Chemical and Electrochemical Combined Processes to Treat Sanitary Landfill Leachates

At a Glance

Metadata	Details
Publication Date	2015-01-01
Journal	Portugaliae electrochimica acta
Authors	Annabel Fernandes, N Afonso, João Coelho, Maria José Pacheco, Lurdes Ciríaco
Institutions	University of Beira Interior
Citations	6
Analysis	Full AI Review Included

Technical Analysis and Documentation: High-Performance BDD Anodes for Advanced Leachate Treatment

Executive Summary

This documentation analyzes the application of Boron-Doped Diamond (BDD) anodes in a combined Chemical Coagulation (CC) and Electrochemical Oxidation (EO) process for treating complex sanitary landfill leachates. The findings confirm BDD’s superior efficacy in mineralizing refractory organic pollutants.

Core Application: Highly effective treatment of sanitary landfill leachate using BDD electrochemical oxidation following lime-based chemical coagulation.
Material Validation: BDD anodes demonstrated high stability and efficiency in degrading complex, refractory organic compounds (high molecular weight humic acids).
Performance Metrics: The combined CC+EO process achieved high Chemical Oxygen Demand (COD) removals and complete removal of Total Kjeldahl Nitrogen (TKN) and Total Ammonia Nitrogen (TAN).
Optimal Conditions: Highest current efficiency was achieved during the EO step at an applied current intensity of 0.4 A, following CC pre-treatment (20 g L^-1 lime, 2.5 h).
Biodegradability Enhancement: The CC pre-treatment significantly increased the biodegradability index (BOD₅/COD ratio) of the leachate, making subsequent EO more efficient.
6CCVD Value Proposition: 6CCVD specializes in manufacturing high-quality, custom-dimensioned BDD wafers and plates, ideal for scaling up this high-efficiency wastewater treatment technology.

Technical Specifications

The following table summarizes the critical operational parameters and performance metrics related to the BDD electrochemical oxidation (EO) step and the initial leachate characteristics.

Parameter	Value	Unit	Context
Anode Material	Boron-Doped Diamond (BDD)	N/A	Used for Electrochemical Oxidation (EO)
Cathode Material	Stainless Steel	N/A	Counter electrode
Electrode Area	10	cm²	Area of both BDD anode and cathode
Applied Current Intensity (Optimal)	0.4	A	Yielded the highest current efficiency
Applied Current Intensity (Tested)	0.4 and 0.6	A	Range tested for EO assays
EO Duration	6	h	Duration of the electrochemical treatment
Initial COD (Leachate)	4.0 ± 0.3	g L^-1	Initial concentration before treatment
Initial BOD₅/COD Ratio	0.31 ± 0.04	N/A	Low initial biodegradability
Final BOD₅/COD Ratio (CC, 25 g L^-1)	0.38	N/A	Increased biodegradability after CC
TKN/TAN Removal (Combined CC+EO)	~100	%	Complete removal achieved
Final Conductivity (EO, 0.4 A, 20 g L^-1)	6.9 ± 0.5	mS cm^-1	Significant drop observed during EO

Key Methodologies

The electrochemical oxidation (EO) assays utilized a BDD anode in a batch reactor setup following optimized chemical coagulation (CC) pre-treatment.

Pre-treatment Optimization (CC): Chemical coagulation was performed using lime (Ca(OH)₂). Optimal conditions were determined to be 20 or 25 g L^-1 lime concentration, 100 rpm stirring speed, and 2.5 hours duration.
Sample Preparation: Leachate samples were pre-treated, centrifuged at 5000 rpm for 5 minutes, and 200 mL of the supernatant liquid was collected for EO.
Electrochemical Cell Setup: Experiments were conducted in batch mode at room temperature (22-25 °C) using a BDD anode and a stainless steel cathode.
Electrode Dimensions: Both electrodes had an area of 10 cm².
Power Supply: A DC power supply (GW, Lab DC, model GPS-3030D) was used to maintain constant current intensity.
Current Application: Two applied current intensities were tested: 0.4 A and 0.6 A.
Monitoring: Degradation was tracked by measuring COD, DOC, TN, TKN, and TAN, confirming the BDD anode’s ability to mineralize complex organic and nitrogenous species.

6CCVD Solutions & Capabilities

This research validates the critical role of high-quality Boron-Doped Diamond (BDD) in advanced electrochemical wastewater treatment. 6CCVD is uniquely positioned to supply the necessary BDD materials and custom electrode configurations required to replicate, scale, and optimize this technology.

Applicable Materials

To replicate or extend this research, high-performance BDD films are essential. 6CCVD recommends:

Heavy Boron-Doped PCD (Polycrystalline Diamond): Ideal for large-scale electrochemical applications like leachate treatment. Our MPCVD process ensures high, uniform boron doping necessary for maximizing hydroxyl radical generation and achieving high current efficiency (as demonstrated at 0.4 A).
- Thickness: Available from 0.1 µm up to 500 µm, allowing optimization for cost and longevity.
- Dimensions: We offer custom plates and wafers up to 125 mm in diameter, significantly exceeding the 10 cm² area used in the study, enabling direct scale-up.

Customization Potential

The study utilized a simple 10 cm² electrode. For industrial implementation or advanced research, 6CCVD offers comprehensive customization services:

Requirement from Research/Scale-Up	6CCVD Customization Capability	Technical Advantage
Electrode Size	Custom plates/wafers up to 125 mm (PCD/BDD).	Enables pilot-scale and industrial reactor design.
Electrode Geometry	Precision laser cutting and shaping services.	Allows creation of complex geometries (e.g., mesh, tubes) for optimized mass transfer.
Electrical Contact	Internal metalization services (Ti, Pt, Au, Pd, W, Cu).	Ensures robust, low-resistance electrical contact necessary for high-current density operation in corrosive environments.
Surface Finish	Polishing services (Ra < 5 nm for inch-size PCD).	Improves flow dynamics and reduces fouling potential in high-solids leachate applications.

Engineering Support

The successful implementation of BDD technology relies on precise material selection and integration.

Material Selection for Environmental Applications: 6CCVD’s in-house PhD team specializes in optimizing BDD doping levels and film morphology to maximize electrochemical efficiency (current efficiency and COD removal) for complex environmental projects, such as landfill leachate remediation and industrial wastewater treatment.
Electrode Integration Consultation: We provide technical support for integrating BDD films onto various substrates and designing the optimal metalization scheme for long-term stability under high current loads (0.4 A to 0.6 A range).
Global Supply Chain: We offer reliable global shipping (DDU default, DDP available) to ensure timely delivery of custom BDD electrodes for research and commercial projects worldwide.

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

View Original Abstract

The application of combined chemical coagulation and electrochemical oxidation processes to treat a leachate from an intermunicipal sanitary landfill was evaluated.Chemical coagulation (CC) experiments were performed with lime (Ca(OH)2), and the influence of the lime concentration, stirring speed and assay duration were studied.In the electrochemical oxidation (EO) assays, a boron-doped diamond anode was used, and two applied current intensities were tested.It was also evaluated the influence of the lime concentration used in the CC pre-treatment on the EO performance.In the CC assays, the highest COD removals were obtained for lime concentrations of 20 and 25 g L -1 , at 100 rpm stirring speed, during 2 h.In the CC+EO combined treatment the highest removals were obtained at the applied current intensity of 0.6 A, being the influence of the lime concentration used in the pre-treatment almost insignificant.The highest current efficiency was obtained for the combined treatment with EO assays performed at 0.4 A.

Tech Support

Original Source

DOI: https://doi.org/10.4152/pea.201504241