Treatment of cheese whey wastewater by electrochemical oxidation using BDD, Ti/RuO2-TiO2, and Ti/RuO2-IrO2-Pt anodes - ecotoxicological and energetic evaluation

At a Glance

Metadata	Details
Publication Date	2025-03-04
Journal	Environmental Science and Pollution Research
Authors	Imen Souli, Annabel Fernandes, Ana Lopes, Inês B. Gomes, Alexandra Afonso
Institutions	University of Gabès, University of Beira Interior
Citations	3
Analysis	Full AI Review Included

Technical Documentation & Analysis: High-Performance BDD Anodes for Industrial Wastewater Treatment

Executive Summary

This analysis confirms the critical role of Boron-Doped Diamond (BDD) anodes in achieving high-efficiency electrochemical oxidation (EO) for complex industrial effluents, specifically Cheese Whey Wastewater (CWW).

Superior Mineralization: BDD anodes achieved the highest removal rates for Chemical Oxygen Demand (COD, up to 86%), Total Dissolved Carbon (TDC), and Dissolved Organic Carbon (DOC) across all tested current densities (j).
Toxicity Reduction: BDD was uniquely effective in reducing ecotoxicity towards Daphnia magna, lowering Toxic Units (TU) from 21.7 (“very toxic”) to 1.87 (“toxic”), nearly reaching the “non-toxic” threshold.
Mechanism Advantage: The high oxygen overpotential of BDD favors the generation of physisorbed hydroxyl radicals (BDD(•OH)), leading to complete mineralization and avoiding the formation of toxic organochlorine byproducts observed with Ti/MMO anodes in high-chloride media (800 mg L^-1).
Biodegradability Enhancement: BDD treatment significantly increased the biodegradability index (BOD₅/COD ratio) from 0.55 to 0.81, making subsequent biological treatment feasible.
6CCVD Value Proposition: 6CCVD provides the high-quality, custom MPCVD BDD required for these demanding applications, ensuring superior performance, longevity, and environmental compliance compared to traditional metal oxide electrodes.

Technical Specifications

Parameter	Value	Unit	Context
Anode Material (Best Performance)	BDD	-	Highest COD/DOC removal, lowest final toxicity
Max COD Removal (BDD)	86	%	Achieved after 8 h at 500 A m^-2
Initial BOD₅/COD Ratio	0.55	-	Raw CWW (classified as “fairly biodegradable”)
Final BOD₅/COD Ratio (BDD)	0.81	-	Treated CWW (Enhanced biodegradability)
Initial Ecotoxicity (TU)	21.7	Toxic Units	Raw CWW (classified as “very toxic”)
Final Ecotoxicity (TU) (BDD)	1.87	Toxic Units	Treated CWW (Reduced to “toxic,” near “non-toxic”)
Minimum EEO (Ti/MMO)	117	kWh m^-3 order^-1	Ti/RuO₂-IrO₂-Pt at 50 A m^-2 (Energy consumption metric)
Initial Chloride Concentration	800 ± 9	mg L^-1	High chloride content favored toxic byproduct formation on Ti/MMO
Anode Immersed Area	10	cm²	Lab-scale experimental area
Inter-Electrode Gap	0.5	cm	Cell geometry parameter

Key Methodologies

The electrochemical oxidation (EO) assays were conducted in a batch configuration using an undivided cylindrical glass cell.

Anode Materials: Boron-Doped Diamond (BDD), Ti/RuO₂-TiO₂, and Ti/RuO₂-IrO₂-Pt.
Cathode Material: Stainless-steel plate.
Electrode Configuration: Parallel plates, 10 cm² immersed area, 0.5 cm gap.
Operating Mode: Batch, 8 hours duration, constant stirring (200 rpm).
Applied Current Densities (j): Four levels tested:
1. 50 A m^-2
2. 100 A m^-2
3. 300 A m^-2
4. 500 A m^-2
Wastewater Characteristics (Raw CWW): Highly alkaline (pH 11.8 ± 0.1), high organic load (COD 3.9 g L^-1), and high salinity (Chloride 800 mg L^-1).
Evaluation Metrics: COD, DOC, TDN removal, Instantaneous Current Efficiency (ICE), Electric Energy per Order (EEO), BOD₅/COD ratio, and ecotoxicity via Daphnia magna assay.

6CCVD Solutions & Capabilities

The research clearly validates BDD as the superior anode material for achieving high mineralization, biodegradability enhancement, and critical ecotoxicity reduction in complex industrial wastewater treatment. 6CCVD is uniquely positioned to supply the high-performance diamond materials necessary to replicate and scale this success.

Applicable Materials

To replicate or extend this research, the primary material required is high-quality, robust BDD.

Research Requirement	6CCVD Solution	Technical Specification
High Mineralization Anode	Heavy Boron-Doped Diamond (BDD)	MPCVD BDD wafers/plates (0.1 µm to 500 µm thickness). Optimized doping for high O₂ overpotential and BDD(•OH) generation.
Alternative Substrates (MMO comparison)	Polycrystalline Diamond (PCD) Substrates	PCD plates up to 125mm diameter, ideal for use as robust, conductive substrates for novel hybrid coatings (e.g., diamond layer over Ti/MMO).
High Current Density Operation	Thermally Managed SCD/PCD	SCD or PCD substrates up to 10mm thick, providing excellent thermal management crucial for maintaining electrode durability at high current densities (j ≥ 300 A m^-2).

Customization Potential for Scale-Up

The study utilized small, 10 cm² electrodes. Industrial implementation requires large-format, custom-engineered electrodes.

Custom Dimensions: 6CCVD provides custom BDD and PCD plates/wafers up to 125mm in diameter. We can supply electrodes cut to precise specifications (e.g., the 10 cm² area used in the study, or larger prototypes) using our in-house laser cutting capabilities.
Surface Finish: While the paper focused on chemical performance, electrode longevity is tied to surface quality. We offer ultra-smooth polishing (Ra < 1nm for SCD, Ra < 5nm for inch-size PCD) to minimize fouling and maximize service life in high-fouling environments like CWW.
Metalization Services: The study used Ti/RuO₂-IrO₂-Pt anodes. For researchers developing novel hybrid diamond electrodes or requiring robust electrical contacts for high-current operation, 6CCVD offers internal metalization capabilities, including Au, Pt, Pd, Ti, W, and Cu deposition.

Engineering Support

The successful application of EO-BDD technology, particularly in complex matrices like CWW (high pH, high chloride), requires specialized material knowledge.

6CCVD’s in-house PhD team can assist with material selection, doping optimization, and electrode design for similar Electrochemical Wastewater Remediation projects. We ensure that the supplied BDD material meets the stringent requirements for high current efficiency and long-term stability necessary for industrial scale-up.

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

View Original Abstract

Abstract The effectiveness of boron-doped diamond (BDD) and titanium metal-mixed oxides (Ti/MMO: Ti/RuO 2 -TiO 2 and Ti/RuO 2 -IrO 2 -Pt) anodes to treat cheese whey wastewater (CWW) by electrochemical oxidation (EO) was evaluated. The results show that EO with BDD is effective in the removal of organic compounds. Conversely, Ti/MMO anodes exhibit higher removals of nitrogenated compounds. After 8 h of EO treatment at an applied current density of 500 A m −2 , the biodegradability index increased from 0.55 to 0.81 with the BDD anode, while with Ti/MMO only reached 0.64. The acute toxicity of the CWW, before and after treatment, was assessed with the model organism Daphnia magna . The use of BDD showed favorable outcomes, leading to a reduction in ecotoxicity, which changed the CWW classification from “very toxic” to “toxic,” very close to the “non-toxic” level. Contrarywise, the use of Ti/MMO anodes led to an escalation of potentially harmful substances in the treated effluent. Still, Ti/MMO anodes provide the most favorable energy consumption when operating at current densities equal to or below 100 A m −2 . While both Ti/RuO 2 -TiO 2 and Ti/RuO 2 -IrO 2 -Pt exhibit similar performance, the effectiveness of Ti/RuO 2 -TiO 2 is somewhat lower.

Tech Support

Original Source

DOI: https://doi.org/10.1007/s11356-025-36174-0