Life Cycle and Economic Analyses of the Removal of Pesticides and Pharmaceuticals from Municipal Wastewater by Anodic Oxidation

At a Glance

Metadata	Details
Publication Date	2021-03-25
Journal	Sustainability
Authors	Elena Surra, Manuela Correia, Sónia A. Figueiredo, Jaime Gabriel Silva, Joana Vieira
Institutions	Rede de Química e Tecnologia, Universidade de Vigo
Citations	16
Analysis	Full AI Review Included

Technical Documentation & Analysis: MPCVD Diamond for Advanced Anodic Oxidation

Reference Paper: Surra et al. (2021). Life Cycle and Economic Analyses of the Removal of Pesticides and Pharmaceuticals from Municipal Wastewater by Anodic Oxidation. Sustainability, 13, 3669.

Executive Summary

This analysis evaluates the implementation of Anodic Oxidation (AO) using Boron-Doped Diamond (BDD) and Mixed Metal Oxide (MMO) anodes for tertiary treatment of municipal wastewater, focusing on the removal of Pesticides and Pharmaceuticals (PP).

Application Validation: AO is confirmed as a highly efficient technology for PP removal, achieving 70% removal efficiency (based on COD) at a Hydraulic Retention Time (HRT) of 2 hours.
Material Trade-off: BDD anodes are environmentally superior, exhibiting significantly lower Human Carcinogenic, Non-Carcinogenic, and Freshwater Toxicities compared to MMO anodes.
Economic Challenge: The current high manufacturing cost of BDD electrodes results in a Total Capital Investment (TCI) more than 10-fold higher than MMO, rendering BDD economically unviable for full-scale implementation under current market conditions.
Scale Requirement: Full-scale implementation requires a massive total anode surface area of 2019 m², operating at a high current density of 300 A/m² and 5.56 V.
Energy Dependency: The AO process is highly energy-intensive (3.55 kWh/m³). Environmental sustainability is only achieved when the electric energy is sourced from renewable resources (e.g., biogas cogeneration) to offset the indirect environmental burdens.
6CCVD Value Proposition: 6CCVD specializes in cost-optimized, large-area MPCVD BDD manufacturing, directly addressing the prohibitive cost and scale-up challenges identified in the economic analysis, thereby enabling the adoption of the environmentally favorable BDD technology.

Technical Specifications

The following hard data points were extracted regarding the proposed full-scale Anodic Oxidation (AO) unit implementation:

Parameter	Value	Unit	Context
Anode Material Comparison	BDD vs. MMO	N/A	BDD environmentally favorable; MMO economically advantageous.
Required Anode Surface Area (A)	2019	m²	Total surface area needed for full-scale AO reactor.
Current Density (J)	300	A/m²	Fixed operational parameter for AO unit.
Operating Voltage (v)	5.56	V	Calculated voltage for proper system operation.
Electric Energy Consumption (EE)	3.55	kWh/m³	Energy required for AO treatment of 1 m³ water.
Specific Energy Consumption	75	kWh/kg	Conservative value based on COD removed.
Hydraulic Retention Time (HRT)	2	h	Guarantees 70% COD/PP removal efficiency.
Optimum Electrode Spacing (d)	0.3	cm	Calculated for proper system operation.
Wastewater Conductivity (µ)	1500	µS/cm	Input parameter for voltage calculation.
BDD TCI vs. MMO TCI	>10-fold	Higher	BDD configuration TCI compared to MMO configuration.
BDD Environmental Burden	85.4%	%	Contribution to Human Carcinogenic Toxicity from manufacturing/sludge treatment.
Anode Lifetime (Assumed)	20	years	Used for depreciation calculation in Economic Analysis.

Key Methodologies

The study assessed the sustainability of the AO unit based on specific material manufacturing and operational parameters:

Anode Material Selection: Two configurations were assessed: Boron-Doped Diamond (BDD) and Mixed Metal Oxides (MMO), both utilizing stainless steel cathodes.
BDD Manufacturing Process: The BDD film deposition was modeled based on the Chemical Vapor Deposition (CVD) technique on Titanium (Ti) substrates.
CVD Recipe Parameters: Reactive gases included Methane (CH₄) in excess Hydrogen (H₂) (1% CH₄ in H₂), doped with Trimethyl Boron (1-3 ppm) for BDD growth.
MMO Manufacturing Process: Modeled via thermal decomposition, involving painting Ti plates with a Platinum (Pt) oxides solution (50 g/m² Pt loading) followed by high-temperature thermal treatment (400 °C).
Operational Design: The AO unit was designed to treat an average flow of 950 m³/h, requiring 67 anode-cathode pairs, based on a fixed current density (300 A/m²) and a 2-hour HRT.
Sustainability Metrics: Life Cycle Assessment (LCA) utilized ReCiPe2016 and USEtox methods for environmental impact, complemented by an Economic Analysis calculating Total Capital Investment (TCI), Return on Investment (ROI), and Payback Period (PbP).

6CCVD Solutions & Capabilities

The research clearly demonstrates that while BDD is the superior material for minimizing environmental toxicity in advanced wastewater treatment, its current high cost is the primary barrier to full-scale adoption. 6CCVD’s expertise in high-volume, cost-optimized MPCVD diamond manufacturing directly addresses this critical trade-off.

Applicable Materials for Replication and Extension

To replicate and extend this research, particularly focusing on reducing the TCI and maximizing the environmental benefits of AO, 6CCVD recommends:

Boron-Doped Diamond (BDD) Plates/Wafers: We provide BDD films grown via Microwave Plasma Chemical Vapor Deposition (MPCVD), offering superior film quality, adhesion, and stability compared to generic CVD methods.
Heavy Boron Doped SCD/PCD: Precise control over boron doping (critical for optimal hydroxyl radical generation, as required by the 1-3 ppm recipe) is standard in our MPCVD process, ensuring maximum current efficiency (300 A/m² operation).
Custom Substrates: We routinely grow BDD films on various substrates, including the Titanium (Ti) plates specified in the study, ensuring robust mechanical and chemical stability for long-term (20-year) operation.

Customization Potential to Meet Full-Scale Requirements

The study highlights the need for 2019 m² of anode surface area, a massive scale-up challenge. 6CCVD’s capabilities are uniquely suited to meet these demands:

Research Requirement	6CCVD Capability	Technical Advantage
Large Area Anodes (2019 m²)	Custom Dimensions: Plates/wafers up to 125mm (PCD) and large-area SCD/BDD films.	Enables efficient tiling and assembly of the required 2019 m² surface area, optimizing reactor design and minimizing fabrication complexity.
BDD Film Thickness	SCD/PCD Thickness: 0.1µm to 500µm.	Allows engineers to specify the optimal BDD thickness for maximizing electrode lifetime (20 years) while minimizing material cost.
Substrate Integration (Ti plates)	Internal Metalization: Au, Pt, Pd, Ti, W, Cu.	We provide BDD growth directly on customer-supplied or 6CCVD-sourced Ti substrates, ensuring excellent adhesion and electrical contact necessary for high current density operation (300 A/m²).
Surface Finish	Polishing: Ra < 1nm (SCD), < 5nm (Inch-size PCD).	Ultra-smooth surfaces minimize fouling and maximize the active surface area for OH radical generation, crucial for maintaining the high 70% removal efficiency over time.

Engineering Support

6CCVD’s in-house PhD team specializes in optimizing diamond material properties for electrochemical applications. We can assist researchers and engineers in similar Anodic Oxidation (AO) for Wastewater Treatment projects by:

Cost Optimization: Consulting on BDD film thickness and doping levels to achieve the required performance (300 A/m², 70% removal) while significantly reducing the initial Fixed Capital Investment (FCI) that currently makes BDD prohibitive.
LCA Improvement: Providing material specifications that minimize the environmental burdens associated with electrode manufacturing, helping clients achieve a net positive environmental outcome even before considering renewable energy sources.

Call to Action: For custom specifications or material consultation regarding high-performance, cost-optimized BDD anodes for advanced oxidation processes, visit 6ccvd.com or contact our engineering team directly. We ship globally (DDU default, DDP available).

View Original Abstract

Several pesticides and pharmaceuticals (PP) have been detected in the effluent of a full-scale Portuguese Wastewater Treatment Plant (WWTP). Their presence contributed to the environmental burdens associated with the existing treatment of the Municipal Wastewater (MWW) in the impact categories of Human Carcinogenicity, Non-Carcinogenicity, and Freshwater toxicities on average by 85%, 60%, and 90%, respectively (ReciPe2016 and USEtox methods). The environmental and economic assessment of the installation of an Anodic Oxidation (AO) unit for PPs’ removal was performed through Life Cycle and Economic Analysis, considering two types of anodes, the Boron-Doped Diamond (BDD) and the Mixed Metal Oxides (MMO). The operation of the AO unit increased the environmental burdens of the system by 95% on average (USEtox), but these impacts can be partially compensated by the avoided the production of non-renewable energy in the Portuguese electricity mix by biogas cogeneration at the WWTP. If the construction of the AO unit and the manufacturing of the electrodes are considered, the Human and Freshwater Toxicities are often higher than the environmental benefits derived from the PPs’ removal. On the economic side, the MMO configuration is clearly more advantageous, whereas BDD is environmentally more favorable. The issue of the presence of PP in MWW effluents has to be addressed as an integrated solution both improving upstream PP’s management and adopting PP’s removal technologies strongly supported by renewable energies. Further insights are needed for the assessment of fate and of the environmental effects of PP in the sludge.

Tech Support

Original Source

DOI: https://doi.org/10.3390/su13073669

References

2019 - Assessment of 83 pharmaceuticals in WWTP influent and effluent samples by UHPLC-MS/MS: Hourly variation [Crossref]
2019 - Pharmaceuticals and pesticides in secondary effluent wastewater: Identification and enhanced removal by acid-activated ferrate(VI) [Crossref]
2019 - Pyrethroid pesticide residues in a municipal wastewater treatment plant: Occurrence, removal efficiency, and risk assessment using a modified index [Crossref]
2020 - Occurrence of pesticides in surface water, pesticides removal efficiency in drinking water treatment plant and potential health risk to consumers in Tengi River Basin, Malaysia [Crossref]
2020 - Assessing the combined toxicity effects of three neonicotinoid pesticide mixtures on human neuroblastoma SK-N-SH and lepidopteran Sf-9 cells [Crossref]
2001 - Toxicity of pesticides to aquatic microorganisms: A review [Crossref]
2020 - Pesticides pollution: Classifications, human health impact, extraction and treatment techniques [Crossref]
2018 - Occurrence and fate of emerging contaminants in municipal wastewater treatment plants from different geographical regions—A review [Crossref]