COD Abatement via Segmented BDD and SnO2-Sb2O5 Anodes
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Solution Overview
Problem
Existing electrochemical techniques for pre-treating effluents rich in Chemical Oxygen Demand (COD) upstream of biological purification units face challenges with low faradic yields, particularly with tin and antimony oxide-coated electrodes, and the high cost and brittleness of boron-doped diamond electrodes limit their effectiveness.
Innovation Solution
The simultaneous use of tin and antimony oxide-based anodes and boron-doped diamond electrodes in series or parallel, with adjustable current apportionment, to enhance COD reduction rates and faradic yields, utilizing the more affordable and robust tin and antimony oxide-based anodes in conventional reactors and the BDD electrode for specific reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If boron-doped diamond electrodes are used, then COD reduction rate and faradic yield are improved, but cost and device complexity increase due to brittleness requiring special electrolysers
Solution Approach 1:
The electrolysis system is divided into two separate electrolysers: one containing boron-doped diamond electrodes for initial COD degradation, and another with tin/antimony oxide-coated electrodes for completing oxidation. This segmentation allows each electrolyser to be optimized for its specific function, avoiding the need for complex special electrolysers while maintaining high COD reduction rates and faradic yields
2Loss of energy
If boron-doped diamond electrodes are used, then faradic yield is improved, but cost increases
Solution Approach 1:
The boron-doped diamond electrodes perform only the initial partial oxidation of COD (degrading molecular backbones), while the more economical tin/antimony oxide-coated electrodes complete the oxidation process. This partial action approach maintains high faradic yield (above 24%) while significantly reducing overall cost by limiting BDD electrode usage to the extent necessary for effective pre-treatment
3Ease of manufacture
If tin and antimony oxide-coated electrodes are used, then cost and ease of operation are improved, but faradic yield and COD reduction rate deteriorate
Solution Approach 1:
The boron-doped diamond electrodes perform preliminary action by degrading the molecular backbones of COD-containing compounds first, converting complex organic molecules into smaller, more oxidizable fragments. This preliminary degradation enables the subsequent tin/antimony oxide-coated electrodes to achieve much higher COD reduction rates and faradic yields than they could alone
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly improves COD destruction rates with better faradic yields and lower electric energy costs, while minimizing the use of expensive BDD electrodes, achieving up to 80% COD destruction in 100 hours with improved efficiency.
Implementation Method 1
COD oxidation may be carried out by electrolysis on anodes characterised by high oxygen evolution overvoltage or with similar specific electrocatalytic properties
Implementation Method 2
COD oxidation may be carried out by electrolysis on anodes characterised by high oxygen evolution overvoltage
Implementation Method 3
anodes characterised by high oxygen evolution overvoltage
Data Source
AI summary
The invention relates to an effluent COD treatment procedure by anodic oxidation combining the use of two different types of anode with a suitable apportionment of current. The first type of anode comprises an anode based on diamond doped-synthetic diamond. The second type of anode comprises an anode with high oxygen overvoltage containing tin and antimony oxides.