Emerging Contaminants Decontamination of WWTP Effluents by BDD Anodic Oxidation - A Way towards Its Regeneration

At a Glance

Metadata	Details
Publication Date	2023-04-25
Journal	Water
Authors	Joaquín R. Domínguez, T. González, Sergio E. Correia, Maria M. Núñez
Institutions	Universidad de Extremadura
Citations	9
Analysis	Full AI Review Included

Technical Documentation & Analysis: BDD Anodic Oxidation for Water Regeneration

Reference Paper: Dominguez et al. (2023). Emerging Contaminants Decontamination of WWTP Effluents by BDD Anodic Oxidation: A Way towards Its Regeneration. Water, 15, 1668.

Executive Summary

6CCVD analyzes this research demonstrating the critical role of Boron-Doped Diamond (BDD) anodes in achieving high-efficiency water regeneration from complex wastewater matrices.

High Removal Efficiency: Electrochemical Oxidation (EO) using BDD anodes achieved 100% removal of a broad group of emerging contaminants (ECs), including neonicotinoid pesticides, azole pesticides, antibiotics, and antidepressants, in real WWTP effluent.
Superior Mineralization: BDD proved highly effective at mineralization, achieving Total Organic Carbon (TOC) removal up to 77.09%, confirming the superior oxidizing power of BDD-generated hydroxyl radicals ($\cdot$OH).
Kinetic Performance: The degradation process followed pseudo-first-order kinetics, with reactivity ranking: Antidepressants > Antibiotics > Azole Pesticides > Neonicotinoids.
Energy Optimization: Specific Energy Consumption (SEC) was successfully minimized, showing a potential cost reduction of up to 38% by optimizing electrolyte conductivity.
Material Validation: The study validates BDD as the optimal anode material for Advanced Oxidation Processes (AOPs) targeting refractory organic pollutants in complex, real-world aqueous matrices.
Scale-Up Potential: The results confirm the feasibility of BDD EO technology for tertiary treatment and regeneration of WWTP effluents, supporting future pilot and industrial scale implementation.

Technical Specifications

The following hard data points were extracted from the experimental results, focusing on the BDD electrode performance and process efficiency.

Parameter	Value	Unit	Context
Anode Material	Boron-Doped Diamond (BDD)	N/A	Source of highly reactive $\cdot$OH radicals
Cathode Material	Stainless Steel (AISI 304)	N/A	Counter electrode used in the cell
Electrode Geometric Area	78	cm²	Circular single-cell reactor size
Electrode Gap	9	mm	Distance between anode and cathode
Current Density ($j$) Range Tested	5.6 to 34.14	mA·cm^-2	Key variable influencing $\cdot$OH generation
Media Conductivity ($C$) Range Tested	1.4 to 5.6	mS·cm^-1	Adjusted using Na₂SO₄
Maximum Pollutant Removal	100	%	Achieved for most ECs (e.g., TMX, ICP, TBZ) at 120 min
Maximum TOC Removal	77.09	%	Achieved at highest current density (34.14 mA·cm^-2)
SEC Range (Specific Energy Consumption)	4.60·10^-3 to 1.44·10^-2	kW·h·g^-1	Energy cost evaluation in WWTP effluent
Energy Cost Reduction Potential	Up to 38	%	Achieved by increasing electrolyte conductivity
Optimal Electrolyte Type	Na₂SO₄	N/A	Provided best degradation results

Key Methodologies

The electrochemical oxidation process utilized BDD anodes in a controlled reactor setup to maximize the generation of oxidizing species.

Reactor Setup: Experiments were conducted in a circular single-cell reactor using a BDD anode and an AISI 304 stainless steel cathode, separated by a 9 mm gap.
Electrode Preparation: BDD electrodes were pre-treated by polarization and cleaning in a 10 mM Na₂SO₄ solution at a current density of 20 mA·cm^-2 for 15 minutes to ensure optimal surface activity.
Matrix Preparation: Real WWTP effluent (Badajoz) was filtered (0.45 µm) and spiked (doped) with mixtures of emerging contaminants (ECs) at a concentration of 1 µM each.
Parameter Variation: The influence of key operational variables—current density ($j$) and media conductivity ($C$)—was systematically evaluated using a Central Composite Design (CCD) and Response Surface Methodology (RSM).
Electrolyte Study: Three supporting electrolytes (Na₂SO₄, NaCl, and NaNO₃) were tested to determine the optimal medium for maximizing pollutant degradation and minimizing energy consumption.
Performance Metrics: Target variables measured included pollutant removal percentage ($E_i$), pseudo-first-order kinetic rate constant ($k_1$), Total Organic Carbon (TOC) removal, and Specific Energy Consumption (SEC).

6CCVD Solutions & Capabilities

This research confirms the superior performance of BDD anodes in complex water treatment applications. 6CCVD is uniquely positioned to supply the high-quality, custom BDD materials required to replicate, optimize, and scale this technology.

Applicable Materials

The high mineralization capacity and radical generation demonstrated are direct results of the BDD anode material.

Boron-Doped Diamond (BDD) Wafers and Plates: 6CCVD specializes in MPCVD BDD, offering precise control over boron doping levels and crystal quality. We supply BDD optimized for electrochemical applications, ensuring maximum $\cdot$OH radical yield and long electrode lifespan necessary for industrial wastewater treatment.
Substrate Options: We offer BDD films deposited on various substrates (e.g., Si, Nb, Ta) up to 10mm thick, providing robust, conductive platforms suitable for high-current density operation in flow reactors.

Customization Potential

The experimental setup used specific circular dimensions (78 cm²). 6CCVD supports the transition from lab-scale testing to pilot-scale implementation through extensive customization capabilities:

Custom Dimensions and Shapes: 6CCVD provides BDD plates and wafers in custom dimensions up to 125mm (PCD) and offers precision laser cutting services to match exact reactor geometries (e.g., circular, rectangular, or complex flow-cell designs).
Thickness Control: We offer SCD and PCD layers with thickness control from 0.1 µm up to 500 µm, allowing engineers to tailor the material for specific current density requirements and cost targets.
Advanced Metalization: While the paper used external connections, scaling up requires robust contacts. 6CCVD offers in-house metalization services (Au, Pt, Pd, Ti, W, Cu) for creating low-resistance electrical contacts, essential for minimizing cell potential ($E_{cell}$) and reducing SEC.
Surface Finish: For applications requiring specific flow dynamics or reduced bubble nucleation, 6CCVD offers high-quality polishing, achieving roughness values of Ra < 5 nm for inch-size PCD.

Engineering Support

The optimization of BDD EO for Emerging Contaminants (ECs) removal requires deep material science expertise, particularly concerning doping levels and surface chemistry.

Application Expertise: 6CCVD’s in-house PhD team provides expert consultation to assist engineers and scientists in selecting the optimal BDD material specifications (doping concentration, thickness, and substrate) required to maximize kinetic rate constants ($k_1$) and minimize Specific Energy Consumption (SEC) for similar Electrochemical Advanced Oxidation Process (AOP) projects.
Global Logistics: We ensure reliable, global shipping (DDU default, DDP available) of sensitive diamond materials, supporting research continuity worldwide.

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

View Original Abstract

Electrochemical oxidation using a boron-doped diamond anode (EO-BDD) was tested to remove emerging contaminants commonly present in wastewater treatment plant effluents (WWTPe). The main objective of the work was the regeneration of this water for its possible reuse in high-quality demanding uses. In the first part of the work, we investigated the potential of this technique for removing a group of neonicotinoid pesticides (thiamethoxam (TMX), imidacloprid (ICP), acetamiprid (ACP), and thiacloprid (TCP)) in a WWTP effluent. The influence of operating variables, such as current density, the conductivity of media, supporting electrolyte type (Na2SO4, NaCl or NaNO3), or the natural aqueous matrix on target variables were fully established. Selected target variables were: (1) the percentage of pollutant removal, (2) the kinetics (apparent pseudo-first-order kinetic rate constant), (3) total organic carbon (TOC) removal, and (4) the specific energy consumption (SEC). A response surface methodology (RSM) was applied to model the results for all cases. In the paper’s final part, this technology was tested with a more broad group of common emerging pollutants, including some azole pesticides (such as fluconazole (FLZ), imazalil (IMZ), tebuconazole (TBZ), or penconazole (PNZ)), antibiotics (amoxicillin (AMX), trimethoprim (TMP), and sulfamethoxazole (SMX)), and an antidepressant (desvenlafaxine (DVF)). The results confirm the power of this technology to remove this emerging contamination in WWTP effluents which supposes an interesting way towards its regeneration.

Tech Support

Original Source

DOI: https://doi.org/10.3390/w15091668

References

2021 - Year-round pesticide contamination of public sites near intensively managed agricultural areas in South Tyrol [Crossref]
2011 - Overview of the status and global strategy for neonicotinoids [Crossref]
2019 - Neonicotinoid poisoning and management [Crossref]
2015 - Environmental fate and exposure; neonicotinoids and fipronil [Crossref]
2015 - Ecological and Landscape Drivers of Neonicotinoid Insecticide Detections and Concentrations in Canada’s Prairie Wetlands [Crossref]
2016 - Field-scale examination of neonicotinoid insecticide persistence in soil as a result of seed treatment use in commercial maize (corn) fields in southwestern Ontario [Crossref]
2016 - Degradation of Thiamethoxam in aqueous solution by ozonation: Influencing factors, intermediates, degradation mechanism and toxicity assessment [Crossref]
2018 - Degradation of acetamiprid in UV/H2O2 and UV/persulfate systems: A comparative study [Crossref]
2019 - Degradation of neonicotinoids by UV irradiation: Kinetics and effect of real water constituents [Crossref]