Reuse of Textile Dyeing Wastewater Treated by Electrooxidation

At a Glance

Metadata	Details
Publication Date	2022-03-29
Journal	Water
Authors	Cláudia Pinto, Annabel Fernandes, Ana Lopes, Maria João Nunes, Ana Baía
Institutions	University of Beira Interior
Citations	17
Analysis	Full AI Review Included

Technical Documentation: BDD Anodes for Advanced Electrochemical Wastewater Reuse

This document analyzes the application of Boron-Doped Diamond (BDD) anodes in the electrochemical oxidation (EO) of textile dyeing wastewater (TDW) for sustainable reuse, based on the research paper “Reuse of Textile Dyeing Wastewater Treated by Electrooxidation.”

Executive Summary

The research validates the use of Boron-Doped Diamond (BDD) anodes for highly effective electrochemical advanced oxidation processes (EAOPs) targeting the reuse of recalcitrant textile dyeing wastewater (TDW).

Material Validation: Confirms BDD’s superior performance in generating highly reactive species (hydroxyl radicals and peroxodisulfate) necessary for non-selective mineralization of complex organic pollutants.
High-Quality Water Achieved: EO treatment at 100 mA cm^-2 successfully produced “High-Quality” reuse water, achieving a Chemical Oxygen Demand (COD) concentration of 45 ± 3 mg L^-1, significantly below the 50 mg L^-1 threshold required for high-quality textile reuse.
Salt Recovery & Savings: The process maintained the sulfate ion concentration (~670 mg L^-1) unchanged, enabling complete salt recovery and eliminating the need for sodium sulfate addition in subsequent dyeing cycles.
Ecotoxicity Mitigation: The BDD EO process drastically reduced ecotoxicity towards the model organism Daphnia magna by up to 18.6-fold, ensuring safe and sustainable consecutive wastewater reuse.
Consecutive Reuse Feasibility: Demonstrated successful consecutive reuse cycles, with the treated TDW yielding dyed fabrics that complied with the most restrictive textile industry controls (Total Color Difference, ΔE*, ≤ 1.0).
Scalability Proof: The findings support the industrial scalability of BDD-based EO systems for zero liquid discharge (ZLD) strategies in the textile finishing sector.

Technical Specifications

The following hard data points were extracted, detailing the BDD electrode configuration and performance metrics for TDW treatment:

Parameter	Value	Unit	Context
Anode Material	Si/BDD (Commercial)	N/A	High O₂-overpotential anode
Immersed Electrode Area	10	cm²	Lab-scale undivided cylindrical cell
Inter-Electrode Gap	1	cm	EO setup configuration
Applied Current Density (j)	60 and 100	mA cm^-2	Operational parameters studied
Treatment Duration	10	hours	Time required for complete discoloration
Initial COD (TDW)	(4.6 ± 0.1) x 10³	mg L^-1	Primary dyeing wastewater
Final COD (Moderate Quality)	163 ± 8	mg L^-1	After 10h EO at 60 mA cm^-2
Final COD (High Quality)	45 ± 3	mg L^-1	After 10h EO at 100 mA cm^-2
Ecotoxicity Reduction Factor	Up to 18.6	-fold	Achieved during second reuse cycle (100 mA cm^-2)
Salt Concentration (SO₄^2-)	~670	mg L^-1	Unchanged after EO, enabling salt recovery
Total Color Difference (ΔE*)	≤ 1.0	N/A	Complies with most restrictive textile controls

Key Methodologies

The electrochemical oxidation (EO) process utilized a BDD anode to treat textile dyeing wastewater (TDW) in a batch reactor setup.

Wastewater Source: TDW generated from dyeing 100% wool twill fabric using a trichromatic combination of Nylosan acid dyes, sulfate salt (sodium sulfate), and organic auxiliary agents (equalizer and humectant).
Pre-Treatment: TDW was filtered through 0.45 µm membrane filters to remove fiber residues prior to EO treatment.
Electrochemical Cell: Undivided cylindrical cell containing 250 mL of TDW, operated in batch mode with stirring (300 rpm).
Electrodes: A commercial Si/BDD anode and a stainless-steel cathode were used, each with an immersed area of 10 cm² and an inter-electrode gap of 1 cm.
Power Supply: A GW, Lab DC, model GPS-3030D (0-30 V, 0-3 A) was used to maintain constant current density.
Operational Parameters: EO treatment was performed for 10 hours at two key current densities ($j$): 60 mA cm^-2 (targeting moderate quality water) and 100 mA cm^-2 (targeting high quality water).
Mechanism Focus: The high oxygen evolution potential of the BDD anode promoted the generation of peroxodisulfate (S₂O₈^2-) and sulfate radicals (SO₄^•-) from the existing sulfate ions, driving non-selective organic mineralization.
Reuse Strategy: Treated TDW was utilized in subsequent dyeing baths without dilution and critically, without the addition of fresh sodium sulfate salt.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to support the replication, optimization, and industrial scaling of this BDD-based electrochemical oxidation technology for wastewater reuse. Our expertise in MPCVD diamond growth ensures the highest quality BDD material required for these demanding EAOP applications.

Applicable Materials

The core success of this research relies on the high overpotential and chemical stability of the BDD anode. 6CCVD offers application-specific diamond materials:

Heavy Boron-Doped Diamond (BDD) Wafers/Plates: Essential for maximizing the generation of reactive oxygen species (ROS) and reactive sulfate species (SO₄^•-) required for high-efficiency COD reduction and mineralization. We provide BDD films with optimized doping concentrations to ensure superior conductivity and long-term stability under high current density operation (up to 100 mA cm^-2 and beyond).
Polycrystalline Diamond (PCD) Substrates: Available for large-area electrode fabrication, offering robust mechanical support for BDD films in industrial reactor environments.

Customization Potential

The research utilized a small, 10 cm² electrode. Scaling this technology requires custom dimensions and integration capabilities, which are 6CCVD specialties:

Research Requirement	6CCVD Customization Service	Industrial Scaling Advantage
Scaling Electrode Area	Custom BDD plates/wafers up to 125mm diameter.	Enables direct scale-up from lab-scale (10 cm²) to pilot or full industrial flow-cell reactors, optimizing throughput and current distribution.
Optimized Geometry	Precision laser cutting and shaping services.	Allows for complex electrode geometries (e.g., rings, meshes, or specific flow-channel inserts) crucial for optimizing mass transfer limitations in high-volume wastewater treatment.
Integration & Contact	Custom Metalization (Ti, Pt, Au, W, Cu) services.	Ensures robust, low-resistance electrical contacts and corrosion protection for BDD films, critical for maintaining performance during long-duration, high-current EO processes.
Film Thickness Control	SCD/PCD/BDD thickness control from 0.1 µm up to 500 µm.	Tailored BDD film thickness balances cost efficiency with required electrochemical lifetime and performance stability.

Engineering Support

6CCVD’s in-house team of PhD material scientists and electrochemical engineers specializes in Advanced Oxidation Processes (AOPs) and material selection for extreme environments.

Electrochemical Recipe Optimization: We assist clients in defining the optimal BDD doping level and substrate choice to maximize the efficiency of sulfate radical generation (SO₄^•-) for specific industrial effluent matrices (e.g., high chloride vs. high sulfate content).
Reactor Design Consultation: Support for integrating BDD electrodes into industrial flow-through or batch reactors, ensuring compliance with strict reuse quality standards (COD < 50 mg L^-1, ΔE* ≤ 1.0).
Lifetime and Stability Analysis: Providing materials engineered for long operational lifetimes, minimizing replacement costs and maximizing return on investment (ROI) for industrial wastewater reuse projects.

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

View Original Abstract

Wastewater reuse has been addressed to promote the sustainable water utilization in textile industry. However, conventional technologies are unable to deliver treated wastewater with the quality required for reuse, mainly due to the presence of dyes and high salinity. In this work, the feasibility of electrooxidation, using a boron-doped diamond anode, to provide treated textile dyeing wastewater (TDW) with the quality required for reuse, and with complete recovery of salts, was evaluated. The influence of the applied current density on the quality of treated TDW and on the consecutive reuse in new dyeing baths was studied. The ecotoxicological evaluation of the process towards Daphnia magna was performed. After 10 h of electrooxidation at 60 and 100 mA cm−2, discolorized treated TDW, with chemical oxygen demand below 200 (moderate-quality) and 50 mg L−1 (high-quality), respectively, was obtained. Salt content was unchanged in both treatment conditions, enabling the consecutive reuse without any salt addition. For the two reuse cycles performed, both treated samples led to dyed fabrics in compliance with the most restrictive controls, showing that an effective consecutive reuse can be achieved with a moderate-quality water. Besides the water reuse and complete salts saving, electrooxidation accomplished an ecotoxicity reduction up to 18.6-fold, allowing TDW reuse without severe ecotoxicity accumulation.

Tech Support

Original Source

DOI: https://doi.org/10.3390/w14071084

References

2014 - The status of water reuse in European textile sector [Crossref]
2019 - Textile dye wastewater characteristics and constituents of synthetic effluents: A critical review [Crossref]
2018 - Chemical and electrochemical advanced oxidation processes as a polishing step for textile wastewater treatment: A study regarding the discharge into the environment and the reuse in the textile industry [Crossref]
2016 - A critical review on textile wastewater treatments: Possible approaches [Crossref]
2020 - Recent advances in the treatment of dye-containing wastewater from textile industries: Overview and perspectives [Crossref]
2021 - A review on the treatment of textile industry effluents through Fenton processes [Crossref]
2018 - Application of a planar falling film reactor for decomposition and mineralization of methylene blue in the aqueous media via ozonation, Fenton, photocatalysis and non-thermal plasma: A comparative study [Crossref]
2017 - Electrochemical advanced oxidation processes: A review on their application to synthetic and real wastewaters [Crossref]