Requirement	6CCVD Solution	Material Specification
High Oxidation Potential	Heavy Boron-Doped Diamond (BDD)	MPCVD BDD films optimized for electrochemical applications, ensuring maximum charge transfer and radical generation.
Mechanical Stability	SCD or PCD Substrates	BDD films grown on high-quality Single Crystal Diamond (SCD) or Polycrystalline Diamond (PCD) substrates for superior mechanical and chemical inertness in harsh environments (wide pH range).
Electrode Size	Custom BDD Plates	While the paper used 20 mm x 20 mm, 6CCVD provides custom BDD plates/wafers up to 125mm in diameter (PCD) for pilot and industrial scale-up.

Customization Potential

Scaling this BDD-Fe_c-CF system from the lab (4 cm² electrodes) to industrial application requires precise material control and integration capabilities, which 6CCVD provides:

Custom Dimensions and Thickness: 6CCVD offers BDD plates in custom dimensions far exceeding the 20 mm x 20 mm used in the study. We provide precise thickness control for both the BDD film (0.1 µm to 500 µm) and the underlying substrate (up to 10 mm).
Advanced Metalization Services: For robust, long-term electrical contact necessary for industrial reactors, 6CCVD provides in-house metalization services. We can deposit custom contact layers (e.g., Ti/Pt/Au, W, Cu) tailored for high current density applications, ensuring low resistance and high durability.
Surface Finish Optimization: While the paper focused on bulk oxidation, surface quality is crucial for maximizing active sites. 6CCVD offers ultra-smooth polishing (Ra < 1nm for SCD, Ra < 5nm for inch-size PCD) to meet specific surface requirements for enhanced electrochemical performance.

Engineering Support

6CCVD’s in-house PhD team specializes in the material science of diamond for electrochemical and advanced oxidation processes (AOPs). We offer comprehensive engineering support for projects involving:

Electrochemical Wastewater Treatment: Assisting researchers and engineers in selecting the optimal BDD doping concentration and substrate type for specific effluent compositions (e.g., high chloride, high COD/NH₃-N).
Reactor Design and Scale-Up: Providing material specifications necessary for transitioning from laboratory-scale experiments to pilot-scale BDD electrochemical reactors.
Novel Electrode Integration: Consulting on the integration of BDD anodes into complex systems, such as the BDD-Fe_c-CF configuration, ensuring material compatibility and maximizing system efficiency.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Electrochemical oxidation of landfill leachate after biological treatment by a novel electrochemical system, which was constructed by introducing a corroding electrode of iron (Fec) between a boron-doped diamond (BDD) anode and carbon felt (CF) cathode (named as BDD-Fec-CF), was investigated in the present study. Response surface methodology (RSM) with Box-Behnken (BBD) statistical experiment design was applied to optimize the experimental conditions. Effects of variables including current density, electrolytic time and pH on chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) removal efficiency were analyzed. Results showed that electrolytic time was more important than current density and pH for both COD and NH3-N degradation. Based on analysis of variance (ANOVA) under the optimum conditions (current density of 25 mA·cm−2, electrolytic time of 9 h and pH of 11), the removal efficiencies for COD and NH3-N were 81.3% and 99.8%, respectively. In the BDD-Fec-CF system, organic pollutants were oxidized by electrochemical and Fenton oxidation under acidic conditions. Under alkaline conditions, coagulation by Fe(OH)3 and oxidation by Fe(VI) have great contribution on organic compounds degradation. What is more, species of organic compounds before and after electrochemical treatment were analyzed by GC-MS, with 56 kinds components detected before treatment and only 16 kinds left after treatment. These results demonstrated that electrochemical oxidation by the BDD-Fec-CF system has great potential for the advanced treatment of landfill leachate.

Tech Support

Original Source

DOI: https://doi.org/10.3390/ijerph19137745

References

2017 - Review on landfill leachate treatment by electrochemical oxidation: Drawbacks, challenges and future scope [Crossref]
2019 - Solid waste management: Scope and the challenge of sustainability [Crossref]
2020 - Electro-catalytic ozonation for improving the biodegradability of mature landfill leachate [Crossref]
2020 - A review of the application of adsorbents for landfill leachate treatment: Focus on magnetic adsorption [Crossref]
2015 - Assessment of various tropical municipal landfill leachate characteristics and treatment opportunities
2019 - Improved landfill leachate quality using ozone, UV solar radiation, hydrogen peroxide, persulfate and adsorption processes [Crossref]
2020 - Enhancing microalgae growth and landfill leachate treatment through ozonization [Crossref]
2019 - Application of the Fenton and Fenton-like processes in the landfill leachate tertiary treatment [Crossref]
2020 - A new insight into highly contaminated landfill leachate treatment using Kefir grains pre-treatment combined with Ag-doped TiO2 photocatalytic process [Crossref]
2015 - Degradation of the antibiotic oxacillin in water by anodic oxidation with Ti/IrO2 anodes: Evaluation of degradation routes, organic by-products and effects of water matrix components [Crossref]